CN106780395B

CN106780395B - Method and device for removing motion blur in projection image of CBCT (cone beam computed tomography) system

Info

Publication number: CN106780395B
Application number: CN201611256543.5A
Authority: CN
Inventors: 徐璐; 王思睿; 陈鸣之
Original assignee: Shanghai United Imaging Healthcare Co Ltd
Current assignee: Shanghai United Imaging Healthcare Co Ltd
Priority date: 2016-12-30
Filing date: 2016-12-30
Publication date: 2019-12-20
Anticipated expiration: 2036-12-30
Also published as: CN106780395A

Abstract

The invention discloses a system for removing CBCTThe method for removing the motion blur in the projection image of the CBCT system comprises the steps of determining a region N occupied by a voxel in the projection image, wherein the size of the region N is related to the exposure time T of an angular speed W, CBCT system of the movement of a rack in the CBCT system, the pixel size L of an imaging unit and the distance D from the rotation center of the rack to the plane of the imaging unit; to be not less thanThe first projection images are acquired at a frame rate of (f) and synthesized every INT (FR × T) to generate projection images from which motion blur is removed. The projection image synthesized by the method eliminates the motion blur caused by the motion of the detector, and can obviously improve the spatial resolution and the signal-to-noise ratio of the projection image.

Description

Method and device for removing motion blur in projection image of CBCT (cone beam computed tomography) system

Technical Field

The present invention relates to image processing, and in particular, to a method and an apparatus for removing motion blur in a projection image of a CBCT system, and a CBCT system.

Background

Cone Beam Computer Tomography (CBCT) is a technology of reconstructing a tomography image by using a cone beam projection computer, and the principle is that an X-ray generator makes annular DR (digital radiation exposure) around a target body with lower ray dosage, then three-dimensional volume data are reconstructed in a computer by a data set after multiple exposures around the target body, compared with the traditional spiral CT, the difference of the CBCT is mainly on a detector, the traditional spiral CT adopts a linear array sensor and adopts an area array sensor, the spiral CT adopts quasi-one-dimensional data to reconstruct two-dimensional slice data, three-dimensional volume data are established by each two-dimensional slice data, and the CBCT directly adopts two-dimensional projection data to reconstruct three-dimensional volume data, so that the utilization rate of the X-ray by the CBCT is obviously improved compared with the spiral CT.

CBCT has become an important technological trend in medical C-arm systems due to its large z-axis coverage, high spatial resolution and its advantages that facilitate its integration with other clinical activities, such as interventional procedures.

One major application of CBCT is in obtaining three-dimensional images of a patient's blood vessels. For 3D vascular imaging, in order to make the vessels clearly visible, a CBCT scan session is performed by injecting a high contrast agent into the patient's vessels. During a vascular scan, the contrast agent should fill the vessels sufficiently, thus requiring the injection of a large amount of contrast agent.

However, high contrast agents may harm the health of the patient, so the dosage of the contrast agent is controlled. The required amount of contrast agent is related to the blood flow velocity and the CBCT scan time. Generally, the rate of blood flow is a natural attribute of the patient and is difficult to control. Therefore, it is important to increase the scanning speed of CBCT in this case. One potential application of CBCT is 3D cardiac imaging, in which case the scanning speed becomes more critical due to the fast beat rate of the patient's heart. In summary, CBCT systems with high scan speeds have great advantages in clinical applications.

As is well known, there are two scanning modes for CBCT:

1. step-by-step: and stopping the X-ray bulb tube (bulb tube for short) and the detector after the X-ray bulb tube and the detector move to the target positions for exposure, and moving the bulb tube and the detector to the next position after the exposure is finished.

2. The continuous formula is as follows: the bulb and detector are moved continuously, and exposure and integration are performed without interruption.

Based on the above scanning method, there are the following two solutions for obtaining a CBCT system with high scanning speed:

1. in the continuous scan mode, the C-arm gantry rotation speed is increased.

Typically, such a solution employs a fixed focal spot combination head or a fixed focal spot X-ray tube. When the gantry rotates at a higher speed, detector and focal spot induced motion blur may be introduced into the image. Fig. 1 shows a schematic view of the focal spot induced motion blur, which is illustrated in fig. 1 by a projection image of a central X-ray beam as an example. As can be seen from fig. 1, when the gantry rotates at high speed, the X-ray beam will pass through the shadow region of the object to be examined shown in fig. 1, and the X-ray beam passing through the shadow region will contribute to the pixel value formed by the central X-ray beam on the detector, thus reducing the quality of the obtained image, in particular the spatial resolution of the image. In order to overcome the motion blur caused by the focal spot, one current approach is to increase the power of the X-ray tube and reduce the exposure time, but this results in a large increase in cost and poor results due to the small pixel size of the detector, i.e. motion blur still exists. Another approach is to use some correction algorithms, including iterative reconstruction, blind deconvolution or non-blind deconvolution. However, the deconvolution method also only partially solves the motion blur, and the iterative reconstruction method significantly increases the computation time.

Therefore, the spatial resolution of the images obtained by the CBCT system with high scanning speed obtained in the above manner is still low.

2. In step-by-step scanning mode, a large area detector and a multi-source X-ray tube are employed.

In a step-and-scan mode with high scan speeds, the system is very unstable if conventional X-ray tubes and detectors are used, since each step of the gantry requires a strong force to accelerate and decelerate.

However, for X-ray tubes employing multiple light sources, the rotation of the gantry can be replaced by switching the light sources from position to position, so that the scan speed can be very high and no motion blur is introduced, but this solution depends on high cost and limited tube current.

Therefore, this approach has little clinical application.

In summary, the existing solution for obtaining high scanning speed is at the cost of image quality and computation time, the CBCT system with high scanning speed in continuous scanning mode obtains motion blur in the image, and the quality of the image does not meet the actual clinical requirement. Therefore, obtaining high quality images meeting practical clinical requirements in a CBCT system with high scanning speed is a problem to be solved.

Disclosure of Invention

In order to solve the above technical problem, the present invention provides a method for removing motion blur in a projection image of a CBCT system, comprising:

determining a region N occupied by a voxel in the projection image, the size of the region N being associated with an exposure time T of an W, CBCT system of angular velocity of gantry motion in a CBCT system, a pixel size L of an imaging unit, and a distance D of a center of gantry rotation to a plane of the imaging unit;

to be not less thanThe first projection images are acquired at a frame rate of (f) and synthesized every INT (FR × T) to generate projection images from which motion blur is removed, where INT (N) is the rounding of the area N and FR is the frame rate.

Further, the region N is obtained by the following formula:

further, the air conditioner is provided with a fan,

the synthesizing of the first projection images per INT (FR × T) to generate the projection images from which the motion blur is removed includes:

selecting the ith first projection image from INT (FR multