WO2013042514A1 - Fluoroscopy device, method for setting region of interest for fluoroscopy device, radiography system, and fluoroscopy control program - Google Patents

Fluoroscopy device, method for setting region of interest for fluoroscopy device, radiography system, and fluoroscopy control program Download PDF

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Publication number
WO2013042514A1
WO2013042514A1 PCT/JP2012/071895 JP2012071895W WO2013042514A1 WO 2013042514 A1 WO2013042514 A1 WO 2013042514A1 JP 2012071895 W JP2012071895 W JP 2012071895W WO 2013042514 A1 WO2013042514 A1 WO 2013042514A1
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Prior art keywords
radiation
exposure
region
moving image
interest
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PCT/JP2012/071895
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French (fr)
Japanese (ja)
Inventor
西納　直行
北野　浩一
岩切　直人
大田　恭義
中津川　晴康
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富士フイルム株式会社
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Publication of WO2013042514A1 publication Critical patent/WO2013042514A1/en

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/46—Arrangements for interfacing with the operator or the patient
    • A61B6/467—Arrangements for interfacing with the operator or the patient characterised by special input means
    • A61B6/469—Arrangements for interfacing with the operator or the patient characterised by special input means for selecting a region of interest [ROI]
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/48—Diagnostic techniques
    • A61B6/486—Diagnostic techniques involving generating temporal series of image data
    • A61B6/487—Diagnostic techniques involving generating temporal series of image data involving fluoroscopy
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/54—Control of apparatus or devices for radiation diagnosis
    • A61B6/542—Control of apparatus or devices for radiation diagnosis involving control of exposure
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/44—Constructional features of apparatus for radiation diagnosis
    • A61B6/4429—Constructional features of apparatus for radiation diagnosis related to the mounting of source units and detector units
    • A61B6/4464—Constructional features of apparatus for radiation diagnosis related to the mounting of source units and detector units the source unit or the detector unit being mounted to ceiling

Definitions

  • the present invention generates a moving image of a subject by continuously radiating radiation toward the subject and continuously capturing still images obtained by receiving a radiation amount passing through the subject with a radiation detector.
  • the present invention relates to a radiation moving image capturing apparatus, a region of interest setting method for a radiation moving image capturing apparatus, a radiation image capturing system, and a radiation moving image capturing control program.
  • radiation detectors such as FPD (Flat Panel Detector) that can arrange radiation sensitive layers on TFT (Thin Film Transistor) active matrix substrates and convert radiation dose into digital data (electrical signals) (referred to as “electronic cassettes”)
  • FPD Fluor Deposition Detector
  • TFT Thin Film Transistor
  • electrospray cassettes a radiation image capturing apparatus that captures a radiation image represented by the amount of radiation that has been exposed using this radiation detector has been put into practical use.
  • the radiation dose is, for example, interchangeably converted into a light emission amount and then converted into an electric signal, and then a direct conversion method in which the radiation dose is directly converted into an electric signal, and is selected as appropriate. Adopted.
  • the radiographic imaging apparatus As described above, it is considered to display a so-called moving image by continuously reproducing image information detected by a radiation detector at regular intervals. Note that the shorter the time interval, the better the continuity and the better the image quality as a moving image. However, the amount of image information is increased by using a general CCD or CMOS. It is the same as an imaging device (image sensor). In the radiographic image capturing apparatus, if the number of image frames to be captured increases, the radiation dose to the subject increases. Therefore, it is preferable to select an appropriate number of image frames.
  • the “appropriate number of image frames” refers to whether the movement of the imaging target (image in the region of interest (ROI) in the subject) is fast or slow, whether or not the change amount of the movement is important, etc. This is the number of image frames decided according to the purpose.
  • Japanese Patent Laid-Open No. 2010-273434 discloses an X-ray diagnostic imaging apparatus that displays a fluoroscopic image of a contrasted blood vessel and a DA (Digital Angiography) image.
  • Japanese Patent Laid-Open No. 9-266901 discloses an image processing condition setting device for radiographic images.
  • Japanese Patent Application Laid-Open No. 2010-27383 discloses an X-ray diagnostic imaging apparatus that performs ABC control based on an image level in a region of interest by appropriately canceling ABC control according to a user operation, and the X-ray condition at that time A technique that can fix the above is disclosed.
  • the radiation dose emitted from the radiation generating device may be reduced.
  • the ABC control is executed before the region of interest is determined.
  • the radiation dose may be controlled to increase in spite of the so-called pre-photographing image.
  • Patent Document 1 cancels ABC control according to a user operation, and there is no causal relationship between ABC control and a region of interest.
  • Japanese Patent Laid-Open No. 2009-101208 does not perform ABC control, but performs normal shooting at the time of the first exposure for setting a region of interest. After setting the region of interest, a technique for controlling the collimator so that only the region of interest is exposed to radiation is disclosed.
  • the present invention mainly provides a moving image radiographing apparatus and a radiographic moving image capable of reducing the radiation exposure dose to a subject without adversely affecting the identification of a region of interest when capturing a moving image. It is an object to obtain a region-of-interest setting method for an image capturing apparatus, a radiation image capturing system, and a radiation moving image capturing control program.
  • a plurality of pixels are used to determine the amount of radiation that has been emitted from radiation exposure means that exposes radiation of radiation energy in a set steady range toward a subject and has passed through the subject.
  • a radiation image capturing unit that receives a radiation signal in accordance with the amount of radiation received for each pixel received by the radiation detector provided, and obtains the gradation signal from the radiation image capturing unit, and has a predetermined dynamic range.
  • Reading the gradation signal Reading the gradation signal, generating still image information for each frame, and moving image information generating means for generating a moving image of the subject by continuously capturing the still images;
  • Control means for feedback controlling the set value of the radiation energy of the radiation to be emitted from the radiation exposure means at a predetermined control cycle, instructing prohibition of feedback control by the control means, and instructing the radiation exposure means Then, pre-exposure for a still image is performed, and a gradation signal corresponding to a still image for at least one frame based on the pre-exposure is acquired from the radiation image capturing unit, and generated from the gradation signal.
  • a region of interest setting means for setting a partial region of the still image as a region of interest.
  • the radiation amount irradiated from the radiation exposure means and passed through the subject is received by a radiation detector having a plurality of pixels, and a gradation signal corresponding to the radiation amount received for each pixel Is output.
  • the moving image information generating means acquires the gradation signal from the radiation image photographing means, reads the gradation signal under a predetermined steady dynamic range, and generates still image information for each frame. Then, a moving image of the subject is generated by continuously capturing still images.
  • control means feedback-controls the set value of the radiation energy of the radiation exposed from the radiation exposure means at a predetermined control cycle.
  • the region of interest setting means sets the region of interest from the moving images to be photographed.
  • the region-of-interest setting unit prohibits feedback control by the control unit and captures a still image by pre-exposure prior to moving image capturing. Based on this still image, a part of the image is set as a region of interest.
  • the subject is exposed only during still image shooting, and the exposure dose of the subject is suppressed from the normal range. can do. Moreover, the state which was suppressed can be maintained by prohibiting feedback control.
  • the prohibition of feedback control by the control means is canceled and the generation of the moving image is started.
  • the exposure dose due to still image shooting during the pre-exposure by the radiation exposure means is suppressed to be less than the exposure dose during generation of a still image for one frame during shooting of the moving image.
  • the still image by pre-exposure is applied only to setting the region of interest, for example, an image having high image quality (high-quality still image) enough to accurately observe the affected area of the subject is unnecessary.
  • the amount of exposure can be suppressed by the difference in application purpose.
  • the suppression of the exposure dose is to make the radiation energy instructed to the radiation exposure means lower than a steady range.
  • the exposure dose to the subject can be reduced by making the radiation energy of the radiation source itself lower than the steady range.
  • the rate of change of the image information with respect to the gradation signal which is a parameter of compression of the dynamic range is being feedback controlled. Adjust to make it larger.
  • the radiation energy instructed to the radiation exposure means is set lower than the steady range, the radiation amount itself detected for each pixel decreases, and a gradation signal may not be obtained properly.
  • the dynamic range compression parameter is made larger than the dynamic range compression parameter during feedback control.
  • the dynamic range compression parameter is the rate of change of the image information with respect to the gradation signal.
  • the radiation dose received by the radiation detector is small because the radiation energy is low, and the gradation signal tends to be biased toward the low level. Tonal change (density change) is low.
  • Appropriate image information can be obtained from a so-called underimage by increasing the dynamic range compression parameter, that is, the rate of change of the image information with respect to the gradation signal, in accordance with this biased region.
  • the range of the still image applied when the region of interest is set by the region of interest setting means is wider than the range of the moving image captured after the region of interest is set.
  • the range of the still image that is the target of the region of interest is made wider than the range of moving images that are captured after the region of interest is set. As a result, it is possible to prevent the region of interest from being overlooked or misidentified.
  • the target of feedback control by the control means is an image in the region of interest set by the region of interest setting means.
  • the radiation dose can be adjusted separately inside and outside the region of interest, feedback correction is performed so that appropriate radiation energy is obtained within the region of interest, and the radiation dose is reduced outside the region of interest, thereby exposing the subject.
  • the amount of radiation emitted can be reduced.
  • the exposure surface of the radiation exposure means is partitioned and controlled independently, or between the radiation exposure means and the subject.
  • means such as arranging an aperture can be considered, and in the case of a moving image, the movement of the region of interest may be followed.
  • pre-exposure for a still image is performed toward a subject prior to moving image capturing by continuous exposure of radiation energy, and based on radiation energy passing through the subject by the pre-exposure.
  • the second aspect of the invention for example, as a normal moving image capturing procedure, radiation of radiation energy in a set steady range is exposed toward the subject and the amount of radiation that has passed through the subject. A corresponding gradation signal is read under a predetermined dynamic range to generate still image information for each frame, and a moving image of the subject is generated by continuously capturing still images.
  • the set value of the radiation energy of the radiation to be exposed is feedback-controlled at a predetermined control cycle.
  • the region of interest is set from the moving images to be shot.
  • feedback control is prohibited and a part of the image is set as the region of interest while the exposure dose of the subject is suppressed from the steady range.
  • the subject is exposed only during still image shooting, and the exposure dose of the subject is suppressed from the normal range. can do. Moreover, the state which was suppressed can be maintained by prohibiting feedback control.
  • the radiation energy of the radiation at the time of the pre-exposure is set lower than that at the time of moving image shooting.
  • the radiation dose to the subject can be reduced by making the radiation energy of the radiation source itself lower than the steady range.
  • the compression ratio of the dynamic range is adjusted so that the change amount of the gradation signal with respect to the radiation energy is increased by the amount that the radiation energy is set low.
  • the amount of radiation detected for each pixel decreases, and a gradation signal may not be obtained properly.
  • the dynamic range compression parameter is made larger than the dynamic range compression parameter during feedback control.
  • the dynamic range compression parameter is the rate of change of the image information with respect to the gradation signal.
  • the radiation dose received by the radiation detector is small because the radiation energy is low, and the gradation signal tends to be biased toward the low level. Tonal change (density change) is low.
  • Appropriate image information can be obtained from a so-called underimage by increasing the dynamic range compression parameter, that is, the rate of change of the image information with respect to the gradation signal, in accordance with this biased region.
  • the radiological moving image capturing apparatus according to any one of the first to sixth aspects of the present invention, a terminal apparatus that inputs and browses diagnostic information and facility reservations, and requests radiographic image capturing and reservations.
  • a radiographic imaging system comprising: a server that accepts an imaging request from the terminal device, manages a radiographic imaging schedule in the radiographic video imaging device, and collectively manages radiographic images taken.
  • the third aspect of the invention can be applied as a system for managing information such as medical appointment reservations and diagnostic records, particularly in a radiology department in a hospital, and can be a part of a hospital information system.
  • the radiation energy suppression rate at the time of setting the region of interest is determined for each subject. Can be adjusted.
  • a fourth aspect of the present invention is a radiation moving image photographing control that causes a computer to function as moving image information generating means, control means, and region of interest setting means of any one of the first to sixth inventions. It is a program. Note that the radiation moving image capturing control program can be stored in a storage medium.
  • the present invention has an excellent effect that the radiation exposure dose to the subject can be reduced without adversely affecting the identification of the region of interest.
  • FIG. 10 (2) is in FIG. 11 (1). It is a histogram of the QL value when the dynamic range is compressed.
  • FIG. 6 is a characteristic diagram showing a radiation moving image photographing process-radiation exposure dose cumulative value characteristic curve. It is the block diagram which showed the flow of imaging
  • FIG. 1 is a schematic configuration diagram of a radiation information system (hereinafter referred to as “RIS” (Radiology Information System)) 10 according to the present embodiment.
  • the RIS 10 can capture a moving image in addition to a still image.
  • the definition of a moving image means that still images are displayed one after another at a high speed and recognized as a moving image.
  • the still image is photographed, converted into an electric signal, transmitted, and the still image is converted from the electric signal.
  • the process of replaying is repeated at high speed. Accordingly, the so-called “frame advance” in which the same area (part or all) is photographed a plurality of times within a predetermined time and continuously reproduced in accordance with the degree of the “high speed” is also included in the moving image.
  • frame advance in which the same area (part or all) is photographed a plurality of times within a predetermined time and continuously reproduced in accordance with the degree of the “high speed” is also included in the moving image.
  • the RIS 10 is a system for managing information such as medical appointments and diagnosis records in the radiology department, and constitutes a part of a hospital information system (hereinafter referred to as “HIS” (Hospital Information System)).
  • HIS Hospital Information System
  • the RIS 10 includes a plurality of radiographic imaging systems installed individually in a plurality of imaging request terminal devices (hereinafter referred to as “terminal devices”) 12, a RIS server 14, and a radiographic room (or operating room) in a hospital.
  • terminal devices hereinafter referred to as “terminal devices”
  • RIS server a radiographic room (or operating room) in a hospital.
  • imaging system which are connected to an in-hospital network 18 composed of a wired or wireless LAN (Local Area Network) or the like.
  • the hospital network 18 is connected to an HIS server (not shown) that manages the entire HIS.
  • the radiographic image capturing system 16 may be a single unit or three or more facilities. In FIG. 1, the radiographic image capturing system 16 is installed for each radiographing room. An imaging system 16 may be arranged.
  • the terminal device 12 is used by doctors and radiographers to input and view diagnostic information and facility reservations, and radiographic image capturing requests and imaging reservations are performed via the terminal device 12.
  • Each terminal device 12 includes a personal computer having a display device, and is capable of mutual communication via the RIS server 14 and the hospital network 18.
  • the RIS server 14 receives an imaging request from each terminal device 12 and manages a radiographic imaging schedule in the imaging system 16, and includes a database 14A.
  • the database 14A includes attribute information (name, sex, date of birth, age, blood type, weight, patient ID (Identification), etc.), medical history, Medical history, information about the patient such as radiation images taken in the past, identification number (ID information) of the electronic cassette 20 (model information) used in the imaging system 16, model, size, sensitivity, start date of use, number of uses, etc.
  • ID information information about the electronic cassette 20 and environmental information indicating an environment in which a radiographic image is taken using the electronic cassette 20, that is, an environment in which the electronic cassette 20 is used (for example, a radiographic room or an operating room).
  • medical-related data managed by medical institutions is stored almost permanently, and when necessary, a system (sometimes referred to as a “medical cloud”) that instantly retrieves data from the required location can be used outside the hospital. You may make it acquire the past personal information etc. of a patient (subject) from a server.
  • a system sometimes referred to as a “medical cloud”
  • the imaging system 16 captures a radiographic image by an operation of a doctor or a radiographer according to an instruction from the RIS server 14.
  • the imaging system 16 exposes the subject to the radiation X having a dose according to the exposure conditions from the radiation exposure source 22A that exposes the radiation X under the control of the radiation exposure control unit 22 (see FIG. 4).
  • a radiation generating device 24 that emits radiation
  • a radiation detector 26 that generates radiation by absorbing the radiation X transmitted through the imaging target region of the subject and generates image information indicating a radiation image based on the amount of the generated charge ( 3), a cradle 28 for charging a battery built in the electronic cassette 20, and a console 30 for controlling the electronic cassette 20 and the radiation generator 24.
  • the console 30 acquires various types of information included in the database 14A from the RIS server 14 and stores them in an HDD 88 (see FIG. 4) described later. If necessary, the console 30 uses the information to store the electronic cassette 20 and the radiation generator 24. Take control.
  • FIG. 2 shows an example of the arrangement state of each device in the radiation imaging room 32 of the imaging system 16 according to the present embodiment.
  • the radiation imaging room 32 there are a standing table 34 used when performing radiography in a standing position and a prone table 36 used when performing radiation imaging in a lying position.
  • the space in front of the standing table 34 is set as the imaging position of the subject 38 when performing radiography in the standing position, and the upper space of the prone table 36 is used in performing radiography in the prone position. This is the imaging position of the subject 40.
  • the standing table 34 is provided with a holding unit 42 that holds the electronic cassette 20, and the electronic cassette 20 is held by the holding unit 42 when a radiographic image is taken in the standing position.
  • a holding unit 44 that holds the electronic cassette 20 is provided in the lying position table 36, and the electronic cassette 20 is held by the holding unit 44 when a radiographic image is taken in the lying position.
  • the radiation exposure source 22A is installed in a horizontal position in order to enable radiography in the standing position and in the prone position by the radiation from the single radiation exposure source 22A.
  • Support movement that can rotate around the axis (in the direction of arrow A in FIG. 2), move in the vertical direction (in the direction of arrow B in FIG. 2), and further move in the horizontal direction (in the direction of arrow C in FIG. 2).
  • a mechanism 46 is provided.
  • the drive source that moves (including rotation) in the directions of arrows A to C in FIG. 2 is built in the support moving mechanism 46, and is not shown here.
  • the cradle 28 is formed with an accommodating portion 28A capable of accommodating the electronic cassette 20.
  • the built-in battery is charged in a state of being accommodated in the accommodating portion 28A of the cradle 28.
  • the electronic cassette 20 is taken out of the cradle 28 by a radiographer or the like, and the photographing posture is established. If it is in the upright position, it is held in the holding part 42 of the standing table 34, and if it is in the upright position, it is held in the holding part 44 of the standing table 36.
  • various kinds of information are transmitted by wireless communication between the radiation generator 24 and the console 30 and between the electronic cassette 20 and the console 30. Send and receive (details will be described later).
  • the electronic cassette 20 is not used only in the state of being held by the holding portion 42 of the standing base 34 or the holding portion 44 of the prone position base 36. When photographing, it can be used in a state where it is not held by the holding unit.
  • FIG. 3 is a schematic cross-sectional view schematically showing the configuration of the three pixel portions of the radiation detector 26 provided in the electronic cassette 20.
  • the radiation detector 26 includes a signal output unit 52, a sensor unit 54 (TFT substrate 74), and a scintillator 56 that are sequentially stacked on an insulating substrate 50.
  • the sensor unit 54 is provided with a pixel group of the TFT substrate 74. That is, the plurality of pixel groups are arranged in a matrix on the substrate 50, and the signal output unit 52 and the sensor unit 54 in each pixel are configured to overlap each other.
  • An insulating film 53 is interposed between the signal output unit 52 and the sensor unit 54.
  • the scintillator 56 is formed on the sensor unit 54 via a transparent insulating film 58, and forms a phosphor that emits light by converting radiation incident from above (opposite side of the substrate 50) or below into light. It is what. Providing such a scintillator 56 absorbs radiation transmitted through the subject and emits light.
  • the wavelength range of light emitted by the scintillator 56 is preferably in the visible light range (wavelength 360 nm to 830 nm), and in order to enable monochrome imaging by the radiation detector 26, the wavelength range of green is included. Is more preferable.
  • the phosphor used in the scintillator 56 preferably contains cesium iodide (CsI) when imaging using X-rays as radiation, and has an emission spectrum of 400 nm to 700 nm upon X-ray exposure. It is particularly preferred to use some CsI (Tl) (cesium iodide with thallium added). Note that the emission peak wavelength of CsI (Tl) in the visible light region is 565 nm.
  • CsI cesium iodide
  • the sensor unit 54 includes an upper electrode 60, a lower electrode 62, and a photoelectric conversion film 64 disposed between the upper and lower electrodes.
  • the photoelectric conversion film 64 absorbs light emitted from the scintillator 56 and generates electric charges. It is composed of an organic photoelectric conversion material.
  • the upper electrode 60 Since it is necessary for the upper electrode 60 to cause the light generated by the scintillator 56 to enter the photoelectric conversion film 64, it is preferable that the upper electrode 60 be made of a conductive material that is transparent at least with respect to the emission wavelength of the scintillator 56. It is preferable to use a transparent conductive oxide (TCO “Transparent Conductive Oxide”) having a high transmittance for visible light and a small resistance value. Although a metal thin film such as Au can be used as the upper electrode 60, the TCO is preferable because it tends to increase the resistance when it is desired to obtain a transmittance of 90% or more.
  • TCO Transparent Conductive Oxide
  • the upper electrode 60 may have a single configuration common to all pixels, or may be divided for each pixel.
  • the photoelectric conversion film 64 includes an organic photoelectric conversion material, absorbs light emitted from the scintillator 56, and generates electric charge according to the absorbed light.
  • the photoelectric conversion film 64 including the organic photoelectric conversion material has a sharp absorption spectrum in the visible region, and electromagnetic waves other than light emitted by the scintillator 56 are hardly absorbed by the photoelectric conversion film 64, and X-rays are obtained.
  • the noise generated by the radiation such as being absorbed by the photoelectric conversion film 64 can be effectively suppressed.
  • the organic photoelectric conversion material constituting the photoelectric conversion film 64 is preferably such that its absorption peak wavelength is closer to the emission peak wavelength of the scintillator 56 in order to absorb light emitted by the scintillator 56 most efficiently.
  • the absorption peak wavelength of the organic photoelectric conversion material matches the emission peak wavelength of the scintillator 56, but if the difference between the two is small, the light emitted from the scintillator 56 can be sufficiently absorbed.
  • the difference between the absorption peak wavelength of the organic photoelectric conversion material and the emission peak wavelength with respect to the radiation of the scintillator 56 is preferably within 10 nm, and more preferably within 5 nm.
  • Examples of the organic photoelectric conversion material that can satisfy such conditions include quinacridone organic compounds and phthalocyanine organic compounds.
  • quinacridone organic compounds since the absorption peak wavelength in the visible region of quinacridone is 560 nm, if quinacridone is used as the organic photoelectric conversion material and CsI (Tl) is used as the material of the scintillator 56, the difference in peak wavelength can be made within 5 nm. Thus, the amount of charge generated in the photoelectric conversion film 64 can be substantially maximized.
  • the sensor unit 54 constituting each pixel only needs to include at least the lower electrode 62, the photoelectric conversion film 64, and the upper electrode 60.
  • the electron blocking film 66 and the hole blocking film are used. It is preferable to provide at least one of 68, and it is more preferable to provide both.
  • the electron blocking film 66 can be provided between the lower electrode 62 and the photoelectric conversion film 64.
  • a bias voltage is applied between the lower electrode 62 and the upper electrode 60, electrons are transferred from the lower electrode 62 to the photoelectric conversion film 64. It is possible to suppress the dark current from increasing due to the injection of.
  • An electron donating organic material can be used for the electron blocking film 66.
  • the hole blocking film 68 can be provided between the photoelectric conversion film 64 and the upper electrode 60. When a bias voltage is applied between the lower electrode 62 and the upper electrode 60, the hole blocking film 68 is transferred from the upper electrode 60 to the photoelectric conversion film 64. It is possible to suppress the increase in dark current due to the injection of holes.
  • An electron-accepting organic material can be used for the hole blocking film 68.
  • the signal output unit 52 corresponds to the lower electrode 62, a capacitor 70 that accumulates the electric charge transferred to the lower electrode 62, and a field effect thin film transistor (Thin) that converts the electric charge accumulated in the capacitor 70 into an electric signal and outputs it.
  • Film-Transistor (hereinafter sometimes simply referred to as a thin film transistor) 72 is formed.
  • the region in which the capacitor 70 and the thin film transistor 72 are formed has a portion that overlaps the lower electrode 62 in plan view. With this configuration, the signal output unit 52 and the sensor unit 54 in each pixel are thick. There will be overlap in the vertical direction. In order to minimize the plane area of the radiation detector 26 (pixel), it is desirable that the region where the capacitor 70 and the thin film transistor 72 are formed is completely covered with the lower electrode 62.
  • FIG. 4 is a control block diagram of the imaging system 16 according to the present embodiment.
  • the console 30 functions as a server computer, and includes a display 80 for displaying an operation menu, a captured radiographic image, and the like, and an operation panel 82 for inputting various information and operation instructions. I have.
  • the console 30 includes a CPU 84 that controls the operation of the entire apparatus, a ROM 86 that stores various programs including a control program in advance, a RAM 87 that temporarily stores various data, and various data.
  • An HDD (Hard Disk Drive) 88 that stores and holds, a display driver 92 that controls display of various types of information on the display 80, and an operation input detector 90 that detects an operation state of the operation panel 82 are provided. .
  • the console 30 transmits and receives various information such as an exposure condition described later between the image processing device 23 and the radiation generation device 24 by wireless communication, and various types of image data and the like with the electronic cassette 20.
  • An I / F (for example, a wireless communication unit) 96 and an I / O 94 that transmit and receive information are provided.
  • the image processing device 23 may be included in the console 30.
  • the CPU 84, ROM 86, RAM 87, HDD 88, display driver 92, operation input detection unit 90, I / O 94, and wireless communication unit 96 are connected to each other via a bus 98 such as a system bus bus or a control bus. Therefore, the CPU 84 can access the ROM 86, RAM 87, and HDD 88, controls display of various information on the display 80 via the display driver 92, and the radiation generator 24 via the wireless communication unit 96. Control of transmission and reception of various types of information with the electronic cassette 20 can be performed. Further, the CPU 84 can grasp the operation state of the user with respect to the operation panel 82 via the operation input detection unit 90.
  • the image processing apparatus 23 includes an I / F (for example, a wireless communication unit) 100 that transmits and receives various types of information such as an exposure condition to and from the console 30, and the electronic cassette 20 and the radiation generation apparatus based on the exposure condition. 24, an image processing control unit 102 for controlling 24.
  • the radiation generator 24 includes a radiation exposure control unit 22 that controls radiation exposure from the radiation exposure source 22A.
  • the image processing control unit 102 includes a system control unit 104, a panel control unit 106, and an image processing control unit 108, and exchanges information with each other via a bus 110.
  • the panel control unit 106 receives information from the electronic cassette 20 wirelessly or by wire, and the image processing control unit 108 performs image processing.
  • the system control unit 104 receives information such as a tube voltage and a tube current as an exposure condition from the console 30 and, based on the received exposure condition, the radiation X from the radiation exposure source 22A of the radiation exposure control unit 22. Control to expose.
  • the imaging system 16 in the present embodiment has a function of automatically setting a region of interest.
  • control for setting the region of interest after radiographic imaging preparation control is performed. Is to be executed.
  • appropriate image information is obtained by performing feedback correction on the radiation dose of radiation exposed to the subject by ABC “Auto Brightness Control” control.
  • the principle of ABC control is that radiation exposure is performed so that the average value of one frame of the QL value generated based on the gradation signal received from the electronic cassette 20 converges to a predetermined threshold value (reference value). This is for adjusting the amount of radiation exposed from the radiation source 22A, for example, the same as the light amount adjustment by a digital camera or a movie camera.
  • the completion of the ROI setting is before the so-called main imaging, and particularly in the case of moving image shooting, it is preferable to suppress the radiation exposure dose to the subject until the ROI is determined after the ROI has been set.
  • FIG. 5 is a block diagram specialized in a control system for radiographic image capturing (including ROI setting) in the imaging system 16 (mainly the console 16, the image processing device 23, and the radiation generating device 24). Note that this block diagram categorizes radiographic image capturing control by function, and does not limit the hardware configuration. Therefore, the respective functional blocks may be distributed to the console 16, the image processing device 23, and the radiation generation device 24.
  • the radiation exposure control unit 22 exposes radiation from the radiation exposure source 22A based on the radiation dose adjusted by the radiation dose adjustment unit 120.
  • the radiation dose adjustment unit 120 adjusts the output radiation dose (energy), and details will be described later.
  • the radiation exposed from the radiation exposure source 22A passes through the subject 40 lying on the prone position table 36 and reaches the radiation detector 26 (see FIG. 3) of the electronic cassette 20.
  • the radiation detector 26 the phosphor film 56 (see FIG. 3) emits light having a light amount corresponding to the radiation amount and is photoelectrically converted by the TFT substrate 74.
  • the TFT substrate 74 of the electronic cassette 20 is connected to the signal acquisition unit 122.
  • the signal acquisition unit 122 acquires a signal photoelectrically converted based on the radiation exposed from the radiation exposure source 22 ⁇ / b> A and sends it to the gradation signal analysis unit 124.
  • the photoelectric conversion signal may be an analog signal or may be converted into a digital signal by the control unit in the electronic cassette 20.
  • a dynamic range adjustment unit 126 is connected to the gradation signal analysis unit 124.
  • the gradation signal analysis unit 124 based on the dynamic range compression parameter received from the dynamic range adjustment unit 126 (hereinafter referred to as "compression rate", the compression rate DRN in the normal state), the photoelectric conversion signal. Histogram analysis is performed. As a result, for example, as shown in FIG. 10A, a data count number (gradation signal) for each gradation (density) is obtained.
  • This gradation signal may be referred to as a QL value.
  • the QL value is the gradation signal itself (raw data), it is not the gradation signal itself, but, for example, the capacitor 70 (see FIG. 3) of the electronic cassette 20 or other circuit system capacitance. A value after correcting the noise component may be used as the QL value.
  • the gradation signal analysis unit 124 is connected to the purpose-specific still image generation instruction unit 125. In the gradation signal analysis unit 124, when the gradation signals for one frame have been prepared, the gradation signal analysis unit 124 sends them to the still image generation unit 128 via the purpose-specific still image generation instruction unit 125.
  • the purpose-specific still image generation instruction unit 125 determines whether it is generation of a still image for ROI setting or generation of a still image that is a basis for generating a moving image, and either instruction signal is stopped. The image is sent to the image generation unit 128. That is, the purpose-specific still image generation instruction unit 125 receives a ROI setting start signal or completion signal from a region-of-interest setting unit 138 described later. When the start signal is received, the still image generation unit 128 is instructed to generate a ROI setting still image. On the other hand, when the completion signal is received, the still image generation unit 128 is instructed to generate a still image for moving image editing.
  • the still image generation unit 128 generates a still image based on the gradation signals of the entire captured region in the case of ROI setting, and in the region of the set ROI (or in the ROI in the case of moving image editing). A still image is generated based on the gradation signal (including a part of the periphery in the region).
  • the still image generation unit 128 generates image data for each frame based on the received gradation signal.
  • the still image for moving image editing and the still image shooting for ROI setting differ in the photoelectric conversion signal itself sent from the electronic cassette 20, for example, as in this embodiment, the moving image editing
  • a binning process may be performed to give priority to the transfer rate.
  • image data based on the maximum number of pixels on the TFT substrate 74 is generated in order to prioritize image quality.
  • the still image generating unit 128 is connected to the moving image editing unit 130 and the region of interest setting unit 138.
  • the moving image editing unit 130 combines the image data for each frame sequentially transmitted from the still image generating unit 128 to edit the moving image.
  • the edited moving image is displayed on the display 80 via the display driver 92.
  • the still image generation unit 128 is connected to the display driver 92, and can display a still image on the display 80.
  • the moving image editing unit 130 is connected to the average QL value calculation unit 132.
  • the average QL value calculation unit 132 calculates the average value of the QL values of each frame (or one frame appropriately extracted) of the moving image.
  • the calculation result in the average QL value calculation unit 132 is sent to the ABC control unit 134.
  • a reference QL value memory 136 is connected to the ABC control unit 134.
  • the ABC control unit 134 compares the QL average value received from the average QL value calculation unit 132 with the reference QL value received from the reference QL value memory 136, and converges the QL average value to the reference QL value.
  • Correction information ⁇ X is generated. This correction information ⁇ X is applied as a correction coefficient for increasing or decreasing the radiation dose (energy) exposed from the radiation exposure source 22A.
  • the correction information ⁇ X generated by the ABC control unit 134 is sent to the radiation dose adjustment unit 120.
  • the radiation dose XN is increased or decreased (XN ⁇ XN ⁇ ⁇ X).
  • the radiation dose adjustment unit 120 stores an initial value of the radiation dose XN, and when the exposure instruction is given, the exposure is started from the initial value.
  • the photoelectric conversion signal that is the basis for generating the moving image can be within an appropriate range without excess or deficiency for obtaining the gradation signal. This means that it is a region where the rate of change in the characteristic diagram showing the correlation between the photoelectric conversion signal and the image density is large (for example, an intermediate region of the ⁇ curve in the case of a photosensitive material).
  • the correction information ⁇ X is used as a multiplication (division) coefficient when correcting the radiation dose XN, but an addition (subtraction) coefficient (XN ⁇ XN + ⁇ XN) may be used.
  • the region of interest setting unit 138 sets a region of interest (ROI) based on the ROI setting still image data received from the still image generating unit 128.
  • ROI region of interest
  • a general method is a method of surrounding pixels having a pixel value equal to or greater than a certain value, and is suitable for surrounding an organ or a lesion where radioactivity is accumulated.
  • an ROI is defined in advance in a standard image and is matched with a target image. Furthermore, in the case of a moving image, a portion with a large change amount may be extracted.
  • the region-of-interest setting unit 138 sets at least a start signal indicating the start of setting of the ROI and the setting completion to the still image generation instruction unit 125 for each purpose and the exposure control unit 140 before ROI determination
  • a completion signal indicating the time is output.
  • the purpose-specific still image generation instruction unit 125 recognizes the purpose of the still image based on the start signal or the completion signal.
  • the pre-ROI determination exposure control unit 140 is connected to the radiation dose adjustment unit 120, the ABC control unit 134, and the dynamic range adjustment unit 126, respectively.
  • the control prohibition signal for instructing prohibition of the ABC control is output from the pre-ROI determination exposure control unit 140 to the ABC control unit 134.
  • An instruction signal is output (XROI ⁇ XN).
  • the result of the histogram analysis of the photoelectric conversion signal in the modulation signal analysis unit 124 is a part of the set dynamic range (region with a low QL value). ) Only.
  • the compression rate of the dynamic range is the ROI whose compression rate is higher than the compression rate DRN from the compression rate DRN at the steady state.
  • a dynamic range compression ratio instruction signal that is an instruction for setting the compression ratio DRROI for setting is output (DRROI> DRN).
  • the result of the histogram analysis of the photoelectric conversion signal covers the entire dynamic range.
  • the radiation dose (energy) exposed from the radiation exposure source 22A is lowered (from the radiation dose XN to the radiation dose XROI), and the amount of the dynamic range is reduced.
  • the compression rate from the compression rate DRN to DRROI
  • a completion signal is sent to the still image generation instruction unit 125 for each purpose and the exposure control unit 140 before ROI determination, so that the captured still image is a moving image.
  • the radiation dose adjustment unit 120 sets the radiation dose to the initial value XN
  • the dynamic range adjustment unit 126 sets the compression rate to DRN.
  • ABC control by the ABC control unit 134 can be executed.
  • FIG. 6 is a flowchart showing the radiographic imaging preparation control routine.
  • step 200 it is determined whether or not a shooting instruction has been issued. If a negative determination is made, this routine ends. If an affirmative determination is made, the routine proceeds to step 202.
  • step 202 an initial information input screen is displayed. That is, the display driver 92 is controlled to display a predetermined initial information input screen on the display 80, and the process proceeds to step 204.
  • step 204 input of predetermined information is waited.
  • the name of the subject who will take a radiographic image, the part to be imaged, the posture at the time of radiography, and the exposure condition of the radiographic X at the time of radiography (in this embodiment, the radiation X is exposed Message for prompting the input of the tube voltage and tube current) and an input area for such information are displayed.
  • the photographer When the initial information input screen is displayed on the display 80, the photographer displays the name of the subject to be imaged, the region to be imaged, the posture at the time of imaging, and the exposure conditions in the corresponding input areas. Input via 82.
  • the radiographer enters the radiography room 32 together with the subject.
  • the radio cassette 20A is supported while the electronic cassette 20 is held in the holding unit 44 of the corresponding prone position table 36.
  • the subject is positioned (positioned) at a predetermined imaging position.
  • the subject and the electronic cassette 20 are ready to capture the imaging target site.
  • the radiation exposure source 22A is positioned (positioned).
  • step 204 is affirmative and the process proceeds to step 206.
  • the negative determination in step 204 is an infinite loop, but it may be forcibly terminated by operating a cancel button provided on the operation panel 82.
  • step 206 information input on the initial information input screen (hereinafter referred to as “initial information”) is transmitted to the electronic cassette 20 via the wireless communication unit 96, and then the process proceeds to the next step 208.
  • the exposure condition is set by transmitting the exposure condition included in the initial information to the radiation generator 24 via the wireless communication unit 96.
  • the image processing control unit 102 of the radiation generator 24 prepares for exposure under the received exposure conditions.
  • step 210 the start of the ABC control is instructed, and then the process proceeds to step 212, where the instruction information instructing the start of radiation exposure is transmitted to the radiation generator 24 via the wireless communication unit 96.
  • step 212 the instruction information instructing the start of radiation exposure is transmitted to the radiation generator 24 via the wireless communication unit 96.
  • the routine ends. The details of the ABC control in step 210 will be described later using the flowchart of FIG.
  • step 250 it is determined whether or not an exposure start instruction has been issued. If a negative determination is made, this routine ends. If an affirmative determination is made, the routine proceeds to step 252.
  • step 252 the region-of-interest setting control is executed, and when the region-of-interest setting ends, the process proceeds to step 254. Details of the region-of-interest setting control in step 252 will be described later using the flowchart of FIG.
  • step 254 the steady-state radiation dose (initial value) XN is read, and then the process proceeds to step 256 where the radiation exposure control unit 22 performs the exposure received by the radiation generator 24 from the console 30.
  • the emission of the radiation X from the radiation exposure source 22A with the tube voltage and the tube current according to the irradiation conditions is started.
  • the radiation X emitted from the radiation exposure source 22A reaches the electronic cassette 20 after passing through the subject.
  • the currently stored radiation dose correction information is read out.
  • This radiation dose correction information is generated by ABC control and is stored as a correction coefficient ⁇ X.
  • correction processing based on ABC control is executed. That is, based on the gradation signal (QL value) obtained from the electronic cassette 20, an average value of the QL values of the region of interest image is calculated, and the average value of the QL values is compared with a predetermined threshold value. The radiation dose is feedback controlled so as to converge to the threshold value.
  • step 262 the moving image editing process is executed, and the edited moving image is displayed on the display 80 in step 264 (image display process).
  • step 266 image data (moving image data) is transmitted to the RIS server 14 (see FIG. 1) via the in-hospital network 18, and the process proceeds to step 268.
  • step 268 it is determined whether or not an instruction to end imaging is given. If an affirmative determination is made, exposure is terminated in step 270, and the radiographic image capturing control program is terminated.
  • the corrected image data transmitted to the RIS server 14 is stored in the database 14A, so that a doctor can perform radiogram image interpretation and diagnosis.
  • step 210 of FIG. 6 the flow of ABC control that is instructed and started in step 210 of FIG. 6 will be described with reference to FIG. Note that the ABC control routine of FIG. 8 may be executed independently of the flowcharts of FIGS.
  • step 300 it is determined whether or not the exposure control after the ROI is determined. This is determined based on an ABC control prohibition instruction in Step 320 and an ABC control prohibition release instruction in Step 338, which will be described later.
  • step 300 If a negative determination is made in step 300, it is determined that ROI is being set, and this routine ends. That is, ABC control is not executed.
  • step 300 If the determination in step 300 is affirmative, the process proceeds to step 302 to set the dynamic range compression ratio to the compression ratio DRN at the normal time, and then the process proceeds to step 304 to capture image data, and the process proceeds to step 306. .
  • step 306 the average QL value is calculated from the captured image data, and then the process proceeds to step 308 to read the reference QL value.
  • the average QL value from the captured image data is compared with the read reference QL value to determine whether correction is possible, and the process proceeds to step 312.
  • the determination as to whether correction is possible may be a so-called on / off determination in which a predetermined amount of correction is performed if the difference is greater than or equal to a predetermined value and no correction is made if the difference is less than a predetermined value.
  • the solution of the calculation by a predetermined arithmetic expression (for example, arithmetic expression based on PID control etc.) may be sufficient.
  • step 312 correction information ⁇ X of the radiation dose XROI is generated based on the comparison and determination results in step 310, and then the process proceeds to step 314 to store the correction information ⁇ X generated in step 312. Ends.
  • FIG. 9 is a flowchart showing a region-of-interest setting control routine executed in step 252 of FIG. When execution of this region-of-interest setting control routine is started, a start signal is output to the exposure control unit 240 before ROI determination.
  • step 320 first, prohibition of ABC control is instructed. As a result, the radiation dose exposed from the radiation exposure source 22A is constant without feedback control.
  • the radiation dose XROI at the time of region of interest setting is read.
  • This region-of-interest setting radiation dose XROI is lower than the steady-state radiation dose N (XROI ⁇ XN).
  • the dynamic range compression ratio DRROI is read when the region of interest is set.
  • This region-of-interest setting dynamic range compression rate DRROI is a compression rate higher than a predetermined dynamic range compression rate DRN (hereinafter referred to as “steady-state dynamic range DRN”) (DRROI> DRN).
  • step 326 pre-exposure is started with the radiation dose XROI, and the process proceeds to step 328.
  • step 328 a still image for ROI setting is generated based on the photographing data (gradation signal) obtained by the pre-exposure in step 326, and the process proceeds to step 330.
  • step 330 the start of ROI setting is instructed, and the process proceeds to step 332. Since the pre-exposure in step 326 is an exposure for a still image, the radiation dose XROI is not accumulated except for a short time during the pre-exposure.
  • step 332 image display processing is executed, and the process proceeds to step 334.
  • step 334 it is determined whether or not the region of interest can be set from the moving image. If a negative determination is made, the process returns to step 332 and the image display is continued. If the determination in step 334 is affirmative, it is determined that the ROI setting has been completed, the process proceeds to step 338, the prohibition of ABC control is canceled, and this routine ends.
  • the histogram when the photoelectric conversion signal under the radiation dose XN in the steady state is converted into the gradation signal is almost the entire dynamic range compression rate DRN region in the steady state. It is distributed over. In other words, when setting the dynamic range compression ratio DRN at the normal time, the prediction is made based on the radiation dose XN at the normal time.
  • FIGS. 10 (2) and 11 (1) are the same characteristic diagram).
  • step 324 in FIG. 9 the dynamic range compression ratio is increased (DRROI).
  • DRROI dynamic range compression ratio
  • the radiation dose exposed from the radiation exposure source 22A is suppressed as much as possible (lower than the normal time), and the QL based on the lowered radiation dose is set.
  • the dynamic range compression rate was set higher than in the steady state to match the distribution of the value gramogram. For this reason, even if the distribution of the QL value is biased, the dynamic range can be used without waste, and both reduction of the exposure dose of the subject due to the radiation dose reduction and high-precision ROI setting can be achieved.
  • the radiation filter is temporarily (during pre-exposure) with the subject without changing the radiation dose from the radiation exposure source 22A. May be interposed.
  • the radiation filter includes, for example, a so-called diaphragm mechanism that can be installed on the radiation surface of the radiation radiation source 22A.
  • a so-called diaphragm mechanism that can be installed on the radiation surface of the radiation radiation source 22A.
  • attaching an ND (darkening) filter to the range and adjusting the aperture are the same in terms of the role of adjusting (reducing) exposure.
  • ND darkening
  • the diaphragm mechanism is a substitute for a case where the radiation filter cannot be practically used depending on the type of radiation. Applicable.
  • the radiation detector 26 in the electronic cassette 20 is a so-called area sensor in which detection pixels are two-dimensionally arranged, but only for a moving image that does not require a higher frame rate than a still image, Newly equipped with a line sensor in which pixels in the main scanning direction are arranged and a scanning mechanism unit that moves the line sensor in the sub-scanning direction, and a function of acquiring a two-dimensional image in time series by scanning of the scanning mechanism unit An electronic cassette may be manufactured. Further, a line sensor and a scanning mechanism unit may be built in the standing table 42 or the standing table 36 shown in FIG.
  • a line sensor for example, after a region of interest (ROI) is set, if a moving image is specified in the ROI region, at least the sub-scanning range can be reduced. Can be reduced.
  • ROI region of interest
  • FIG. 12 is a characteristic diagram in the case where the accumulated value of the exposure dose in the process of performing the examination by moving image for the subject in the radiographic imaging system 16 according to the present embodiment is compared with the conventional comparative example. It is.
  • the exposure amount is based on the inclination (change rate) of the present embodiment. It can be seen that a large slope (change rate) is accumulated in a so-called right-up direction (see the chain line in FIG. 12). Moreover, at the end of the inspection, ABC control increases in a quadratic curve in addition to a direct proportional (primary curve) increase, and a large gap occurs between the primary curve and the quadratic curve.
  • a still image is captured by pre-exposure prior to moving image capturing, and an ROI is set based on the still image generated by the pre-exposure, Until the ROI setting is completed, the ABC control is prohibited, so that the exposure dose can be significantly reduced as compared with the exposure dose during the ROI setting while always performing the moving image shooting and the ABC control. Furthermore, since the radiation energy in the pre-exposure for ROI setting is set low and the compression ratio of the dynamic range for converting to the gradation signal is increased accordingly, the ROI can be accurately and quickly performed even if the exposure dose is low. Can be set.

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Abstract

In the present radiography system, a still image is captured by means of a pre-exposure ahead of moving picture imaging, and on the basis of the still image resulting from the pre-exposure, an ROI is set, and ABC control is prohibited until ROI setting is complete. Furthermore, the radiation energy in the pre-exposure for ROI setting is set at a low level, and the compression rate of a dynamic range for conversion to a gradient signal is set correspondingly higher.

Description

放射線動画像撮影装置、放射線動画像撮影装置用関心領域設定方法、放射線画像撮影システム、放射線動画像撮影制御プログラムRadiation moving image capturing apparatus, region of interest setting method for radiation moving image capturing apparatus, radiation image capturing system, radiation moving image capturing control program
　本発明は、被検者に向けて放射線を曝射し、被検体を通過した放射線量を放射線検出器で受けて得た静止画像を連続的に撮影することで被検体の動画像を生成する射線動画像撮影装置、放射線動画像撮影装置用関心領域設定方法、放射線画像撮影システム、放射線動画像撮影制御プログラムに関するものである。 The present invention generates a moving image of a subject by continuously radiating radiation toward the subject and continuously capturing still images obtained by receiving a radiation amount passing through the subject with a radiation detector. The present invention relates to a radiation moving image capturing apparatus, a region of interest setting method for a radiation moving image capturing apparatus, a radiation image capturing system, and a radiation moving image capturing control program.
　近年、ＴＦＴ（Thin Film Transistor）アクティブマトリクス基板上に放射線感応層を配置し、放射線量をデジタルデータ（電気信号）に変換できるＦＰＤ（Flat Panel Detector）等の放射線検出器（「電子カセッテ」等という場合がある）が実用化されており、この放射線検出器を用いて、曝射された放射線量により表わされる放射線画像を撮影する放射線画像撮影装置が実用化されている。 In recent years, radiation detectors such as FPD (Flat Panel Detector) that can arrange radiation sensitive layers on TFT (Thin Film Transistor) active matrix substrates and convert radiation dose into digital data (electrical signals) (referred to as “electronic cassettes”) In some cases, a radiation image capturing apparatus that captures a radiation image represented by the amount of radiation that has been exposed using this radiation detector has been put into practical use.
　なお、放射線量は、例えば、互換をもって発光量に変換され、その後、電気信号に変換される間接変換方式と、放射線量から直接電気信号に変換される直接変換方式とがあり、適宜選択して採用される。 The radiation dose is, for example, interchangeably converted into a light emission amount and then converted into an electric signal, and then a direct conversion method in which the radiation dose is directly converted into an electric signal, and is selected as appropriate. Adopted.
　ところで、上記のような放射線画像撮影装置では、一定時間毎に放射線検出器で検出した画像情報を連続して再生することで、所謂動画像を表示することが考えられている。なお、一定時間の間隔は、短ければ短いほど連続性が向上して、動画像としての画質がよいが、その分画像情報量が増えることになるのは、一般のＣＣＤやＣＭＯＳ等を用いた撮像装置（イメージセンサ）と同様である。放射線画像撮影装置においては、撮影する画像コマ数が増えれば、被検者への放射線量が増えることになるため、適切な画像コマ数を選択することが好ましい。なお、「適切な画像コマ数」とは、撮影対象（被検者における関心領域（ＲＯＩ）内の画像）の動きが速いか遅いか、当該動きの変化量を重視するか否か等、撮影目的に合わせて決めた画像コマ数である。 By the way, in the radiographic imaging apparatus as described above, it is considered to display a so-called moving image by continuously reproducing image information detected by a radiation detector at regular intervals. Note that the shorter the time interval, the better the continuity and the better the image quality as a moving image. However, the amount of image information is increased by using a general CCD or CMOS. It is the same as an imaging device (image sensor). In the radiographic image capturing apparatus, if the number of image frames to be captured increases, the radiation dose to the subject increases. Therefore, it is preferable to select an appropriate number of image frames. The “appropriate number of image frames” refers to whether the movement of the imaging target (image in the region of interest (ROI) in the subject) is fast or slow, whether or not the change amount of the movement is important, etc. This is the number of image frames decided according to the purpose.
　一方、放射線画像撮影装置では、動画像を撮影する場合、撮影した画像情報に基づき、放射線量を制御して、放射線検出器による検出状態を最適に維持するフィードバック制御（ＡＢＣ「Auto Brightness Control」制御）が必須である。 On the other hand, in the radiographic imaging device, when capturing a moving image, feedback control (ABC “Auto Brightness Control” control is performed to control the radiation dose based on the captured image information and optimally maintain the detection state by the radiation detector. ) Is essential.
　特開２０１０-２７３８３４号公報には、造影血管の透視画像及びＤＡ（Digital Angiography）画像を表示するＸ線画像診断装置が開示されている。 Japanese Patent Laid-Open No. 2010-273434 discloses an X-ray diagnostic imaging apparatus that displays a fluoroscopic image of a contrasted blood vessel and a DA (Digital Angiography) image.
　また、特開平９-２６６９０１号公報には、放射線画像の画像処理条件設定装置が開示されている。 Japanese Patent Laid-Open No. 9-266901 discloses an image processing condition setting device for radiographic images.
　特開２０１０-２７３８３４号公報には、関心領域内の画像レベルに基づいてＡＢＣ制御を行うＸ線画像診断装置において、ユーザ操作に応じて、ＡＢＣ制御を適宜解除して、そのときのＸ線条件を固定することができる技術が開示されている。 Japanese Patent Application Laid-Open No. 2010-27383 discloses an X-ray diagnostic imaging apparatus that performs ABC control based on an image level in a region of interest by appropriately canceling ABC control according to a user operation, and the X-ray condition at that time A technique that can fix the above is disclosed.
　ここで、放射線画像撮影装置による動画像撮影では、当然静止画撮影に比べて被検者（検査を受ける者）への被曝量が多くなる傾向にある。このため、当該被曝量を軽減することが重要な課題である。 Here, naturally, moving image shooting by a radiographic imaging device tends to increase the amount of exposure to a subject (a person undergoing an examination) compared to still image shooting. For this reason, reducing the exposure dose is an important issue.
　被曝量を軽減するためには、放射線発生装置からの放射される放射線量を減らせばよいが、現状では、前記関心領域が確定する以前から、前記ＡＢＣ制御が実行されており、このＡＢＣ制御に起因して、所謂本撮影前の画像であるにも関わらず、放射線量が増大する方向に制御される場合がある。 In order to reduce the exposure dose, the radiation dose emitted from the radiation generating device may be reduced. However, at present, the ABC control is executed before the region of interest is determined. As a result, the radiation dose may be controlled to increase in spite of the so-called pre-photographing image.
　これを解消するために、ＡＢＣ制御を解除すると共に、放射線発生装置からの放射線量を低線量とすれば、無用な放射線量が出力されずに、関心領域を特定することが可能となる。 In order to solve this problem, if the ABC control is canceled and the radiation dose from the radiation generator is set to a low dose, it becomes possible to specify the region of interest without outputting unnecessary radiation dose.
　なお、前記特開２０１０-２７３８３４号公報に記載された技術は、ＡＢＣ制御を解除することが記載されているが、当該ＡＢＣ制御を解除するタイミングとしては、直接Ｘ線を検出する部位を撮影する場合などとしており、作用効果が異なる。また、特許文献１は、ユーザ操作に応じてＡＢＣ制御を解除するものであり、ＡＢＣ制御と関心領域との因果関係はない。 The technique described in Japanese Patent Application Laid-Open No. 2010-273834 describes that the ABC control is cancelled. However, as a timing for canceling the ABC control, a part for directly detecting X-rays is imaged. The effect is different. Further, Patent Document 1 cancels ABC control according to a user operation, and there is no causal relationship between ABC control and a region of interest.
　また、参考として、特開２００９－１０１２０８号公報には、ＡＢＣ制御を行うものではないが、関心領域を設定するための最初の曝射時には通常どおり撮影を行い、撮影して得られた画像上で関心領域を設定した後は、関心領域のみ放射線が曝射されるようにコリメータを制御する技術が開示されている。 For reference, Japanese Patent Laid-Open No. 2009-101208 does not perform ABC control, but performs normal shooting at the time of the first exposure for setting a region of interest. After setting the region of interest, a technique for controlling the collimator so that only the region of interest is exposed to radiation is disclosed.
　しかしながら、ＡＢＣ制御の解除、並びに低放射線量の下では、放射線検出器で検出する光量自体が少なくなるため、通常のダイナミックレンジでの検出では、所謂露出不足と同等の現象となり、関心領域の特定要素（特定までの所要時間、特定された領域の信頼性等）に影響を及ぼすことになる。 However, under the cancellation of ABC control and a low radiation dose, the amount of light detected by the radiation detector itself is small. Therefore, detection in the normal dynamic range is a phenomenon equivalent to so-called underexposure, and the region of interest is specified. Factors (time required until identification, reliability of the identified area, etc.) will be affected.
　ここで、放射線撮像分野において、関心領域を明瞭に認識可能とする目的でダイナミックレンジの圧縮を行うものとしては、例えば特開平９-２６６９０１号公報のように、関心領域である脊椎全体を表現するのに適したダイナミックレンジ圧縮を行うものなどがある。ただし、ＡＢＣ制御とダイナミックレンジの圧縮との因果関係はない。 Here, in the field of radiation imaging, as a method for performing dynamic range compression for the purpose of clearly recognizing the region of interest, the entire spine that is the region of interest is expressed as in, for example, Japanese Patent Laid-Open No. 9-266901. There is one that performs dynamic range compression suitable for the above. However, there is no causal relationship between ABC control and dynamic range compression.
　本発明は上記事実を考慮し、主として動画像撮影する場合に、関心領域の特定に悪影響を及ぼすことなく、被検者への放射線被曝量を低減することができる放射線動画像撮影装置、放射線動画像撮影装置用関心領域設定方法、放射線画像撮影システム、放射線動画像撮影制御プログラムを得ることが目的である。 In consideration of the above-described facts, the present invention mainly provides a moving image radiographing apparatus and a radiographic moving image capable of reducing the radiation exposure dose to a subject without adversely affecting the identification of a region of interest when capturing a moving image. It is an object to obtain a region-of-interest setting method for an image capturing apparatus, a radiation image capturing system, and a radiation moving image capturing control program.
　第１の発明は、設定された定常範囲の放射線エネルギーの放射線を、被検体に向けて曝射する放射線曝射手段から曝射され、かつ前記被検体を通過した放射線量を、複数の画素を備えた放射線検出器で受け、当該画素毎に受ける放射線量に応じた階調信号を出力する放射線画像撮影手段と、前記放射線画像撮影手段から階調信号を取得して、所定のダイナミックレンジの下で当該階調信号を読み取り、１フレーム毎の静止画像情報を生成すると共に、前記静止画像を連続的に撮影することで前記被検体の動画像を生成する動画像情報生成手段と、
　所定の制御周期で、前記放射線曝射手段から曝射する前記放射線の放射線エネルギーの設定値をフィードバック制御する制御手段と、前記制御手段によるフィードバック制御禁止を指示し、かつ前記放射線曝射手段を指示して静止画像用のプレ曝射を実施し、前記放射線画像撮影手段から前記プレ曝射に基づく少なくとも１フレーム分の静止画像に相当する階調信号を取得し、当該階調信号から生成される静止画像の一部の領域を関心領域として設定する関心領域設定手段と、を有している。 According to a first aspect of the present invention, a plurality of pixels are used to determine the amount of radiation that has been emitted from radiation exposure means that exposes radiation of radiation energy in a set steady range toward a subject and has passed through the subject. A radiation image capturing unit that receives a radiation signal in accordance with the amount of radiation received for each pixel received by the radiation detector provided, and obtains the gradation signal from the radiation image capturing unit, and has a predetermined dynamic range. Reading the gradation signal, generating still image information for each frame, and moving image information generating means for generating a moving image of the subject by continuously capturing the still images;
Control means for feedback controlling the set value of the radiation energy of the radiation to be emitted from the radiation exposure means at a predetermined control cycle, instructing prohibition of feedback control by the control means, and instructing the radiation exposure means Then, pre-exposure for a still image is performed, and a gradation signal corresponding to a still image for at least one frame based on the pre-exposure is acquired from the radiation image capturing unit, and generated from the gradation signal. A region of interest setting means for setting a partial region of the still image as a region of interest.
　第１の発明によれば、通常の動画像撮影の手順としては、放射線曝射手段により、設定された定常範囲の放射線エネルギーの放射線を、被検体に向けて曝射する。 According to the first aspect of the present invention, as a normal moving image capturing procedure, radiation of radiation energy in a set steady range is exposed toward the subject by the radiation exposure means.
　放射線画像撮影手段では、放射線曝射手段から曝射され、かつ被検体を通過した放射線量を、複数の画素を備えた放射線検出器で受け、当該画素毎に受ける放射線量に応じた階調信号を出力する。 In the radiographic image capturing means, the radiation amount irradiated from the radiation exposure means and passed through the subject is received by a radiation detector having a plurality of pixels, and a gradation signal corresponding to the radiation amount received for each pixel Is output.
　次に、動画像情報生成手段では、放射線画像撮影手段から階調信号を取得して、予め定めた定常ダイナミックレンジの下で当該階調信号を読み取り、１フレーム毎の静止画像情報を生成すると共に、静止画像を連続的に撮影することで被検体の動画像を生成する。 Next, the moving image information generating means acquires the gradation signal from the radiation image photographing means, reads the gradation signal under a predetermined steady dynamic range, and generates still image information for each frame. Then, a moving image of the subject is generated by continuously capturing still images.
　この場合、制御手段では、所定の制御周期で、前記放射線曝射手段から曝射する前記放射線の放射線エネルギーの設定値をフィードバック制御する。 In this case, the control means feedback-controls the set value of the radiation energy of the radiation exposed from the radiation exposure means at a predetermined control cycle.
　ここで、撮影指示直後は、関心領域設定手段において、撮影される動画像の中から関心領域を設定する。 Here, immediately after the photographing instruction, the region of interest setting means sets the region of interest from the moving images to be photographed.
　このとき、関心領域設定手段では、制御手段によるフィードバック制御を禁止すると共に、動画像撮影に先だって、プレ曝射により静止画像を撮影する。この静止画像に基づいて、画像の一部を関心領域として設定する。 At this time, the region-of-interest setting unit prohibits feedback control by the control unit and captures a still image by pre-exposure prior to moving image capturing. Based on this still image, a part of the image is set as a region of interest.
　このため、所謂本撮影（動画撮影）ではない関心領域設定期間は、被検体に対して曝射されるのは、静止画像の撮影時のみであり、被検体の被曝量を定常範囲よりも抑制することができる。また、フィードバック制御を禁止することで、抑制した状態を維持することができる。 Therefore, during the region-of-interest setting period that is not so-called main imaging (video imaging), the subject is exposed only during still image shooting, and the exposure dose of the subject is suppressed from the normal range. can do. Moreover, the state which was suppressed can be maintained by prohibiting feedback control.
　第１の発明において、前記関心領域設定手段により前記関心領域が設定された後は、前記制御手段によるフィードバック制御禁止を解除すると共に、前記動画像の生成を開始する。 In the first invention, after the region of interest is set by the region of interest setting means, the prohibition of feedback control by the control means is canceled and the generation of the moving image is started.
　放射線曝射手段からの放射線を、必要最小限に抑えることができるので、被検体はもちろん、周囲の環境に対しても十分な配慮を施すことができる。 Since radiation from the radiation exposure means can be minimized, sufficient consideration can be given not only to the subject but also to the surrounding environment.
　第１の発明において、前記放射線曝射手段による前記プレ曝射時の静止画像の撮影による被曝量が、前記動画像の撮影中の１フレーム分の静止画像の生成時の被曝量よりも抑制される。 In the first aspect of the invention, the exposure dose due to still image shooting during the pre-exposure by the radiation exposure means is suppressed to be less than the exposure dose during generation of a still image for one frame during shooting of the moving image. The
　プレ曝射による静止画像は、関心領域を設定することのみに適用されるため、例えば、被検体の患部を精密に観察するほどの画質を持つ画像（高画質静止画像）は不要であり、この適用目的の差分だけ、曝射量を抑制することができる。 Since the still image by pre-exposure is applied only to setting the region of interest, for example, an image having high image quality (high-quality still image) enough to accurately observe the affected area of the subject is unnecessary. The amount of exposure can be suppressed by the difference in application purpose.
　第１の発明において、前記被曝量の抑制が、前記放射線曝射手段に対して指示する放射線エネルギーを定常範囲よりも低くすることである。 In the first invention, the suppression of the exposure dose is to make the radiation energy instructed to the radiation exposure means lower than a steady range.
　放射線の発生源自体の放射線エネルギーを定常範囲よりも低くすることで、被検体への被曝量を低減することができる。 The exposure dose to the subject can be reduced by making the radiation energy of the radiation source itself lower than the steady range.
　第１の発明において、前記被曝量が抑制され、かつ前記フィードバック制御が禁止されている間は、前記ダイナミックレンジの圧縮のパラメータである前記階調信号に対する前記画像情報の変化率を、フィードバック制御中よりも大きくするように調整する。 In the first invention, while the exposure dose is suppressed and the feedback control is prohibited, the rate of change of the image information with respect to the gradation signal which is a parameter of compression of the dynamic range is being feedback controlled. Adjust to make it larger.
　放射線曝射手段に対して指示する放射線エネルギーを定常範囲よりも低くしていると、画素毎に検出する放射線量自体が少なくなり、階調信号を適正に得ることができない場合がある。 If the radiation energy instructed to the radiation exposure means is set lower than the steady range, the radiation amount itself detected for each pixel decreases, and a gradation signal may not be obtained properly.
　そこで、ダイナミックレンジの圧縮のパラメータを、フィードバック制御中のダイナミックレンジの圧縮のパラメータよりも大きくする。 Therefore, the dynamic range compression parameter is made larger than the dynamic range compression parameter during feedback control.
　ダイナミックレンジの圧縮のパラメータとは、階調信号に対する画像情報の変化率であり、放射線エネルギーが低い分、放射線検出器で受ける放射線量が少なく、階調信号は低レベル側に偏る傾向となり、階調変化（濃度変化）が低い。この偏った領域に合わせて、ダイナミックレンジの圧縮のパラメータ、すなわち階調信号に対する画像情報の変化率を大きくすることで、所謂アンダー気味の画像から適正な画像情報を得ることができる。 The dynamic range compression parameter is the rate of change of the image information with respect to the gradation signal. The radiation dose received by the radiation detector is small because the radiation energy is low, and the gradation signal tends to be biased toward the low level. Tonal change (density change) is low. Appropriate image information can be obtained from a so-called underimage by increasing the dynamic range compression parameter, that is, the rate of change of the image information with respect to the gradation signal, in accordance with this biased region.
　第１の発明において、前記関心領域設定手段で関心領域を設定する際に適用する静止画像の範囲が、前記関心領域設定後に撮影する動画像の範囲よりも広い範囲である。 In the first invention, the range of the still image applied when the region of interest is set by the region of interest setting means is wider than the range of the moving image captured after the region of interest is set.
　関心領域を設定する場合、関心領域対象となる静止画像の範囲を、関心領域設定後に撮影する動画像の範囲よりも広くする。これにより、関心領域の見逃し、誤認等を防止することができる。 When setting the region of interest, the range of the still image that is the target of the region of interest is made wider than the range of moving images that are captured after the region of interest is set. As a result, it is possible to prevent the region of interest from being overlooked or misidentified.
　第１の発明において、前記制御手段によるフィードバック制御の対象が、前記関心領域設定手段により設定された関心領域内の画像とする。 In the first invention, the target of feedback control by the control means is an image in the region of interest set by the region of interest setting means.
　例えば、関心領域内外で区別して放射線量を調整することができれば、関心領域内は適正な放射線エネルギーとなるようにフィードバック補正し、関心領域外は放射線量を低くすることで、被検体へ曝射される放射線量を低減することができる。 For example, if the radiation dose can be adjusted separately inside and outside the region of interest, feedback correction is performed so that appropriate radiation energy is obtained within the region of interest, and the radiation dose is reduced outside the region of interest, thereby exposing the subject. The amount of radiation emitted can be reduced.
　関心領域内外で区別して放射線量を調整する手段としては、例えば、放射線曝射手段の曝射面を区画して独立して制御する、或いは、前記放射線曝射手段と前記被検者との間に、アパーチャーを配置する等の手段が考えられ、動画像の場合、関心領域の移動に追従させればよい。 As a means for adjusting the radiation dose by distinguishing between the inside and outside of the region of interest, for example, the exposure surface of the radiation exposure means is partitioned and controlled independently, or between the radiation exposure means and the subject. In addition, means such as arranging an aperture can be considered, and in the case of a moving image, the movement of the region of interest may be followed.
　第２の発明は、放射線エネルギーの連続曝射による動画像撮影に先だって、被検体に向けて、静止画像用のプレ曝射を行い、前記プレ曝射により前記被検体を通過する放射線エネルギーに基づいて、所定のダイナミックレンジの下で、少なくとも１フレーム分の静止画像に相当する階調信号を取得し、当該階調信号から生成される静止画像の一部の領域を関心領域として設定し、当該関心領域を設定した後、所定の制御周期で、曝射する放射線の放射線エネルギーの設定値をフィードバック制御する処理を開始すると共に、動画像の撮影を開始する。 According to a second aspect of the present invention, pre-exposure for a still image is performed toward a subject prior to moving image capturing by continuous exposure of radiation energy, and based on radiation energy passing through the subject by the pre-exposure. Acquiring a gradation signal corresponding to a still image of at least one frame under a predetermined dynamic range, setting a partial region of the still image generated from the gradation signal as a region of interest, After setting the region of interest, a process for feedback control of the set value of the radiation energy of the radiation to be exposed is started at a predetermined control cycle, and moving image capturing is started.
　第２の発明によれば、例えば、通常の動画像撮影の手順としては、設定された定常範囲の放射線エネルギーの放射線を、被検体に向けて曝射し、かつ被検体を通過した放射線量に応じた階調信号を所定のダイナミックレンジの下で読み取り、１フレーム毎の静止画像情報を生成すると共に、静止画像を連続的に撮影することで被検体の動画像を生成する。 According to the second aspect of the invention, for example, as a normal moving image capturing procedure, radiation of radiation energy in a set steady range is exposed toward the subject and the amount of radiation that has passed through the subject. A corresponding gradation signal is read under a predetermined dynamic range to generate still image information for each frame, and a moving image of the subject is generated by continuously capturing still images.
　この場合、所定の制御周期で、曝射する放射線の放射線エネルギーの設定値をフィードバック制御する。 In this case, the set value of the radiation energy of the radiation to be exposed is feedback-controlled at a predetermined control cycle.
　ここで、撮影指示直後は、撮影される動画像の中から関心領域を設定する。この関心領域設定中は、フィードバック制御を禁止すると共に、被検体の被曝量を定常範囲よりも抑制した状態で、画像の一部を関心領域として設定する。 Here, immediately after the shooting instruction, the region of interest is set from the moving images to be shot. During the region-of-interest setting, feedback control is prohibited and a part of the image is set as the region of interest while the exposure dose of the subject is suppressed from the steady range.
　関心領域設定は、フィードバック制御を禁止すると共に、動画像撮影に先だって、プレ曝射により静止画像を撮影する。この静止画像に基づいて、画像の一部を関心領域として設定する。 In the region of interest setting, feedback control is prohibited and still images are captured by pre-exposure prior to moving image capturing. Based on this still image, a part of the image is set as a region of interest.
　このため、所謂本撮影（動画撮影）ではない関心領域設定期間は、被検体に対して曝射されるのは、静止画像の撮影時のみであり、被検体の被曝量を定常範囲よりも抑制することができる。また、フィードバック制御を禁止することで、抑制した状態を維持することができる。 Therefore, during the region-of-interest setting period that is not so-called main imaging (video imaging), the subject is exposed only during still image shooting, and the exposure dose of the subject is suppressed from the normal range. can do. Moreover, the state which was suppressed can be maintained by prohibiting feedback control.
　第２の発明において、前記プレ曝射時の放射線の放射線エネルギーが、動画像撮影時よりも低く設定される。 In the second invention, the radiation energy of the radiation at the time of the pre-exposure is set lower than that at the time of moving image shooting.
　プレ曝射時は、放射線の発生源自体の放射線エネルギーを定常範囲よりも低くすることで、被検体への被曝量を低減することができる。 During pre-exposure, the radiation dose to the subject can be reduced by making the radiation energy of the radiation source itself lower than the steady range.
　第２の発明において、放射線エネルギーが低く設定された分、当該放射線エネルギーに対する階調信号の変化量が大きくなるように前記ダイナミックレンジの圧縮率を調整する。 In the second aspect of the invention, the compression ratio of the dynamic range is adjusted so that the change amount of the gradation signal with respect to the radiation energy is increased by the amount that the radiation energy is set low.
　放射線エネルギーを定常範囲よりも低くしていると、画素毎に検出する放射線量自体が少なくなり、階調信号を適正に得ることができない場合がある。 If the radiation energy is lower than the steady range, the amount of radiation detected for each pixel decreases, and a gradation signal may not be obtained properly.
　そこで、ダイナミックレンジの圧縮のパラメータを、フィードバック制御中のダイナミックレンジの圧縮のパラメータよりも大きくする。 Therefore, the dynamic range compression parameter is made larger than the dynamic range compression parameter during feedback control.
　ダイナミックレンジの圧縮のパラメータとは、階調信号に対する画像情報の変化率であり、放射線エネルギーが低い分、放射線検出器で受ける放射線量が少なく、階調信号は低レベル側に偏る傾向となり、階調変化（濃度変化）が低い。この偏った領域に合わせて、ダイナミックレンジの圧縮のパラメータ、すなわち階調信号に対する画像情報の変化率を大きくすることで、所謂アンダー気味の画像から適正な画像情報を得ることができる。 The dynamic range compression parameter is the rate of change of the image information with respect to the gradation signal. The radiation dose received by the radiation detector is small because the radiation energy is low, and the gradation signal tends to be biased toward the low level. Tonal change (density change) is low. Appropriate image information can be obtained from a so-called underimage by increasing the dynamic range compression parameter, that is, the rate of change of the image information with respect to the gradation signal, in accordance with this biased region.
　第３の発明は、前記第１～６の発明の何れか１つの放射線動画像撮影装置と、診断情報や施設予約の入力、閲覧、並びに放射線動画像の撮影依頼や撮影予約を行う端末装置と、前記端末装置からの撮影依頼を受け付け、前記放射線動画像撮影装置における放射線画像の撮影スケジュールを管理すると共に、撮影された放射線動画像を一括管理するサーバーと、を有する放射線画像撮影システムである。 According to a third aspect of the present invention, there is provided the radiological moving image capturing apparatus according to any one of the first to sixth aspects of the present invention, a terminal apparatus that inputs and browses diagnostic information and facility reservations, and requests radiographic image capturing and reservations. A radiographic imaging system comprising: a server that accepts an imaging request from the terminal device, manages a radiographic imaging schedule in the radiographic video imaging device, and collectively manages radiographic images taken.
　第３の発明によれば、特に病院内における、放射線科部門内において、診療予約、診断記録等の情報管理を行うためのシステムとして適用可能であり、病院情報システムの一部となり得る。 According to the third aspect of the invention, it can be applied as a system for managing information such as medical appointment reservations and diagnostic records, particularly in a radiology department in a hospital, and can be a part of a hospital information system.
　例えば、被検者の情報を一括管理することで、当該被検者が被曝する放射線量を管理することで、被検者毎に、関心領域の設定時の放射線エネルギーの抑制率を決定する等の調整が可能である。 For example, by determining the radiation energy that the subject is exposed to by managing the information of the subject collectively, the radiation energy suppression rate at the time of setting the region of interest is determined for each subject. Can be adjusted.
　第４の発明は、コンピュータを、前記第１～第６の発明の何れか１つの放射線動画像撮影装置の動画像情報生成手段、制御手段、並びに関心領域設定手段として機能させる放射線動画像撮影制御プログラムである。なお、放射線動画像撮影制御プログラムは記憶媒体に記憶することができる。 A fourth aspect of the present invention is a radiation moving image photographing control that causes a computer to function as moving image information generating means, control means, and region of interest setting means of any one of the first to sixth inventions. It is a program. Note that the radiation moving image capturing control program can be stored in a storage medium.
　以上説明した如く本発明では、関心領域の特定に悪影響を及ぼすことなく、被検者への放射線被曝量を低減することができるという優れた効果を有する。 As described above, the present invention has an excellent effect that the radiation exposure dose to the subject can be reduced without adversely affecting the identification of the region of interest.
本実施の形態に係る放射線情報システムの構成を示すブロック図である。It is a block diagram which shows the structure of the radiation information system which concerns on this Embodiment. 本実施の形態に係る放射線画像撮影システムの放射線撮影室における各装置の配置状態の一例を示す側面図である。It is a side view which shows an example of the arrangement | positioning state of each apparatus in the radiography room of the radiographic imaging system which concerns on this Embodiment. 本実施の形態に係る放射線検出器（一部）の概略構成を示す断面模式図である。It is a cross-sectional schematic diagram which shows schematic structure of the radiation detector (part) based on this Embodiment. 図２に示す放射線画像撮影システムの制御ブロック図である。It is a control block diagram of the radiographic imaging system shown in FIG. 本実施の形態に係る放射線画像撮影システムの撮影制御、並びにＲＯＩ設定のための制御の流れを機能別に示したブロック図である。It is the block diagram which showed the imaging | photography control of the radiographic imaging system concerning this Embodiment, and the flow of control for ROI setting according to the function. 本実施の形態に係る放射線画像撮影準備制御ルーチンを示すフローチャートである。It is a flowchart which shows the radiographic imaging preparation control routine which concerns on this Embodiment. 本実施の形態に係る放射線画像撮影制御ルーチンを示すフローチャートである。It is a flowchart which shows the radiographic imaging control routine which concerns on this Embodiment. 本実施の形態に係るＡＢＣ制御の流れを示すフローチャートである。It is a flowchart which shows the flow of ABC control which concerns on this Embodiment. 本実施の形態に係り、図７のステップ２５２における関心領域設定制御の詳細を示すフローチャートである。It is a flowchart which shows the detail of the region-of-interest setting control in step 252 of FIG. 7 according to the present embodiment. （１）は定常時に電子カセッテで検出する光電変換信号から生成されたＱＬ値のヒストグラム、（２）はＲＯＩ設定時に定常時よりも放射線量を低くした場合での電変換信号から生成されたＱＬ値のヒストグラムである。(1) is a histogram of QL values generated from photoelectric conversion signals detected by an electronic cassette at the time of steady state, and (2) is QLs generated from electric conversion signals when the radiation dose is lower than at the time of steady state at the time of ROI setting. It is a histogram of values. （１）はＲＯＩ設定時に定常時よりも放射線量を低くした場合での電変換信号から生成されたＱＬ値のヒストグラム（図１０（２）と同一）、（２）は図１１（１）におけるダイナミックレンジを圧縮した場合のであるＱＬ値のヒストグラムである。(1) is a histogram of the QL value generated from the electric conversion signal when the radiation dose is lower than in the steady state when setting the ROI (same as FIG. 10 (2)), and (2) is in FIG. 11 (1). It is a histogram of the QL value when the dynamic range is compressed. 放射線動画像撮影工程－放射線被曝量累積値特性曲線を示す特性図である。FIG. 6 is a characteristic diagram showing a radiation moving image photographing process-radiation exposure dose cumulative value characteristic curve. 変形例に係る放射線画像撮影システムの撮影制御、並びにＲＯＩ設定のための制御の流れを機能別に示したブロック図である。It is the block diagram which showed the flow of imaging | photography control of the radiographic imaging system which concerns on a modification, and the control flow for ROI setting according to the function.
　図１は、本実施の形態に係る放射線情報システム（以下、「ＲＩＳ」（Radiology Information System）という。）１０の概略構成図である。このＲＩＳ１０は、静止画に加え、動画像を撮影することが可能である。なお、動画像の定義は、静止画を高速に次々と表示して、動画像として認知させることを言い、静止画を撮影し、電気信号に変換し、伝送して当該電気信号から静止画を再生する、というプロセスの高速に繰り返すものである。従って、前記「高速」の度合いによって、予め定められた時間内に同一領域（一部又は全部）を複数回撮影し、かつ連続的に再生する、所謂「コマ送り」も動画像に包含されるものとする。 FIG. 1 is a schematic configuration diagram of a radiation information system (hereinafter referred to as “RIS” (Radiology Information System)) 10 according to the present embodiment. The RIS 10 can capture a moving image in addition to a still image. The definition of a moving image means that still images are displayed one after another at a high speed and recognized as a moving image.The still image is photographed, converted into an electric signal, transmitted, and the still image is converted from the electric signal. The process of replaying is repeated at high speed. Accordingly, the so-called “frame advance” in which the same area (part or all) is photographed a plurality of times within a predetermined time and continuously reproduced in accordance with the degree of the “high speed” is also included in the moving image. Shall.
　ＲＩＳ１０は、放射線科部門内における、診療予約、診断記録等の情報管理を行うためのシステムであり、病院情報システム（以下、「ＨＩＳ」（Hospital Information System）という。）の一部を構成する。 The RIS 10 is a system for managing information such as medical appointments and diagnosis records in the radiology department, and constitutes a part of a hospital information system (hereinafter referred to as “HIS” (Hospital Information System)).
　ＲＩＳ１０は、複数台の撮影依頼端末装置（以下、「端末装置」という。）１２、ＲＩＳサーバー１４、および病院内の放射線撮影室（あるいは手術室）の個々に設置された複数の放射線画像撮影システム（以下、「撮影システム」という。）１６を有しており、これらが有線や無線のＬＡＮ（Local Area Network）等から成る病院内ネットワーク１８に各々接続されて構成されている。なお、病院内ネットワーク１８には、ＨＩＳ全体を管理するＨＩＳサーバー（図示省略）が接続されている。また、前記放射線画像撮影システム１６は、単一、或いは３以上の設備であってもよく、図１では、撮影室毎に設置しているが、単一の撮影室に２台以上の放射線画像撮影システム１６を配置してもよい。 The RIS 10 includes a plurality of radiographic imaging systems installed individually in a plurality of imaging request terminal devices (hereinafter referred to as “terminal devices”) 12, a RIS server 14, and a radiographic room (or operating room) in a hospital. (Hereinafter referred to as “imaging system”) 16, which are connected to an in-hospital network 18 composed of a wired or wireless LAN (Local Area Network) or the like. The hospital network 18 is connected to an HIS server (not shown) that manages the entire HIS. The radiographic image capturing system 16 may be a single unit or three or more facilities. In FIG. 1, the radiographic image capturing system 16 is installed for each radiographing room. An imaging system 16 may be arranged.
　端末装置１２は、医師や放射線技師が、診断情報や施設予約の入力、閲覧等を行うためのものであり、放射線画像の撮影依頼や撮影予約は、この端末装置１２を介して行われる。各端末装置１２は、表示装置を有するパーソナル・コンピュータを含んで構成され、ＲＩＳサーバー１４と病院内ネットワーク１８を介して相互通信が可能とされている。 The terminal device 12 is used by doctors and radiographers to input and view diagnostic information and facility reservations, and radiographic image capturing requests and imaging reservations are performed via the terminal device 12. Each terminal device 12 includes a personal computer having a display device, and is capable of mutual communication via the RIS server 14 and the hospital network 18.
　一方、ＲＩＳサーバー１４は、各端末装置１２からの撮影依頼を受け付け、撮影システム１６における放射線画像の撮影スケジュールを管理するものであり、データベース１４Ａを含んで構成されている。 On the other hand, the RIS server 14 receives an imaging request from each terminal device 12 and manages a radiographic imaging schedule in the imaging system 16, and includes a database 14A.
　データベース１４Ａは、患者（被検体の属し、「被検者」という場合がある）の属性情報（氏名、性別、生年月日、年齢、血液型、体重、患者ＩＤ（Identification）等）、病歴、受診歴、過去に撮影した放射線画像等の患者に関する情報、撮影システム１６で用いられる、後述する電子カセッテ２０の識別番号（ＩＤ情報）、型式、サイズ、感度、使用開始年月日、使用回数等の電子カセッテ２０に関する情報、および電子カセッテ２０を用いて放射線画像を撮影する環境、すなわち、電子カセッテ２０を使用する環境（一例として、放射線撮影室や手術室等）を示す環境情報を含む。 The database 14A includes attribute information (name, sex, date of birth, age, blood type, weight, patient ID (Identification), etc.), medical history, Medical history, information about the patient such as radiation images taken in the past, identification number (ID information) of the electronic cassette 20 (model information) used in the imaging system 16, model, size, sensitivity, start date of use, number of uses, etc. Information about the electronic cassette 20 and environmental information indicating an environment in which a radiographic image is taken using the electronic cassette 20, that is, an environment in which the electronic cassette 20 is used (for example, a radiographic room or an operating room).
　なお、医療機関が管理する医療関連データをほぼ永久に保管し、必要なときに、必要な場所から瞬時に取り出すシステム（「医療クラウド」等と言う場合がある）を利用して、病院外のサーバーから、患者（被検者）の過去の個人情報等を入手するようにしてもよい。 In addition, medical-related data managed by medical institutions is stored almost permanently, and when necessary, a system (sometimes referred to as a “medical cloud”) that instantly retrieves data from the required location can be used outside the hospital. You may make it acquire the past personal information etc. of a patient (subject) from a server.
　撮影システム１６は、ＲＩＳサーバー１４からの指示に応じて医師や放射線技師の操作により放射線画像の撮影を行う。撮影システム１６は、放射線曝射制御ユニット２２（図４参照）の制御により放射線Ｘを曝射する放射線曝射源２２Ａから、曝射条件に従った線量とされた放射線Ｘを被検者に曝射する放射線発生装置２４と、被検者の撮影対象部位を透過した放射線Ｘを吸収して電荷を発生し、発生した電荷量に基づいて放射線画像を示す画像情報を生成する放射線検出器２６（図３参照）を内蔵する電子カセッテ２０と、電子カセッテ２０に内蔵されているバッテリを充電するクレードル２８と、電子カセッテ２０および放射線発生装置２４を制御するコンソール３０と、を備えている。 The imaging system 16 captures a radiographic image by an operation of a doctor or a radiographer according to an instruction from the RIS server 14. The imaging system 16 exposes the subject to the radiation X having a dose according to the exposure conditions from the radiation exposure source 22A that exposes the radiation X under the control of the radiation exposure control unit 22 (see FIG. 4). A radiation generating device 24 that emits radiation, and a radiation detector 26 that generates radiation by absorbing the radiation X transmitted through the imaging target region of the subject and generates image information indicating a radiation image based on the amount of the generated charge ( 3), a cradle 28 for charging a battery built in the electronic cassette 20, and a console 30 for controlling the electronic cassette 20 and the radiation generator 24.
　コンソール３０は、ＲＩＳサーバー１４からデータベース１４Ａに含まれる各種情報を取得して後述するＨＤＤ８８（図４参照）に記憶し、必要に応じて当該情報を用いて、電子カセッテ２０および放射線発生装置２４の制御を行う。 The console 30 acquires various types of information included in the database 14A from the RIS server 14 and stores them in an HDD 88 (see FIG. 4) described later. If necessary, the console 30 uses the information to store the electronic cassette 20 and the radiation generator 24. Take control.
　図２には、本実施の形態に係る撮影システム１６の放射線撮影室３２における各装置の配置状態の一例が示されている。 FIG. 2 shows an example of the arrangement state of each device in the radiation imaging room 32 of the imaging system 16 according to the present embodiment.
　図２に示される如く、放射線撮影室３２には、立位での放射線撮影を行う際に用いられる立位台３４と、臥位での放射線撮影を行う際に用いられる臥位台３６とが設置されており、立位台３４の前方空間は立位での放射線撮影を行う際の被検者３８の撮影位置とされ、臥位台３６の上方空間は臥位での放射線撮影を行う際の被検者４０の撮影位置とされている。 As shown in FIG. 2, in the radiation imaging room 32, there are a standing table 34 used when performing radiography in a standing position and a prone table 36 used when performing radiation imaging in a lying position. The space in front of the standing table 34 is set as the imaging position of the subject 38 when performing radiography in the standing position, and the upper space of the prone table 36 is used in performing radiography in the prone position. This is the imaging position of the subject 40.
　立位台３４には電子カセッテ２０を保持する保持部４２が設けられており、立位での放射線画像の撮影を行う際には、電子カセッテ２０が保持部４２に保持される。同様に、臥位台３６には電子カセッテ２０を保持する保持部４４が設けられており、臥位での放射線画像の撮影を行う際には、電子カセッテ２０が保持部４４に保持される。 The standing table 34 is provided with a holding unit 42 that holds the electronic cassette 20, and the electronic cassette 20 is held by the holding unit 42 when a radiographic image is taken in the standing position. Similarly, a holding unit 44 that holds the electronic cassette 20 is provided in the lying position table 36, and the electronic cassette 20 is held by the holding unit 44 when a radiographic image is taken in the lying position.
　また、放射線撮影室３２には、単一の放射線曝射源２２Ａからの放射線によって立位での放射線撮影も臥位での放射線撮影も可能とするために、放射線曝射源２２Ａを、水平な軸回り（図２の矢印Ａ方向）に回動可能で、鉛直方向（図２の矢印Ｂ方向）に移動可能で、さらに水平方向（図２の矢印Ｃ方向）に移動可能に支持する支持移動機構４６が設けられている。この図２の矢印Ａ～Ｃ方向へ移動（回動を含む）させる駆動源は、支持移動機構４６に内蔵されており、ここでは、図示を省略する。 Further, in the radiation imaging room 32, the radiation exposure source 22A is installed in a horizontal position in order to enable radiography in the standing position and in the prone position by the radiation from the single radiation exposure source 22A. Support movement that can rotate around the axis (in the direction of arrow A in FIG. 2), move in the vertical direction (in the direction of arrow B in FIG. 2), and further move in the horizontal direction (in the direction of arrow C in FIG. 2). A mechanism 46 is provided. The drive source that moves (including rotation) in the directions of arrows A to C in FIG. 2 is built in the support moving mechanism 46, and is not shown here.
　一方、クレードル２８には、電子カセッテ２０を収納可能な収容部２８Ａが形成されている。 On the other hand, the cradle 28 is formed with an accommodating portion 28A capable of accommodating the electronic cassette 20.
　電子カセッテ２０は、未使用時にはクレードル２８の収容部２８Ａに収納された状態で内蔵されているバッテリに充電が行われ、放射線画像の撮影時には放射線技師等によってクレードル２８から取り出され、撮影姿勢が立位であれば立位台３４の保持部４２に保持され、撮影姿勢が臥位であれば臥位台３６の保持部４４に保持される。 When the electronic cassette 20 is not used, the built-in battery is charged in a state of being accommodated in the accommodating portion 28A of the cradle 28. When a radiographic image is taken, the electronic cassette 20 is taken out of the cradle 28 by a radiographer or the like, and the photographing posture is established. If it is in the upright position, it is held in the holding part 42 of the standing table 34, and if it is in the upright position, it is held in the holding part 44 of the standing table 36.
　ここで、本実施の形態に係る撮影システム１６では、図４に示される如く、放射線発生装置２４とコンソール３０との間、および電子カセッテ２０とコンソール３０との間で、無線通信によって各種情報の送受信を行う（詳細後述）。 Here, in the imaging system 16 according to the present embodiment, as shown in FIG. 4, various kinds of information are transmitted by wireless communication between the radiation generator 24 and the console 30 and between the electronic cassette 20 and the console 30. Send and receive (details will be described later).
　なお、電子カセッテ２０は、立位台３４の保持部４２や臥位台３６の保持部４４で保持された状態のみで使用されるものではなく、その可搬性から、腕部，脚部等を撮影する際には、保持部に保持されていない状態で使用することもできる。 The electronic cassette 20 is not used only in the state of being held by the holding portion 42 of the standing base 34 or the holding portion 44 of the prone position base 36. When photographing, it can be used in a state where it is not held by the holding unit.
　図３は、電子カセッテ２０に装備される放射線検出器２６の３画素部分の構成を概略的に示す断面模式図である。 FIG. 3 is a schematic cross-sectional view schematically showing the configuration of the three pixel portions of the radiation detector 26 provided in the electronic cassette 20.
　図３に示される如く、放射線検出器２６は、絶縁性の基板５０上に、信号出力部５２、センサ部５４（ＴＦＴ基板７４）、およびシンチレータ５６が順次積層しており、信号出力部５２、センサ部５４にはＴＦＴ基板７４の画素群が設けられている。すなわち、複数の画素群は、基板５０上にマトリクス状に配列されており、各画素における信号出力部５２とセンサ部５４とが重なりを有するように構成されている。なお、信号出力部５２とセンサ部５４との間には、絶縁膜５３が介在されている。 As shown in FIG. 3, the radiation detector 26 includes a signal output unit 52, a sensor unit 54 (TFT substrate 74), and a scintillator 56 that are sequentially stacked on an insulating substrate 50. The sensor unit 54 is provided with a pixel group of the TFT substrate 74. That is, the plurality of pixel groups are arranged in a matrix on the substrate 50, and the signal output unit 52 and the sensor unit 54 in each pixel are configured to overlap each other. An insulating film 53 is interposed between the signal output unit 52 and the sensor unit 54.
　シンチレータ５６は、センサ部５４上に透明絶縁膜５８を介して形成されており、上方（基板５０の反対側）または下方から入射してくる放射線を光に変換して発光する蛍光体を成膜したものである。このようなシンチレータ５６を設けることで、被写体を透過した放射線を吸収して発光することになる。 The scintillator 56 is formed on the sensor unit 54 via a transparent insulating film 58, and forms a phosphor that emits light by converting radiation incident from above (opposite side of the substrate 50) or below into light. It is what. Providing such a scintillator 56 absorbs radiation transmitted through the subject and emits light.
　シンチレータ５６が発する光の波長域は、可視光域（波長３６０ｎｍ～８３０ｎｍ）であることが好ましく、この放射線検出器２６によってモノクロ撮像を可能とするためには、緑色の波長域を含んでいることがより好ましい。 The wavelength range of light emitted by the scintillator 56 is preferably in the visible light range (wavelength 360 nm to 830 nm), and in order to enable monochrome imaging by the radiation detector 26, the wavelength range of green is included. Is more preferable.
　シンチレータ５６に用いる蛍光体としては、具体的には、放射線としてＸ線を用いて撮像する場合、ヨウ化セシウム（ＣｓＩ）を含むものが好ましく、Ｘ線曝射時の発光スペクトルが４００ｎｍ～７００ｎｍにあるＣｓＩ（Ｔｌ）（タリウムが添加されたヨウ化セシウム）を用いることが特に好ましい。なお、ＣｓＩ（Ｔｌ）の可視光域における発光ピーク波長は５６５ｎｍである。 Specifically, the phosphor used in the scintillator 56 preferably contains cesium iodide (CsI) when imaging using X-rays as radiation, and has an emission spectrum of 400 nm to 700 nm upon X-ray exposure. It is particularly preferred to use some CsI (Tl) (cesium iodide with thallium added). Note that the emission peak wavelength of CsI (Tl) in the visible light region is 565 nm.
　センサ部５４は、上部電極６０、下部電極６２、および当該上下の電極間に配置された光電変換膜６４を有し、光電変換膜６４は、シンチレータ５６が発する光を吸収して電荷が発生する有機光電変換材料により構成されている。 The sensor unit 54 includes an upper electrode 60, a lower electrode 62, and a photoelectric conversion film 64 disposed between the upper and lower electrodes. The photoelectric conversion film 64 absorbs light emitted from the scintillator 56 and generates electric charges. It is composed of an organic photoelectric conversion material.
　上部電極６０は、シンチレータ５６により生じた光を光電変換膜６４に入射させる必要があるため、少なくともシンチレータ５６の発光波長に対して透明な導電性材料で構成することが好ましく、具体的には、可視光に対する透過率が高く、抵抗値が小さい透明導電性酸化物（ＴＣＯ「Transparent Conductive Oxide」）を用いることが好ましい。なお、上部電極６０としてＡｕなどの金属薄膜を用いることもできるが、透過率を９０％以上得ようとすると抵抗値が増大し易いため、ＴＣＯの方が好ましい。例えば、ＩＴＯ、ＩＺＯ、ＡＺＯ、ＦＴＯ、ＳｎＯ２、ＴｉＯ２、ＺｎＯ２等を好ましく用いることができ、プロセス簡易性、低抵抗性、透明性の観点からはＩＴＯが最も好ましい。なお、上部電極６０は、全画素で共通の一枚構成としてもよく、画素毎に分割してもよい。 Since it is necessary for the upper electrode 60 to cause the light generated by the scintillator 56 to enter the photoelectric conversion film 64, it is preferable that the upper electrode 60 be made of a conductive material that is transparent at least with respect to the emission wavelength of the scintillator 56. It is preferable to use a transparent conductive oxide (TCO “Transparent Conductive Oxide”) having a high transmittance for visible light and a small resistance value. Although a metal thin film such as Au can be used as the upper electrode 60, the TCO is preferable because it tends to increase the resistance when it is desired to obtain a transmittance of 90% or more. For example, ITO, IZO, AZO, FTO, SnO 2 , TiO 2 , ZnO 2 and the like can be preferably used, and ITO is most preferable from the viewpoint of process simplicity, low resistance, and transparency. Note that the upper electrode 60 may have a single configuration common to all pixels, or may be divided for each pixel.
　光電変換膜６４は、有機光電変換材料を含み、シンチレータ５６から発せられた光を吸収し、吸収した光に応じた電荷を発生する。このように有機光電変換材料を含む光電変換膜６４であれば、可視域にシャープな吸収スペクトルを持ち、シンチレータ５６による発光以外の電磁波が光電変換膜６４に吸収されることがほとんどなく、Ｘ線等の放射線が光電変換膜６４で吸収されることによって発生するノイズを効果的に抑制することができる。 The photoelectric conversion film 64 includes an organic photoelectric conversion material, absorbs light emitted from the scintillator 56, and generates electric charge according to the absorbed light. In this way, the photoelectric conversion film 64 including the organic photoelectric conversion material has a sharp absorption spectrum in the visible region, and electromagnetic waves other than light emitted by the scintillator 56 are hardly absorbed by the photoelectric conversion film 64, and X-rays are obtained. The noise generated by the radiation such as being absorbed by the photoelectric conversion film 64 can be effectively suppressed.
　光電変換膜６４を構成する有機光電変換材料は、シンチレータ５６で発光した光を最も効率よく吸収するために、その吸収ピーク波長が、シンチレータ５６の発光ピーク波長と近いほど好ましい。有機光電変換材料の吸収ピーク波長とシンチレータ５６の発光ピーク波長とが一致することが理想的であるが、双方の差が小さければシンチレータ５６から発された光を十分に吸収することが可能である。具体的には、有機光電変換材料の吸収ピーク波長と、シンチレータ５６の放射線に対する発光ピーク波長との差が、１０ｎｍ以内であることが好ましく、５ｎｍ以内であることがより好ましい。 The organic photoelectric conversion material constituting the photoelectric conversion film 64 is preferably such that its absorption peak wavelength is closer to the emission peak wavelength of the scintillator 56 in order to absorb light emitted by the scintillator 56 most efficiently. Ideally, the absorption peak wavelength of the organic photoelectric conversion material matches the emission peak wavelength of the scintillator 56, but if the difference between the two is small, the light emitted from the scintillator 56 can be sufficiently absorbed. . Specifically, the difference between the absorption peak wavelength of the organic photoelectric conversion material and the emission peak wavelength with respect to the radiation of the scintillator 56 is preferably within 10 nm, and more preferably within 5 nm.
　このような条件を満たすことが可能な有機光電変換材料としては、例えばキナクリドン系有機化合物およびフタロシアニン系有機化合物が挙げられる。例えばキナクリドンの可視域における吸収ピーク波長は５６０ｎｍであるため、有機光電変換材料としてキナクリドンを用い、シンチレータ５６の材料としてＣｓＩ（Ｔｌ）を用いれば、上記ピーク波長の差を５ｎｍ以内にすることが可能となり、光電変換膜６４で発生する電荷量をほぼ最大にすることができる。 Examples of the organic photoelectric conversion material that can satisfy such conditions include quinacridone organic compounds and phthalocyanine organic compounds. For example, since the absorption peak wavelength in the visible region of quinacridone is 560 nm, if quinacridone is used as the organic photoelectric conversion material and CsI (Tl) is used as the material of the scintillator 56, the difference in peak wavelength can be made within 5 nm. Thus, the amount of charge generated in the photoelectric conversion film 64 can be substantially maximized.
　各画素を構成するセンサ部５４は、少なくとも下部電極６２、光電変換膜６４、および上部電極６０を含んでいればよいが、暗電流の増加を抑制するため、電子ブロッキング膜６６および正孔ブロッキング膜６８の少なくともいずれかを設けることが好ましく、両方を設けることがより好ましい。 The sensor unit 54 constituting each pixel only needs to include at least the lower electrode 62, the photoelectric conversion film 64, and the upper electrode 60. In order to suppress an increase in dark current, the electron blocking film 66 and the hole blocking film are used. It is preferable to provide at least one of 68, and it is more preferable to provide both.
　電子ブロッキング膜６６は、下部電極６２と光電変換膜６４との間に設けることができ、下部電極６２と上部電極６０間にバイアス電圧を印加したときに、下部電極６２から光電変換膜６４に電子が注入されて暗電流が増加してしまうのを抑制することができる。電子ブロッキング膜６６には、電子供与性有機材料を用いることができる。 The electron blocking film 66 can be provided between the lower electrode 62 and the photoelectric conversion film 64. When a bias voltage is applied between the lower electrode 62 and the upper electrode 60, electrons are transferred from the lower electrode 62 to the photoelectric conversion film 64. It is possible to suppress the dark current from increasing due to the injection of. An electron donating organic material can be used for the electron blocking film 66.
　正孔ブロッキング膜６８は、光電変換膜６４と上部電極６０との間に設けることができ、下部電極６２と上部電極６０間にバイアス電圧を印加したときに、上部電極６０から光電変換膜６４に正孔が注入されて暗電流が増加してしまうのを抑制することができる。正孔ブロッキング膜６８には、電子受容性有機材料を用いることができる。 The hole blocking film 68 can be provided between the photoelectric conversion film 64 and the upper electrode 60. When a bias voltage is applied between the lower electrode 62 and the upper electrode 60, the hole blocking film 68 is transferred from the upper electrode 60 to the photoelectric conversion film 64. It is possible to suppress the increase in dark current due to the injection of holes. An electron-accepting organic material can be used for the hole blocking film 68.
　信号出力部５２は、下部電極６２に対応して、下部電極６２に移動した電荷を蓄積するコンデンサ７０と、コンデンサ７０に蓄積された電荷を電気信号に変換して出力する電界効果型薄膜トランジスタ（Thin Film Transistor、以下、単に薄膜トランジスタという場合がある。）７２が形成されている。コンデンサ７０および薄膜トランジスタ７２の形成された領域は、平面視において下部電極６２と重なる部分を有しており、このような構成とすることで、各画素における信号出力部５２とセンサ部５４とが厚さ方向で重なりを有することとなる。なお、放射線検出器２６（画素）の平面積を最小にするために、コンデンサ７０および薄膜トランジスタ７２の形成された領域が下部電極６２によって完全に覆われていることが望ましい。 The signal output unit 52 corresponds to the lower electrode 62, a capacitor 70 that accumulates the electric charge transferred to the lower electrode 62, and a field effect thin film transistor (Thin) that converts the electric charge accumulated in the capacitor 70 into an electric signal and outputs it. Film-Transistor (hereinafter sometimes simply referred to as a thin film transistor) 72 is formed. The region in which the capacitor 70 and the thin film transistor 72 are formed has a portion that overlaps the lower electrode 62 in plan view. With this configuration, the signal output unit 52 and the sensor unit 54 in each pixel are thick. There will be overlap in the vertical direction. In order to minimize the plane area of the radiation detector 26 (pixel), it is desirable that the region where the capacitor 70 and the thin film transistor 72 are formed is completely covered with the lower electrode 62.
　図４は、本実施の形態に係る撮影システム１６の制御ブロック図である。 FIG. 4 is a control block diagram of the imaging system 16 according to the present embodiment.
　コンソール３０は、サーバー・コンピュータとして機能し、操作メニューや撮影された放射線画像等を表示するディスプレイ８０と、複数のキーを備えると共に、各種の情報や操作指示が入力される操作パネル８２と、を備えている。 The console 30 functions as a server computer, and includes a display 80 for displaying an operation menu, a captured radiographic image, and the like, and an operation panel 82 for inputting various information and operation instructions. I have.
　また、本実施の形態に係るコンソール３０は、装置全体の動作を司るＣＰＵ８４と、制御プログラムを含む各種プログラム等が予め記憶されたＲＯＭ８６と、各種データを一時的に記憶するＲＡＭ８７と、各種データを記憶して保持するＨＤＤ（ハードディスク・ドライブ）８８と、ディスプレイ８０への各種情報の表示を制御するディスプレイドライバ９２と、操作パネル８２に対する操作状態を検出する操作入力検出部９０と、を備えている。 The console 30 according to the present embodiment includes a CPU 84 that controls the operation of the entire apparatus, a ROM 86 that stores various programs including a control program in advance, a RAM 87 that temporarily stores various data, and various data. An HDD (Hard Disk Drive) 88 that stores and holds, a display driver 92 that controls display of various types of information on the display 80, and an operation input detector 90 that detects an operation state of the operation panel 82 are provided. .
　また、コンソール３０は、無線通信により、画像処理装置２３及び放射線発生装置２４との間で後述する曝射条件等の各種情報の送受信を行うと共に、電子カセッテ２０との間で画像データ等の各種情報の送受信を行うＩ／Ｆ（例えば、無線通信部）９６及びＩ／Ｏ９４を備えている。なお、画像処理装置２３は、コンソール３０に含まれる場合がある。 Further, the console 30 transmits and receives various information such as an exposure condition described later between the image processing device 23 and the radiation generation device 24 by wireless communication, and various types of image data and the like with the electronic cassette 20. An I / F (for example, a wireless communication unit) 96 and an I / O 94 that transmit and receive information are provided. Note that the image processing device 23 may be included in the console 30.
　ＣＰＵ８４、ＲＯＭ８６、ＲＡＭ８７、ＨＤＤ８８、ディスプレイドライバ９２、操作入力検出部９０、Ｉ／Ｏ９４、無線通信部９６は、システムバスバスやコントロールバス等のバス９８を介して相互に接続されている。従って、ＣＰＵ８４は、ＲＯＭ８６、ＲＡＭ８７、ＨＤＤ８８へのアクセスを行うことができると共に、ディスプレイドライバ９２を介したディスプレイ８０への各種情報の表示の制御、および無線通信部９６を介した放射線発生装置２４および電子カセッテ２０との各種情報の送受信の制御を各々行うことができる。また、ＣＰＵ８４は、操作入力検出部９０を介して操作パネル８２に対するユーザの操作状態を把握することができる。 The CPU 84, ROM 86, RAM 87, HDD 88, display driver 92, operation input detection unit 90, I / O 94, and wireless communication unit 96 are connected to each other via a bus 98 such as a system bus bus or a control bus. Therefore, the CPU 84 can access the ROM 86, RAM 87, and HDD 88, controls display of various information on the display 80 via the display driver 92, and the radiation generator 24 via the wireless communication unit 96. Control of transmission and reception of various types of information with the electronic cassette 20 can be performed. Further, the CPU 84 can grasp the operation state of the user with respect to the operation panel 82 via the operation input detection unit 90.
　一方、画像処理装置２３は、コンソール３０との間で曝射条件等の各種情報を送受信するＩ／Ｆ（例えば無線通信部）１００と、曝射条件に基づいて、電子カセッテ２０及び放射線発生装置２４を制御する画像処理制御ユニット１０２と、を備えている。また、放射線発生装置２４は、放射線曝射源２２Ａからの放射線曝射を制御する放射線曝射制御ユニット２２を備えている。 On the other hand, the image processing apparatus 23 includes an I / F (for example, a wireless communication unit) 100 that transmits and receives various types of information such as an exposure condition to and from the console 30, and the electronic cassette 20 and the radiation generation apparatus based on the exposure condition. 24, an image processing control unit 102 for controlling 24. The radiation generator 24 includes a radiation exposure control unit 22 that controls radiation exposure from the radiation exposure source 22A.
　画像処理制御ユニット１０２は、システム制御部１０４、パネル制御部１０６、画像処理制御部１０８を備え、相互にバス１１０によって情報をやりとりしている。パネル制御部１０６では、前記電子カセッテ２０からの情報を、無線又は有線により受け付け、画像処理制御部１０８で画像処理が施される。 The image processing control unit 102 includes a system control unit 104, a panel control unit 106, and an image processing control unit 108, and exchanges information with each other via a bus 110. The panel control unit 106 receives information from the electronic cassette 20 wirelessly or by wire, and the image processing control unit 108 performs image processing.
　一方、システム制御部１０４は、コンソール３０から曝射条件として管電圧、管電流等の情報を受信し、受信した曝射条件に基づいて放射線曝射制御ユニット２２の放射線曝射源２２Ａから放射線Ｘを曝射させる制御を行う。 On the other hand, the system control unit 104 receives information such as a tube voltage and a tube current as an exposure condition from the console 30 and, based on the received exposure condition, the radiation X from the radiation exposure source 22A of the radiation exposure control unit 22. Control to expose.
　ところで、放射線画像を撮影するにあたり、全撮影領域の中から、注目するべき領域（関心領域）が抽出（設定）される場合がある。 By the way, in capturing a radiographic image, there are cases where a region to be noticed (region of interest) is extracted (set) from all the imaging regions.
　このため、本実施の形態における、撮影システム１６では、自動的に関心領域を設定する機能を備えており、撮影指示があると、放射線画像撮影準備制御の後、関心領域を設定するための制御が実行されるようになっている。 For this reason, the imaging system 16 in the present embodiment has a function of automatically setting a region of interest. When there is an imaging instruction, control for setting the region of interest after radiographic imaging preparation control is performed. Is to be executed.
　また、本実施の形態の撮影システム１６では、ＡＢＣ「Auto Brightness Control」制御によって、被検者に曝射する放射線の放射線量をフィードバック補正して、適正な画像情報を得ることがなされている。ＡＢＣ制御の原理は、電子カセッテ２０から受信した階調信号に基づいて生成されるＱＬ値の１フレーム分の平均値が、予め定められたしきい値（基準値）に収束するように放射線曝射源２２Ａから曝射される放射線量を調整するものであり、例えば、デジタルカメラやムービーカメラによる光量調整と同様である。 Further, in the imaging system 16 of the present embodiment, appropriate image information is obtained by performing feedback correction on the radiation dose of radiation exposed to the subject by ABC “Auto Brightness Control” control. The principle of ABC control is that radiation exposure is performed so that the average value of one frame of the QL value generated based on the gradation signal received from the electronic cassette 20 converges to a predetermined threshold value (reference value). This is for adjusting the amount of radiation exposed from the radiation source 22A, for example, the same as the light amount adjustment by a digital camera or a movie camera.
　しかしながら、ＡＢＣ制御の撮影初期では、実際に曝射される放射線量と、適正な画像情報を得るための放射線量との間に大きな開きがあると、振幅の激しいフィードバック制御が繰り返され、徐々に収束していく。その分、放射線量を安定させるまでの時間が無駄となり、結果として、ＲＯＩ設定時間が長くなり、放射線の場合、被検者に対して、放射線の被曝量が増加することになる要素となる。 However, at the initial stage of ABC control imaging, if there is a large gap between the radiation dose actually exposed and the radiation dose for obtaining appropriate image information, feedback control with intense amplitude is repeated and gradually Converge. Accordingly, the time until the radiation dose is stabilized is wasted, and as a result, the ROI setting time becomes long, and in the case of radiation, the radiation exposure dose increases for the subject.
　このＲＯＩ設定完了までは所謂本撮影前であり、特に動画像撮影の場合には、ＲＯＩが設定し終えて、ＲＯＩが確定するまでは被検者への放射線被曝量を抑制することが好ましい。 The completion of the ROI setting is before the so-called main imaging, and particularly in the case of moving image shooting, it is preferable to suppress the radiation exposure dose to the subject until the ROI is determined after the ROI has been set.
　そこで、本実施の形態では、撮影指示があった場合に、ＡＢＣ制御を禁止し、かつＲＯＩ設定期間中の放射線量を定常時よりも下げた状態で、ＲＯＩ設定用として、静止画像を撮影（プレ曝射）するようにしている。 Therefore, in the present embodiment, when an imaging instruction is issued, a still image is captured for ROI setting in a state where ABC control is prohibited and the radiation dose during the ROI setting period is lower than that in the normal state ( Pre-exposure).
　図５は、撮影システム１６（主として、コンソール１６、画像処理装置２３、放射線発生装置２４）における、放射線画像撮影（ＲＯＩ設定を含む）のための制御系に特化したブロック図である。なお、このブロック図は、放射線画像撮影制御を機能別に分類したものであり、ハード構成を限定するものではない。従って、それぞれの機能ブロックがコンソール１６、画像処理装置２３、放射線発生装置２４に分散する場合もあり得る。 FIG. 5 is a block diagram specialized in a control system for radiographic image capturing (including ROI setting) in the imaging system 16 (mainly the console 16, the image processing device 23, and the radiation generating device 24). Note that this block diagram categorizes radiographic image capturing control by function, and does not limit the hardware configuration. Therefore, the respective functional blocks may be distributed to the console 16, the image processing device 23, and the radiation generation device 24.
　放射線曝射制御ユニット２２では、放射線量調整部１２０によって調整された放射線量に基づいて、放射線曝射源２２Ａから放射線を曝射する。なお、放射線量調整部１２０は、出力される放射線量（エネルギー）を調整するものであるが、詳細については後述する。 The radiation exposure control unit 22 exposes radiation from the radiation exposure source 22A based on the radiation dose adjusted by the radiation dose adjustment unit 120. The radiation dose adjustment unit 120 adjusts the output radiation dose (energy), and details will be described later.
　放射線曝射源２２Ａから曝射された放射線は、臥位台３６に横たわっている被検者４０を通過して電子カセッテ２０の放射線検出器２６（図３参照）へ至るようになっている。放射線検出器２６では、蛍光体膜５６（図３参照）によって放射線量に応じた光量の光が発光し、ＴＦＴ基板７４によって光電変換される。 The radiation exposed from the radiation exposure source 22A passes through the subject 40 lying on the prone position table 36 and reaches the radiation detector 26 (see FIG. 3) of the electronic cassette 20. In the radiation detector 26, the phosphor film 56 (see FIG. 3) emits light having a light amount corresponding to the radiation amount and is photoelectrically converted by the TFT substrate 74.
　電子カセッテ２０のＴＦＴ基板７４は、信号取得部１２２に接続されている。信号取得部１２２では、放射線曝射源２２Ａから曝射された放射に基づいて光電変換された信号を取得し、階調信号解析部１２４へ送出する。なお、この光電変換信号は、アナログ信号であってもよいし、電子カセッテ２０内の制御部において、デジタル信号に変換した後でもよい。 The TFT substrate 74 of the electronic cassette 20 is connected to the signal acquisition unit 122. The signal acquisition unit 122 acquires a signal photoelectrically converted based on the radiation exposed from the radiation exposure source 22 </ b> A and sends it to the gradation signal analysis unit 124. The photoelectric conversion signal may be an analog signal or may be converted into a digital signal by the control unit in the electronic cassette 20.
　階調信号解析部１２４には、ダイナミックレンジ調整部１２６が接続されている。 A dynamic range adjustment unit 126 is connected to the gradation signal analysis unit 124.
　階調信号解析部１２４では、前記ダイナミックレンジ調整部１２６から受けたダイナミックレンジの圧縮パラメータ（以下、「圧縮率」といい、定常時は、圧縮率ＤＲNである。）に基づいて、光電変換信号のヒストグラム解析を行う。この結果、例えば、図１０（１）に示される如く、階調（濃度）毎のデータカウント数（階調信号）を得る。この階調信号をＱＬ値という場合がある。なお、ここでは、ＱＬ値を階調信号そのもの（生データ）とするが、階調信号そのものではなく、例えば、電子カセッテ２０のコンデンサ７０（図３参照）や、その他回路系の静電容量に起因するノイズ分を補正した後の値をＱＬ値としてもよい。 In the gradation signal analysis unit 124, based on the dynamic range compression parameter received from the dynamic range adjustment unit 126 (hereinafter referred to as "compression rate", the compression rate DRN in the normal state), the photoelectric conversion signal. Histogram analysis is performed. As a result, for example, as shown in FIG. 10A, a data count number (gradation signal) for each gradation (density) is obtained. This gradation signal may be referred to as a QL value. Here, although the QL value is the gradation signal itself (raw data), it is not the gradation signal itself, but, for example, the capacitor 70 (see FIG. 3) of the electronic cassette 20 or other circuit system capacitance. A value after correcting the noise component may be used as the QL value.
　階調信号解析部１２４は、目的別静止画像生成指示部１２５に接続されている。階調信号解析部１２４では、１フレーム分の階調信号が揃った時点で、目的別静止画像生成指示部１２５を介して、静止画像生成部１２８へ送出する。 The gradation signal analysis unit 124 is connected to the purpose-specific still image generation instruction unit 125. In the gradation signal analysis unit 124, when the gradation signals for one frame have been prepared, the gradation signal analysis unit 124 sends them to the still image generation unit 128 via the purpose-specific still image generation instruction unit 125.
　この目的別静止画像生成指示部１２５では、ＲＯＩ設定のための静止画像の生成であるのか、動画像を生成する基となる静止画像の生成であるかを判別し、何れかの指示信号を静止画像生成部１２８へ送出する。すなわち、目的別静止画像生成指示部１２５では、後述する関心領域設定部１３８からＲＯＩ設定の開始信号又は完了信号を受けるようになっている。開始信号を受けると、ＲＯＩ設定用の静止画像を生成するように静止画像生成部１２８へ指示する。一方、完了信号を受けると動画像編集用の静止画像を生成するように静止画像生成部１２８へ指示する。 The purpose-specific still image generation instruction unit 125 determines whether it is generation of a still image for ROI setting or generation of a still image that is a basis for generating a moving image, and either instruction signal is stopped. The image is sent to the image generation unit 128. That is, the purpose-specific still image generation instruction unit 125 receives a ROI setting start signal or completion signal from a region-of-interest setting unit 138 described later. When the start signal is received, the still image generation unit 128 is instructed to generate a ROI setting still image. On the other hand, when the completion signal is received, the still image generation unit 128 is instructed to generate a still image for moving image editing.
　この違いは、例えば、撮影した領域の広狭等が考えられる。すなわち、静止画像生成部１２８では、ＲＯＩ設定の場合は、撮影した全領域の階調信号に基づいて静止画像が生成され、動画像編集の場合は、設定されたＲＯＩの領域内（或いは、ＲＯＩ領域内の周囲の一部を含む）の階調信号に基づいて静止画像が生成される。 This difference may be, for example, the breadth of the captured area. In other words, the still image generation unit 128 generates a still image based on the gradation signals of the entire captured region in the case of ROI setting, and in the region of the set ROI (or in the ROI in the case of moving image editing). A still image is generated based on the gradation signal (including a part of the periphery in the region).
　静止画像生成部１２８では、受け付けた階調信号に基づいて、１フレーム毎の画像データを生成する。 The still image generation unit 128 generates image data for each frame based on the received gradation signal.
　ここで、動画像編集用の静止画像と、ＲＯＩ設定用の静止画撮影の場合とでは、電子カセッテ２０から送られる光電変換信号そのものが異なり、例えば、本実施の形態のように、動画像編集の場合には、転送速度を優先するため、ビニング処理がなされる場合がある。 Here, the still image for moving image editing and the still image shooting for ROI setting differ in the photoelectric conversion signal itself sent from the electronic cassette 20, for example, as in this embodiment, the moving image editing In this case, a binning process may be performed to give priority to the transfer rate.
　一方、ＲＯＩ設定用の静止画像を生成する場合には、画質を優先するため、ＴＦＴ基板７４における最大の画素数に基づく画像データが生成される。 On the other hand, when generating a still image for ROI setting, image data based on the maximum number of pixels on the TFT substrate 74 is generated in order to prioritize image quality.
　静止画像生成部１２８は、動画像編集部１３０及び関心領域設定部１３８に接続されている。動画像編集部１３０では、前記静止画像生成部１２８から逐次送出される１フレーム毎の画像データを組み合わせて、動画像を編集する。編集された動画像は、ディスプレイドライバ９２を介して、ディスプレイ８０に表示されるようになっている。なお、前記静止画像生成部１２８は、ディスプレイドライバ９２に接続されており、静止画像をディスプレイ８０に表示することも可能となっている。 The still image generating unit 128 is connected to the moving image editing unit 130 and the region of interest setting unit 138. The moving image editing unit 130 combines the image data for each frame sequentially transmitted from the still image generating unit 128 to edit the moving image. The edited moving image is displayed on the display 80 via the display driver 92. The still image generation unit 128 is connected to the display driver 92, and can display a still image on the display 80.
　動画像編集部１３０は、平均ＱＬ値演算部１３２に接続されている。この平均ＱＬ値演算部１３２では、動画像の各フレーム（或いは、適宜抜き取った１フレーム）のＱＬ値の平均値を演算する。平均ＱＬ値演算部１３２での演算結果は、ＡＢＣ制御部１３４へ送出されるようになっている。 The moving image editing unit 130 is connected to the average QL value calculation unit 132. The average QL value calculation unit 132 calculates the average value of the QL values of each frame (or one frame appropriately extracted) of the moving image. The calculation result in the average QL value calculation unit 132 is sent to the ABC control unit 134.
　ＡＢＣ制御部１３４には、基準ＱＬ値メモリ１３６が接続されている。ＡＢＣ制御部１３４では、前記平均ＱＬ値演算部１３２から受け付けたＱＬ平均値と、基準ＱＬ値メモリ１３６から受け付けた基準ＱＬ値とを比較して、ＱＬ平均値が基準ＱＬ値に収束するための補正情報ΔＸを生成する。この補正情報ΔＸは、放射線曝射源２２Ａから曝射される放射線量（エネルギー）を増減するための補正係数として適用される。 A reference QL value memory 136 is connected to the ABC control unit 134. The ABC control unit 134 compares the QL average value received from the average QL value calculation unit 132 with the reference QL value received from the reference QL value memory 136, and converges the QL average value to the reference QL value. Correction information ΔX is generated. This correction information ΔX is applied as a correction coefficient for increasing or decreasing the radiation dose (energy) exposed from the radiation exposure source 22A.
　ＡＢＣ制御部１３４で生成された補正情報ΔＸは、前記放射線量調整部１２０へ送出される。放射線量調整部１２０では、放射線量ＸＮが増減される（ＸＮ←ＸＮ×ΔＸ）。放射線量調整部１２０は、放射線量ＸＮの初期値を記憶しており、曝射指示があった時点は当該初期値から曝射が開始される。これにより、動画像として生成される基となる光電変換信号を、階調信号を得るための過不足のない適正な範囲内に収めることができる。これは、光電変換信号と画像濃度との相関関係を示す特性図の変化率が大きい領域（例えば、感光材料で言えば、γ曲線の中間領域）であることを意味する。 The correction information ΔX generated by the ABC control unit 134 is sent to the radiation dose adjustment unit 120. In the radiation dose adjustment unit 120, the radiation dose XN is increased or decreased (XN ← XN × ΔX). The radiation dose adjustment unit 120 stores an initial value of the radiation dose XN, and when the exposure instruction is given, the exposure is started from the initial value. As a result, the photoelectric conversion signal that is the basis for generating the moving image can be within an appropriate range without excess or deficiency for obtaining the gradation signal. This means that it is a region where the rate of change in the characteristic diagram showing the correlation between the photoelectric conversion signal and the image density is large (for example, an intermediate region of the γ curve in the case of a photosensitive material).
　なお、本実施の形態では、放射線量ＸＮの補正の際、補正情報ΔＸを乗（除）算の係数としたが、加（減）算係数（ＸＮ←ＸＮ＋ΔＸＮ）としてもよい。 In the present embodiment, the correction information ΔX is used as a multiplication (division) coefficient when correcting the radiation dose XN, but an addition (subtraction) coefficient (XN ← XN + ΔXN) may be used.
　ここで、前述したように、本実施の形態では、ＲＯＩを設定する必要がある。このため、前記関心領域設定部１３８では、静止画像生成部１２８から受け付けたＲＯＩ設定用の静止画像データに基づいて、関心領域（ＲＯＩ）を設定する。ＲＯＩの設定として、一般的な方法は、ある値以上の画素値をもつ画素を囲う方法であり、放射能が集積した臓器や病変全体を囲うのに適している。また、別の方法は、標準となる画像に、予めＲＯＩを定義しておきそれを対象画像に合わせこむ方法等がある。さらには、動画像の場合には、変化量の大きい箇所を抽出するようにしてもよい。 Here, as described above, in this embodiment, it is necessary to set the ROI. Therefore, the region of interest setting unit 138 sets a region of interest (ROI) based on the ROI setting still image data received from the still image generating unit 128. As a method of setting ROI, a general method is a method of surrounding pixels having a pixel value equal to or greater than a certain value, and is suitable for surrounding an organ or a lesion where radioactivity is accumulated. As another method, there is a method in which an ROI is defined in advance in a standard image and is matched with a target image. Furthermore, in the case of a moving image, a portion with a large change amount may be extracted.
　関心領域設定部１３８では、ＲＯＩを設定する際に、前記目的別静止画像生成指示部１２５及びＲＯＩ確定前曝射制御部１４０に対して、少なくともＲＯＩの設定開始時を示す開始信号、並びに設定完了時を示す完了信号を出力するようになっている。目的別静止画像生成指示部１２５では、前述したように、この開始信号又は完了信号によって、静止画像の目的を認識する。 In setting the ROI, the region-of-interest setting unit 138 sets at least a start signal indicating the start of setting of the ROI and the setting completion to the still image generation instruction unit 125 for each purpose and the exposure control unit 140 before ROI determination A completion signal indicating the time is output. As described above, the purpose-specific still image generation instruction unit 125 recognizes the purpose of the still image based on the start signal or the completion signal.
　ＲＯＩ確定前曝射制御部１４０は、前記放射線量調整部１２０、前記ＡＢＣ制御部１３４、前記ダイナミックレンジ調整部１２６にそれぞれ接続されている。 The pre-ROI determination exposure control unit 140 is connected to the radiation dose adjustment unit 120, the ABC control unit 134, and the dynamic range adjustment unit 126, respectively.
　ＲＯＩ確定前曝射制御部１４０からＡＢＣ制御部１３４へは、ＲＯＩ設定中は、ＡＢＣ制御を禁止することを指示する制御禁止信号を出力する。 During the ROI setting, the control prohibition signal for instructing prohibition of the ABC control is output from the pre-ROI determination exposure control unit 140 to the ABC control unit 134.
　また、ＲＯＩ確定前曝射制御部１４０から放射線量調整部１２０へは、前記初期値として記憶されている放射線量ＸＮよりも低い放射線量（最小エネルギー）ＸROIに調整するための信号である最小エネルギー指示信号を出力する（ＸROI＜ＸN）。 Further, the minimum energy which is a signal for adjusting the radiation dose (minimum energy) XROI lower than the radiation dose XN stored as the initial value from the pre-ROI determination exposure control unit 140 to the radiation dose adjustment unit 120. An instruction signal is output (XROI <XN).
　この結果、図１０（２）及び図１１（１）に示される如く、調信号解析部１２４における、光電変換信号のヒストグラム解析の結果は、設定されたダイナミックレンジの一部（ＱＬ値の低い領域）しか対象とならない。 As a result, as shown in FIGS. 10 (2) and 11 (1), the result of the histogram analysis of the photoelectric conversion signal in the modulation signal analysis unit 124 is a part of the set dynamic range (region with a low QL value). ) Only.
　そこで、ＲＯＩ確定前曝射制御部１４０からダイナミックレンジ調整部１２６へは、ＲＯＩ設定中は、ダイナミックレンジの圧縮率を、定常時の圧縮率ＤＲNから、当該圧縮率ＤＲNよりも圧縮率が高いＲＯＩ設定時用の圧縮率ＤＲROIとするための指示であるダイナミックレンジ圧縮率指示信号を出力する（ＤＲROI＞ＤＲN）。 Therefore, from the pre-ROI determination exposure control unit 140 to the dynamic range adjustment unit 126, during the ROI setting, the compression rate of the dynamic range is the ROI whose compression rate is higher than the compression rate DRN from the compression rate DRN at the steady state. A dynamic range compression ratio instruction signal that is an instruction for setting the compression ratio DRROI for setting is output (DRROI> DRN).
　この結果、図１１（２）に示される如く、光電変換信号のヒストグラム解析の結果が、ダイナミックレンジの全域が対象となる。 As a result, as shown in FIG. 11B, the result of the histogram analysis of the photoelectric conversion signal covers the entire dynamic range.
　すなわち、本実施の形態では、ＲＯＩ設定中は、放射線曝射源２２Ａから曝射する放射線量（エネルギー）を低くし（放射線量ＸNから放射線量ＸROIへ）、かつ、低くした分、ダイナミックレンジの圧縮率を高くすることで（圧縮率ＤＲNからＤＲROIへ）、放射線量低下による被検者の被曝量軽減と、高精度のＲＯＩ設定とを両立することが可能となる。 That is, in the present embodiment, during the ROI setting, the radiation dose (energy) exposed from the radiation exposure source 22A is lowered (from the radiation dose XN to the radiation dose XROI), and the amount of the dynamic range is reduced. By increasing the compression rate (from the compression rate DRN to DRROI), it becomes possible to achieve both reduction in the exposure dose of the subject due to a decrease in radiation dose and high-precision ROI setting.
　なお、関心領域設定部１３０におけるＲＯＩの設定が完了すると、完了信号が目的別静止画像生成指示部１２５及びＲＯＩ確定前曝射制御部１４０へ送出されることで、撮影される静止画像が動画像編集用であることが認識されると共に、放射線量調整部１２０では、放射線量が初期値ＸNに設定され、ダイナミックレンジ調整部１２６では、圧縮率がＤＲNに設定される。また、ＡＢＣ制御部１３４によるＡＢＣ制御も実行可能となる。 When the ROI setting in the region-of-interest setting unit 130 is completed, a completion signal is sent to the still image generation instruction unit 125 for each purpose and the exposure control unit 140 before ROI determination, so that the captured still image is a moving image. While being recognized for editing, the radiation dose adjustment unit 120 sets the radiation dose to the initial value XN, and the dynamic range adjustment unit 126 sets the compression rate to DRN. Also, ABC control by the ABC control unit 134 can be executed.
　以下に、本実施の形態の作用を図６～図９のフローチャートに従い説明する。 Hereinafter, the operation of the present embodiment will be described with reference to the flowcharts of FIGS.
　図６は、放射線画像撮影準備制御ルーチンを示すフローチャートである。 FIG. 6 is a flowchart showing the radiographic imaging preparation control routine.
　ステップ２００では、撮影指示があったか否かが判断され、否定判定されるとこのルーチンは終了し、肯定判定されるとステップ２０２へ移行する。 In step 200, it is determined whether or not a shooting instruction has been issued. If a negative determination is made, this routine ends. If an affirmative determination is made, the routine proceeds to step 202.
　ステップ２０２では、初期情報入力画面が表示される。すなわち、予め定められた初期情報入力画面をディスプレイ８０により表示させるようにディスプレイドライバ９２を制御し、ステップ２０４へ移行する。ステップ２０４では、所定情報の入力待ちを行う。 In step 202, an initial information input screen is displayed. That is, the display driver 92 is controlled to display a predetermined initial information input screen on the display 80, and the process proceeds to step 204. In step 204, input of predetermined information is waited.
　初期情報入力画面では、これから放射線画像の撮影を行う被検者の氏名、撮影対象部位、撮影時の姿勢、および撮影時の放射線Ｘの曝射条件（本実施の形態では、放射線Ｘを曝射する際の管電圧および管電流）の入力を促すメッセージと、これらの情報の入力領域が表示される。 In the initial information input screen, the name of the subject who will take a radiographic image, the part to be imaged, the posture at the time of radiography, and the exposure condition of the radiographic X at the time of radiography (in this embodiment, the radiation X is exposed Message for prompting the input of the tube voltage and tube current) and an input area for such information are displayed.
　初期情報入力画面がディスプレイ８０に表示されると、撮影者は、撮影対象とする被検者の氏名、撮影対象部位、撮影時の姿勢、および曝射条件を、各々対応する入力領域に操作パネル８２を介して入力する。 When the initial information input screen is displayed on the display 80, the photographer displays the name of the subject to be imaged, the region to be imaged, the posture at the time of imaging, and the exposure conditions in the corresponding input areas. Input via 82.
　撮影者は、被検者と共に放射線撮影室３２に入室し、例えば、臥位である場合は、対応する臥位台３６の保持部４４に電子カセッテ２０を保持させると共に放射線曝射源２２Ａを対応する位置に位置決めした後、被検者を所定の撮影位置に位置（ポジショニング）させる。なお、撮影対象部位が腕部、脚部等の電子カセッテ２０を保持部に保持させない状態で放射線画像の撮影を行う場合は、当該撮影対象部位を撮影可能な状態に被検者、電子カセッテ２０、および放射線曝射源２２Ａを位置決め（ポジショニング）させる。 The radiographer enters the radiography room 32 together with the subject. For example, when the radiographer is in the supine position, the radio cassette 20A is supported while the electronic cassette 20 is held in the holding unit 44 of the corresponding prone position table 36. After positioning at the position to be performed, the subject is positioned (positioned) at a predetermined imaging position. In addition, when radiography is performed in a state where the imaging target site does not hold the electronic cassette 20 such as an arm or a leg on the holding unit, the subject and the electronic cassette 20 are ready to capture the imaging target site. , And the radiation exposure source 22A is positioned (positioned).
　その後、撮影者は、放射線撮影室３２を退室し、例えば、初期情報入力画面の下端近傍に表示されている終了ボタンを、操作パネル８２を介して指定する。撮影者によって終了ボタンが指定されると、前記ステップ２０４が肯定判定となって、ステップ２０６に移行する。なお、図６のフローチャートでは、ステップ２０４の否定判定を無限ループとしたが、操作パネル８２上に設けたキャンセルボタンの操作によって、強制終了させるようにしてもよい。 Thereafter, the radiographer leaves the radiation imaging room 32 and designates, for example, an end button displayed near the lower end of the initial information input screen via the operation panel 82. When an end button is designated by the photographer, step 204 is affirmative and the process proceeds to step 206. In the flowchart of FIG. 6, the negative determination in step 204 is an infinite loop, but it may be forcibly terminated by operating a cancel button provided on the operation panel 82.
　ステップ２０６では、上記初期情報入力画面において入力された情報（以下、「初期情報」という。）を電子カセッテ２０に無線通信部９６を介して送信した後、次のステップ２０８へ移行して、前記初期情報に含まれる曝射条件を放射線発生装置２４へ無線通信部９６を介して送信することにより当該曝射条件を設定する。これに応じて放射線発生装置２４の画像処理制御ユニット１０２は、受信した曝射条件での曝射準備を行う。 In step 206, information input on the initial information input screen (hereinafter referred to as “initial information”) is transmitted to the electronic cassette 20 via the wireless communication unit 96, and then the process proceeds to the next step 208. The exposure condition is set by transmitting the exposure condition included in the initial information to the radiation generator 24 via the wireless communication unit 96. In response to this, the image processing control unit 102 of the radiation generator 24 prepares for exposure under the received exposure conditions.
　次のステップ２１０では、ＡＢＣ制御の起動を指示し、次いで、ステップ２１２へ移行して、放射線の曝射開始を指示する指示情報を放射線発生装置２４へ無線通信部９６を介して送信し、このルーチンは終了する。なお、このステップ２１０のＡＢＣ制御の詳細については、図８のフローチャートを用い、後述する。 In the next step 210, the start of the ABC control is instructed, and then the process proceeds to step 212, where the instruction information instructing the start of radiation exposure is transmitted to the radiation generator 24 via the wireless communication unit 96. The routine ends. The details of the ABC control in step 210 will be described later using the flowchart of FIG.
　次に、図７のフローチャートに従い、放射線画像撮影制御の流れを説明する。 Next, the flow of radiographic image capturing control will be described with reference to the flowchart of FIG.
　ステップ２５０では、曝射開始指示があった否かが判断され、否定判定された場合はこのルーチンは終了し、肯定判定された場合はステップ２５２へ移行する。 In step 250, it is determined whether or not an exposure start instruction has been issued. If a negative determination is made, this routine ends. If an affirmative determination is made, the routine proceeds to step 252.
　ステップ２５２では、関心領域設定制御が実行され、当該関心領域設定が終了すると、ステップ２５４へ移行する。なお、このステップ２５２の関心領域設定制御の詳細については、図９のフローチャートを用い、後述する。 In step 252, the region-of-interest setting control is executed, and when the region-of-interest setting ends, the process proceeds to step 254. Details of the region-of-interest setting control in step 252 will be described later using the flowchart of FIG.
　図７に示される如く、ステップ２５４では、定常時放射線量（初期値）ＸNを読み出し、次いでステップ２５６へ移行して、放射線曝射制御ユニット２２は、放射線発生装置２４がコンソール３０から受信した曝射条件に応じた管電圧および管電流での放射線Ｘの放射線曝射源２２Ａからの射出を開始する。放射線曝射源２２Ａから射出された放射線Ｘは、被検者を透過した後に電子カセッテ２０に到達する。 As shown in FIG. 7, in step 254, the steady-state radiation dose (initial value) XN is read, and then the process proceeds to step 256 where the radiation exposure control unit 22 performs the exposure received by the radiation generator 24 from the console 30. The emission of the radiation X from the radiation exposure source 22A with the tube voltage and the tube current according to the irradiation conditions is started. The radiation X emitted from the radiation exposure source 22A reaches the electronic cassette 20 after passing through the subject.
　次のステップ２５８では、現在格納されている放射線量補正情報を読み出す。この放射線量補正情報は、ＡＢＣ制御によって生成されるものであり、補正係数ΔＸとして格納されている。 In the next step 258, the currently stored radiation dose correction information is read out. This radiation dose correction information is generated by ABC control and is stored as a correction coefficient ΔX.
　次のステップ２６０では、ＡＢＣ制御に基づく補正処理が実行される。すなわち、電子カセッテ２０から得た階調信号（ＱＬ値）に基づいて、関心領域画像のＱＬ値の平均値を演算し、このＱＬ値の平均値が予め定めたしきい値と比較され、しきい値に収束するように、放射線量にフィードバック制御される。 In the next step 260, correction processing based on ABC control is executed. That is, based on the gradation signal (QL value) obtained from the electronic cassette 20, an average value of the QL values of the region of interest image is calculated, and the average value of the QL values is compared with a predetermined threshold value. The radiation dose is feedback controlled so as to converge to the threshold value.
　次のステップ２６２では、動画像編集処理が実行されて、当該編集された動画像は、ステップ２６４において、ディスプレイ８０に表示される（画像表示処理）。 In the next step 262, the moving image editing process is executed, and the edited moving image is displayed on the display 80 in step 264 (image display process).
　次のステップ２６６では、画像データ（動画像データ）をＲＩＳサーバー１４（図１参照）へ病院内ネットワーク１８を介して送信し、ステップ２６８へ移行する。ステップ２６８では、撮影終了の指示があったか否かが判断され、肯定判定されると、ステップ２７０で曝射を終了し、放射線画像撮影制御プログラムを終了する。なお、ＲＩＳサーバー１４へ送信された補正画像データはデータベース１４Ａに格納され、医師が撮影された放射線画像の読影や診断等を行うことが可能となる。 In the next step 266, image data (moving image data) is transmitted to the RIS server 14 (see FIG. 1) via the in-hospital network 18, and the process proceeds to step 268. In step 268, it is determined whether or not an instruction to end imaging is given. If an affirmative determination is made, exposure is terminated in step 270, and the radiographic image capturing control program is terminated. The corrected image data transmitted to the RIS server 14 is stored in the database 14A, so that a doctor can perform radiogram image interpretation and diagnosis.
　次に、図８に従い図６のステップ２１０で指示されて起動するＡＢＣ制御の流れを説明する。なお、この図８のＡＢＣ制御ルーチンは、前記図６及び図７のフローチャートとは独立して実行されるようにしてもよい。 Next, the flow of ABC control that is instructed and started in step 210 of FIG. 6 will be described with reference to FIG. Note that the ABC control routine of FIG. 8 may be executed independently of the flowcharts of FIGS.
　ステップ３００では、ＲＯＩ確定後の曝射制御中か否かが判断される。なお、これは、後述する図９のステップ３２０のＡＢＣ制御禁止指示、ステップ３３８のＡＢＣ制御禁止解除指示に基づいて判断される。 In step 300, it is determined whether or not the exposure control after the ROI is determined. This is determined based on an ABC control prohibition instruction in Step 320 and an ABC control prohibition release instruction in Step 338, which will be described later.
　ステップ３００で否定判定された場合は、ＲＯＩ設定中であると判断し、このルーチンは終了する。すなわち、ＡＢＣ制御は実行されない。 If a negative determination is made in step 300, it is determined that ROI is being set, and this routine ends. That is, ABC control is not executed.
　また、ステップ３００で肯定判定されると、ステップ３０２へ移行してダイナミックレンジ圧縮率を定常時の圧縮率ＤＲNに設定し、次いで、ステップ３０４へ移行して画像データを取り込み、ステップ３０６へ移行する。 If the determination in step 300 is affirmative, the process proceeds to step 302 to set the dynamic range compression ratio to the compression ratio DRN at the normal time, and then the process proceeds to step 304 to capture image data, and the process proceeds to step 306. .
　ステップ３０６では、取り込んだ画像データから平均ＱＬ値を演算し、次いでステップ３０８へ移行して基準ＱＬ値を読み出す。 In step 306, the average QL value is calculated from the captured image data, and then the process proceeds to step 308 to read the reference QL value.
　次のステップ３１０では、取り込んだ画像データから平均ＱＬ値と、読み出した基準ＱＬ値とを比較し、補正の可否を判定してステップ３１２へ移行する。例えば、補正の可否の判定は、比較の結果において、差が所定以上の場合は予め定めた量の補正を行い当該差が所定未満であれば補正しないといった所謂オン／オフ判定であってもよいし、前記差に基づいて、予め定めた演算式（例えば、ＰＩＤ制御等に基づく演算式）による演算の解であってもよい。 In the next step 310, the average QL value from the captured image data is compared with the read reference QL value to determine whether correction is possible, and the process proceeds to step 312. For example, the determination as to whether correction is possible may be a so-called on / off determination in which a predetermined amount of correction is performed if the difference is greater than or equal to a predetermined value and no correction is made if the difference is less than a predetermined value. And based on the said difference, the solution of the calculation by a predetermined arithmetic expression (for example, arithmetic expression based on PID control etc.) may be sufficient.
　ステップ３１２では、ステップ３１０での比較、判定結果に基づいて、放射線量ＸROIの補正情報ΔＸを生成し、次いで、ステップ３１４へ移行して、ステップ３１２で生成した補正情報ΔＸを格納し、このルーチンは終了する。 In step 312, correction information ΔX of the radiation dose XROI is generated based on the comparison and determination results in step 310, and then the process proceeds to step 314 to store the correction information ΔX generated in step 312. Ends.
　図９は、前記図７のステップ２５２において実行される関心領域設定制御ルーチンを示すフローチャートである。この関心領域設定制御ルーチンの実行が開始されると、ＲＯＩ確定前曝射制御部２４０に対して開始信号を出力する。 FIG. 9 is a flowchart showing a region-of-interest setting control routine executed in step 252 of FIG. When execution of this region-of-interest setting control routine is started, a start signal is output to the exposure control unit 240 before ROI determination.
　ステップ３２０では、まず、ＡＢＣ制御の禁止を指示する。これにより、放射線曝射源２２Ａから曝射される放射線量はフィードバック制御されず、一定となる。 In step 320, first, prohibition of ABC control is instructed. As a result, the radiation dose exposed from the radiation exposure source 22A is constant without feedback control.
　次のステップ３２２では、関心領域設定時放射線量ＸROIを読み出す。この関心領域設定時放射線量ＸROIは、定常時放射線量Nよりも低い放射線量である（ＸROI＜ＸN）。 In the next step 322, the radiation dose XROI at the time of region of interest setting is read. This region-of-interest setting radiation dose XROI is lower than the steady-state radiation dose N (XROI <XN).
　次のステップ３２４では、関心領域設定時ダイナミックレンジ圧縮率ＤＲROIを読み出す。この関心領域設定時ダイナミックレンジ圧縮率ＤＲROIは、所定のダイナミックレンジ圧縮率ＤＲN（以下、「定常時ダイナミックレンジＤＲN」という）よりも高い圧縮率である（ＤＲROI＞ＤＲN）。 In the next step 324, the dynamic range compression ratio DRROI is read when the region of interest is set. This region-of-interest setting dynamic range compression rate DRROI is a compression rate higher than a predetermined dynamic range compression rate DRN (hereinafter referred to as “steady-state dynamic range DRN”) (DRROI> DRN).
　次のステップ３２６では、前記放射線量ＸROIでプレ曝射を開始し、ステップ３２８へ移行する。ステップ３２８では、ステップ３２６のプレ曝射による撮影データ（階調信号）に基づいて、ＲＯＩ設定用の静止画像を生成し、ステップ３３０へ移行する。ステップ３３０では、ＲＯＩ設定開始を指示して、ステップ３３２へ移行する。ステップ３２６でのプレ曝射は、静止画像のための曝射であるため、当該プレ曝射中の僅かな時間以外は、放射線量ＸROIが累積されることがない In the next step 326, pre-exposure is started with the radiation dose XROI, and the process proceeds to step 328. In step 328, a still image for ROI setting is generated based on the photographing data (gradation signal) obtained by the pre-exposure in step 326, and the process proceeds to step 330. In step 330, the start of ROI setting is instructed, and the process proceeds to step 332. Since the pre-exposure in step 326 is an exposure for a still image, the radiation dose XROI is not accumulated except for a short time during the pre-exposure.
　次のステップ３３２では、画像表示処理を実行し、ステップ３３４へ移行する。 In the next step 332, image display processing is executed, and the process proceeds to step 334.
　ステップ３３４では、動画像から関心領域を設定できたか否かが判断され、否定判定された場合は、ステップ３３２へ戻り、画像表示を継続する。また、ステップ３３４で肯定判定された場合は、ＲＯＩ設定が完了したと判断し、ステップ３３８へ移行して、ＡＢＣ制御の禁止を解除してこのルーチンは終了する。 In step 334, it is determined whether or not the region of interest can be set from the moving image. If a negative determination is made, the process returns to step 332 and the image display is continued. If the determination in step 334 is affirmative, it is determined that the ROI setting has been completed, the process proceeds to step 338, the prohibition of ABC control is canceled, and this routine ends.
　この、ＲＯＩ設定期間中においても、曝射は実行されていないため、被検者の被曝量が累積することがない。また、ＡＢＣ制御も禁止されているため、プレ曝射時のＡＢＣ制御による被曝量累積も抑制することができる。 Even during this ROI setting period, since the exposure is not executed, the exposure dose of the subject does not accumulate. Moreover, since ABC control is also prohibited, exposure dose accumulation by ABC control during pre-exposure can be suppressed.
　ここで、図１０（１）に示される如く、定常時の放射線量ＸNの下での光電変換信号を階調信号に変換するときのヒストグラムは、定常時のダイナミックレンジ圧縮率ＤＲN領域のほぼ全域に亘って分布している。言い換えれば、定常時のダイナミックレンジ圧縮率ＤＲNを設定するにあたり、定常時の放射線量ＸNに基づいて予測している。 Here, as shown in FIG. 10 (1), the histogram when the photoelectric conversion signal under the radiation dose XN in the steady state is converted into the gradation signal is almost the entire dynamic range compression rate DRN region in the steady state. It is distributed over. In other words, when setting the dynamic range compression ratio DRN at the normal time, the prediction is made based on the radiation dose XN at the normal time.
　このため、前記図９のステップ３２２において放射線量を低下させると（ＸROI）、図１０（２）及び図１１（１）に示される如く、ヒストグラムの分布がＱＬ値の低い領域に偏ることになる（図１０（２）と図１１（１）は同一の特性図である）。 For this reason, if the radiation dose is reduced in step 322 of FIG. 9 (XROI), as shown in FIGS. 10 (2) and 11 (1), the distribution of the histogram is biased to a region having a low QL value. (FIG. 10 (2) and FIG. 11 (1) are the same characteristic diagram).
　そこで、図９のステップ３２４においてダイナミクレンジ圧縮率を高くするようにした（ＤＲROI)。この結果、図１１（２）に示される如く、ＱＬ値の低い方に偏ったヒストグラムの分布に適合した領域のダイナミックレンジとすることができる。 Therefore, in step 324 in FIG. 9, the dynamic range compression ratio is increased (DRROI). As a result, as shown in FIG. 11 (2), the dynamic range of the region adapted to the histogram distribution biased toward the lower QL value can be obtained.
　以上説明した如く本実施の形態では、放射線画像撮影システム１６において、動画像を撮影する場合、動画像である以上、被検者に静止画像撮影に比べて長い時間曝射を継続することになり、その分、被検者の被曝量を考慮する必要がある。 As described above, in the present embodiment, when a moving image is captured in the radiographic image capturing system 16, exposure to the subject is continued for a longer time compared to still image capturing as long as it is a moving image. Therefore, it is necessary to consider the exposure dose of the subject.
　そこで、本撮影前に実行される関心領域（ＲＯＩ）の設定中は、放射線曝射源２２Ａから曝射する放射線量を極力抑え（定常時よりも低くし）、当該低くした放射線量に基づくＱＬ値のヒクトグラムの分布に合わせて、ダイナミクレンジの圧縮率を定常時よりも高くした。このため、ＱＬ値の分布が偏ったとしても、ダイナミックレンジを無駄なく利用することができ、放射線量低下による被検者の被曝量軽減と、高精度のＲＯＩ設定とを両立することができる。 Therefore, during the setting of the region of interest (ROI) to be executed before the main imaging, the radiation dose exposed from the radiation exposure source 22A is suppressed as much as possible (lower than the normal time), and the QL based on the lowered radiation dose is set. The dynamic range compression rate was set higher than in the steady state to match the distribution of the value gramogram. For this reason, even if the distribution of the QL value is biased, the dynamic range can be used without waste, and both reduction of the exposure dose of the subject due to the radiation dose reduction and high-precision ROI setting can be achieved.
　なお、被検者へ曝射される放射線量を抑制する手段として、放射線曝射源２２Ａからの放射線量が変えずに、被検者との間に一時的（プレ曝射中）に放射線フィルタを介在させるようにしてもよい。 As a means for suppressing the radiation dose to be exposed to the subject, the radiation filter is temporarily (during pre-exposure) with the subject without changing the radiation dose from the radiation exposure source 22A. May be interposed.
　なお、放射線フィルタには、例えば、放射線曝射源２２Ａの曝射面に設置可能な所謂絞り機構部を含むものとする。すなわち、通常のカメラで言えば、ＮＤ（減光）フィルタをレンジに取り付けること、絞りを調整することは、露出を調整（低減）する役目としては同じである。なお、放射線フィルタは、例えば、特開２００１－１９０５３１号公報に、放射線フィルタが開示されているが、絞り機構部は、放射線の種類等によって、事実上、放射線フィルタが実用化できない場合の代用として適用可能である。 The radiation filter includes, for example, a so-called diaphragm mechanism that can be installed on the radiation surface of the radiation radiation source 22A. In other words, with a normal camera, attaching an ND (darkening) filter to the range and adjusting the aperture are the same in terms of the role of adjusting (reducing) exposure. As a radiation filter, for example, Japanese Patent Application Laid-Open No. 2001-190531 discloses a radiation filter. However, the diaphragm mechanism is a substitute for a case where the radiation filter cannot be practically used depending on the type of radiation. Applicable.
　さらに、本実施の形態では、電子カセッテ２０内の放射線検出器２６が、検出画素が二次元配列された所謂エリアセンサであるが、静止画像ほどフレームレートの高速化が要求されない動画像専用として、主走査方向画素が配列されたラインセンサと、このラインセンサを副走査方向へ移動させる走査機構部とを備え、走査機構部の走査で時系列で二次元の画像を取得する機能を備えた新たな電子カセッテを製作してもよい。また、図２に示す立位台４２或いは臥位台３６に、ラインセンサと走査機構部を内蔵してもよい。 Furthermore, in the present embodiment, the radiation detector 26 in the electronic cassette 20 is a so-called area sensor in which detection pixels are two-dimensionally arranged, but only for a moving image that does not require a higher frame rate than a still image, Newly equipped with a line sensor in which pixels in the main scanning direction are arranged and a scanning mechanism unit that moves the line sensor in the sub-scanning direction, and a function of acquiring a two-dimensional image in time series by scanning of the scanning mechanism unit An electronic cassette may be manufactured. Further, a line sensor and a scanning mechanism unit may be built in the standing table 42 or the standing table 36 shown in FIG.
　ラインセンサの場合、例えば、関心領域（ＲＯＩ）が設定された後、動画像を当該ＲＯＩ領域内に特定すれば、少なくとも副走査範囲を減縮することができるため、検出する階調信号の情報量を軽減することができる。 In the case of a line sensor, for example, after a region of interest (ROI) is set, if a moving image is specified in the ROI region, at least the sub-scanning range can be reduced. Can be reduced.
　図１２は、本実施の形態に係る放射線画像撮影システム１６において、被検者に対して動画による検査を行うときの工程における被曝量の累積値を、従来の比較例と比較した場合の特性図である。 FIG. 12 is a characteristic diagram in the case where the accumulated value of the exposure dose in the process of performing the examination by moving image for the subject in the radiographic imaging system 16 according to the present embodiment is compared with the conventional comparative example. It is.
　比較例では、関心領域設定開始時、すなわち、ＲＯＩを設定する段階から、動画撮影が実行され、かつＡＢＣ制御も実行されているため、被曝量は、本実施の形態の傾き（変化率）よりも大きい傾き（変化率）で所謂右肩上がりに累積されていることがわかる（図１２の鎖線参照）。しかも、検査終了時には、ＡＢＣ制御によって、正比例的（一次曲線）な増加に加え、二次曲線的に増加することになり、この一次曲線と二次曲線との間で大きな開きが発生する。 In the comparative example, since the moving image shooting is performed and the ABC control is also performed from the start of the region of interest setting, that is, from the stage of setting the ROI, the exposure amount is based on the inclination (change rate) of the present embodiment. It can be seen that a large slope (change rate) is accumulated in a so-called right-up direction (see the chain line in FIG. 12). Moreover, at the end of the inspection, ABC control increases in a quadratic curve in addition to a direct proportional (primary curve) increase, and a large gap occurs between the primary curve and the quadratic curve.
　これに対して、本実施の形態では、プレ曝射時においては当然被曝が発生するが、プレ曝射時の放射線エネルギーを定常よりも下げているため、比較例の傾き（変化率）よりも小さい（図１２のΔθ分の差）。このため、累積する被曝量も比較例より抑えることができる。 On the other hand, in the present embodiment, exposure naturally occurs during pre-exposure, but since the radiation energy during pre-exposure is lower than normal, the slope of the comparative example (rate of change) Small (difference by Δθ in FIG. 12). For this reason, the accumulated exposure dose can also be suppressed from the comparative example.
　また、ＲＯＩ設定中は、当然放射線が放射されていないため、被曝量が累積することがない。 Also, during the ROI setting, naturally, no radiation is emitted, so the exposure dose does not accumulate.
　さらに、関心領域設定終了時から、ＡＢＣ制御が開始されるため、前述した一次曲線（ＡＢＣ制御無し）と二次曲線（ＡＢＣ制御有り）との差も、比較例よりも抑制することができる。 Furthermore, since the ABC control is started from the end of the region of interest setting, the difference between the above-described primary curve (without ABC control) and the secondary curve (with ABC control) can be suppressed more than in the comparative example.
　以上説明したように、本実施の形態では、放射線画像撮影システム１６において、動画撮影の先だって、プレ曝射によって静止画像を撮影し、当該プレ曝射による静止画像に基づいて、ＲＯＩを設定し、ＲＯＩの設定が完了するまでは、ＡＢＣ制御を禁止するようにしたため、常に動画撮影並びにＡＢＣ制御を実行しながらのＲＯＩ設定中の被曝量よりも、大幅に被曝量を軽減することができる。さらに、ＲＯＩ設定用のプレ曝射での放射線エネルギーを低く設定し、その分、階調信号に変換するためのダイナミックレンジの圧縮率を高くしたため、被曝量がすくなくても正確かつ迅速にＲＯＩを設定することができる。 As described above, in the present embodiment, in the radiographic image capturing system 16, a still image is captured by pre-exposure prior to moving image capturing, and an ROI is set based on the still image generated by the pre-exposure, Until the ROI setting is completed, the ABC control is prohibited, so that the exposure dose can be significantly reduced as compared with the exposure dose during the ROI setting while always performing the moving image shooting and the ABC control. Furthermore, since the radiation energy in the pre-exposure for ROI setting is set low and the compression ratio of the dynamic range for converting to the gradation signal is increased accordingly, the ROI can be accurately and quickly performed even if the exposure dose is low. Can be set.
　（変形例） (Modification)
　上記実施の形態では、ＲＯＩ設定の際にプレ曝射によって静止画像を生成し、当該静止画像に基づいてＲＯＩ設定を行うことを基礎として、ＡＢＣ制御を禁止する、並びに、プレ曝射量を定常時よりも低くすると共に、その分ダイナミックレンジの圧縮率を高くする、といったベストパターンを説明したが、図１３に示される如く、ＡＢＣ制御を禁止する機能、プレ曝射量を定常時よりも低くする機能、ダイナミックレンジの圧縮率を調整する機能を省いてもよい。 In the above embodiment, on the basis that a still image is generated by pre-exposure at the time of ROI setting, and ROI setting is performed based on the still image, ABC control is prohibited and a pre-exposure amount is determined. The best pattern of lowering the dynamic range and increasing the compression ratio of the dynamic range has been explained. However, as shown in FIG. 13, the function for prohibiting ABC control and the pre-exposure amount are lower than those in the steady state. And the function of adjusting the compression ratio of the dynamic range may be omitted.
　日本出願特願２０１１－２０６４７０号の開示はその全体が参照により本明細書に取り込まれる。 The entire disclosure of Japanese Patent Application No. 2011-206470 is incorporated herein by reference.
　本明細書に記載された全ての文献、特許出願、および技術規格は、個々の文献、特許出願、および技術規格が参照により取り込まれることが具体的かつ個々に記された場合と同程度に、本明細書中に参照により取り込まれる。 All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually described to be incorporated by reference, Incorporated herein by reference.
　　１０　　放射線情報システム（ＲＩＳ）
　　１２　　端末装置
　　１４　　ＲＩＳサーバー
　　１４Ａ　　データベース
　　１６　　放射線画像撮影システム（撮影システム）
　　１８　　病院内ネットワーク
　　２０　　電子カセッテ
　　２２　　放射線曝射制御ユニット
　　２２Ａ　　放射線曝射源
　　２４　　放射線発生装置
　　２６　　放射線検出器　　２８　　クレードル
　　３０　　コンソール
　　３２　　放射線撮影室
　　３４　　立位台
　　３６　　臥位台
　　３８　　被検者
　　４０　　被検者
　　４２　　保持部
　　４４　　保持部
　　４６　　支持移動機構
　　５０　　基板
　　５２　　信号出力部
　　５３　　絶縁膜
　　５４　　センサ部
　　５６　　シンチレータ
　　５８　　透明絶縁膜
　　６０　　上部電極
　　６２　　下部電極
　　６４　　光電変換膜
　　６６　　電子ブロッキング膜
　　６８　　正孔ブロッキング膜
　　７０　　コンデンサ
　　７２　　電界効果型薄膜トランジスタ
　　７４　　ＴＦＴ基板
　　８０　　ディスプレイ
　　８２　　操作パネル
　　８４　　ＣＰＵ
　　８６　　ＲＯＭ
　　８７　　ＲＡＭ
　　８８　　ＨＤＤ
　　９０　　操作入力検出部
　　９２　　ディスプレイドライバ
　　９４　　Ｉ／Ｏ
　　９６　　Ｉ／Ｆ
　　９８　　バス
　　１００　　Ｉ／Ｆ
　　１０２　　画像処理制御ユニット
　　１０４　　システム制御部
　　１０６　　パネル制御部
　　１０８　　画像処理制御部
　　１１０　　バス
　　１２０　　放射線量調整部
　　１２２　　信号取得部
　　１２４　　階調信号解析部
　　１２５　　目的別静止画像生成指示部
　　１２６　　ダイナミックレンジ調整部
　　１２８　　静止画像生成部
　　１３０　　動画像編集部
　　１３２　　平均ＱＬ値演算部
　　１３４　　ＡＢＣ制御部
　　１３６　　基準ＱＬ値メモリ
　　１３８　　関心領域設定部
　　１４０　　ＲＯＩ確定前曝射制御部 10 Radiation Information System (RIS)
12 terminal device 14 RIS server 14A database 16 radiographic imaging system (imaging system)
18 Hospital network 20 Electronic cassette 22 Radiation exposure control unit 22A Radiation exposure source 24 Radiation generator 26 Radiation detector 28 Cradle 30 Console 32 Radiography room 34 Standing table 36 Supine table 38 Subject 40 Subject 40 42 holding part 44 holding part 46 support moving mechanism 50 substrate 52 signal output part 53 insulating film 54 sensor part 56 scintillator 58 transparent insulating film 60 upper electrode 62 lower electrode 64 photoelectric conversion film 66 electron blocking film 68 hole blocking film 70 capacitor 72 Field effect thin film transistor 74 TFT substrate 80 Display 82 Operation panel 84 CPU
86 ROM
87 RAM
88 HDD
90 Operation Input Detection Unit 92 Display Driver 94 I / O
96 I / F
98 Bus 100 I / F
102 Image processing control unit 104 System control unit 106 Panel control unit 108 Image processing control unit 110 Bus 120 Radiation dose adjustment unit 122 Signal acquisition unit 124 Gradation signal analysis unit 125 Purpose-specific still image generation instruction unit 126 Dynamic range adjustment unit 128 Still Image generation unit 130 Moving image editing unit 132 Average QL value calculation unit 134 ABC control unit 136 Reference QL value memory 138 Region of interest setting unit 140 Exposure control unit before ROI determination

Claims (12)

  1. 　設定された定常範囲の放射線エネルギーの放射線を、被検体に向けて曝射する放射線曝射手段から曝射され、かつ前記被検体を通過した放射線量を、複数の画素を備えた放射線検出器で受け、当該画素毎に受ける放射線量に応じた階調信号を出力する放射線画像撮影手段と、
    　前記放射線画像撮影手段から階調信号を取得して、所定のダイナミックレンジの下で当該階調信号を読み取り、１フレーム毎の静止画像情報を生成すると共に、前記静止画像を連続的に撮影することで前記被検体の動画像を生成する動画像情報生成手段と、
    　所定の制御周期で、前記放射線曝射手段から曝射する前記放射線の放射線エネルギーの設定値をフィードバック制御する制御手段と、
    　前記制御手段によるフィードバック制御禁止を指示し、かつ前記放射線曝射手段を指示して静止画像用のプレ曝射を実施し、前記放射線画像撮影手段から前記プレ曝射に基づく少なくとも１フレーム分の静止画像に相当する階調信号を取得し、当該階調信号から生成される静止画像の一部の領域を関心領域として設定する関心領域設定手段と、
    を有する放射線動画像撮影装置。     A radiation detector that includes a plurality of pixels that emits radiation having a radiation energy of a set steady range from a radiation exposure means that emits radiation toward the subject and passes through the subject. Radiation image capturing means for receiving and outputting a gradation signal corresponding to the radiation dose received for each pixel;
    Acquiring a gradation signal from the radiation image capturing means, reading the gradation signal under a predetermined dynamic range, generating still image information for each frame, and continuously capturing the still image And moving image information generating means for generating a moving image of the subject,
    Control means for feedback-controlling a set value of radiation energy of the radiation to be exposed from the radiation exposure means at a predetermined control cycle;
    Instructing prohibition of feedback control by the control means and instructing the radiation exposure means to perform pre-exposure for a still image, and at least one frame based on the pre-exposure from the radiation image photographing means A region-of-interest setting means for acquiring a gradation signal corresponding to an image and setting a partial region of a still image generated from the gradation signal as a region of interest;
    A radiological image capturing apparatus having
  2. 　前記関心領域設定手段により前記関心領域が設定された後は、前記制御手段によるフィードバック制御禁止を解除すると共に、前記動画像の生成を開始する請求項１記載の放射線動画像撮影装置。 The radiological moving image photographing apparatus according to claim 1, wherein after the region of interest is set by the region of interest setting unit, the prohibition of feedback control by the control unit is canceled and the generation of the moving image is started.
  3. 　前記放射線曝射手段による前記プレ曝射時の静止画像の撮影による被曝量が、前記動画像の撮影中の１フレーム分の静止画像の生成時の被曝量よりも抑制される請求項１又は請求項２記載の放射線動画像撮影装置。 The exposure amount by the still image capturing at the time of the pre-exposure by the radiation exposure means is suppressed more than the exposure amount at the time of generating the still image for one frame during the capturing of the moving image. Item 3. The radiological image capturing apparatus according to Item 2.
  4. 　前記被曝量の抑制が、前記放射線曝射手段に対して指示する放射線エネルギーを定常範囲よりも低くすることである請求項３記載の放射線動画像撮影装置。 4. The radiation moving image photographing apparatus according to claim 3, wherein the suppression of the exposure dose is to make the radiation energy instructed to the radiation exposure means lower than a steady range.
  5. 　前記被曝量が抑制され、かつ前記フィードバック制御が禁止されている間は、前記ダイナミックレンジの圧縮のパラメータである前記階調信号に対する前記画像情報の変化率を、フィードバック制御中よりも大きくするように調整する請求項１～請求項４の何れか１項記載の放射線動画像撮影装置。 While the exposure dose is suppressed and the feedback control is prohibited, the change rate of the image information with respect to the gradation signal that is a parameter of the compression of the dynamic range is set to be larger than that during the feedback control. The radiation moving image photographing apparatus according to any one of claims 1 to 4, wherein the radiation moving image photographing apparatus is adjusted.
  6. 　前記関心領域設定手段で関心領域を設定する際に適用する静止画像の範囲が、前記関心領域設定後に撮影する動画像の範囲よりも広い範囲である請求項１～請求項５の何れか１項記載の放射線動画像撮影装置。 The range of a still image applied when the region of interest is set by the region of interest setting means is a range wider than the range of a moving image captured after the region of interest is set. The radiation moving image photographing apparatus described.
  7. 　前記制御手段によるフィードバック制御の対象が、前記関心領域設定手段により設定された関心領域内の画像とする請求項１～請求項６の何れか１項記載の放射線動画像撮影装置。 The radiological image capturing apparatus according to any one of claims 1 to 6, wherein a target of feedback control by the control unit is an image in the region of interest set by the region of interest setting unit.
  8. 　放射線エネルギーの連続曝射による動画像撮影に先だって、被検体に向けて、静止画像用のプレ曝射を行い、
    　前記プレ曝射により前記被検体を通過する放射線エネルギーに基づいて、所定のダイナミックレンジの下で、少なくとも１フレーム分の静止画像に相当する階調信号を取得し、当該階調信号から生成される静止画像の一部の領域を関心領域として設定し、
    　当該関心領域を設定した後、所定の制御周期で、曝射する放射線の放射線エネルギーの設定値をフィードバック制御する処理を開始すると共に、動画像の撮影を開始する放射線動画像撮影装置用関心領域設定方法。     Prior to moving image capture by continuous exposure to radiation energy, pre-exposure for still images is performed toward the subject,
    Based on the radiation energy passing through the subject by the pre-exposure, a gradation signal corresponding to a still image of at least one frame is acquired and generated from the gradation signal under a predetermined dynamic range. Set a region of the still image as a region of interest,
    After setting the region of interest, the processing for feedback control of the set value of the radiation energy of the radiation to be exposed is started at a predetermined control cycle, and the region of interest setting for the radiation moving image capturing apparatus that starts capturing the moving image is started. Method.
  9. 　前記プレ曝射時の放射線の放射線エネルギーが、動画像撮影時よりも低く設定される請求項８記載の放射線動画像撮影装置用関心領域設定方法。 The region-of-interest setting method for a radiological moving image capturing apparatus according to claim 8, wherein the radiation energy of the radiation during the pre-exposure is set lower than that during moving image capturing.
  10. 　放射線エネルギーが低く設定された分、当該放射線エネルギーに対する階調信号の変化量が大きくなるように前記ダイナミックレンジの圧縮率を調整する請求項９記載の放射線動画像撮影装置用関心領域設定方法。 The region-of-interest setting method for a radiographic image capturing apparatus according to claim 9, wherein the compression ratio of the dynamic range is adjusted so that the amount of change in the gradation signal with respect to the radiation energy is increased by the amount of radiation energy set low.
  11. 　前記請求項１～請求項７の何れか１項記載の放射線動画像撮影装置と、
    　診断情報や施設予約の入力、閲覧、並びに放射線動画像の撮影依頼や撮影予約を行う端末装置と、
    　前記端末装置からの撮影依頼を受け付け、前記放射線動画像撮影装置における放射線画像の撮影スケジュールを管理すると共に、撮影された放射線動画像を一括管理するサーバーと、
    を有する放射線画像撮影システム。     The radiological image capturing apparatus according to any one of claims 1 to 7,
    A terminal device for inputting and browsing diagnostic information and facility reservations, as well as radiographic image capturing requests and imaging reservations;
    A server that accepts an imaging request from the terminal device, manages a radiographic imaging schedule in the radiographic video imaging device, and collectively manages radiographic images captured;
    A radiographic imaging system comprising:
  12. 　コンピュータを、前記請求項１～請求項６の何れか１項記載の放射線動画像撮影装置の動画像情報生成手段、制御手段、並びに関心領域設定手段として機能させる放射線動画像撮影制御プログラム。 A radiation moving image photographing control program causing a computer to function as moving image information generating means, control means, and region of interest setting means of the radiation moving image photographing apparatus according to any one of claims 1 to 6.
PCT/JP2012/071895 2011-09-21 2012-08-29 Fluoroscopy device, method for setting region of interest for fluoroscopy device, radiography system, and fluoroscopy control program WO2013042514A1 (en)

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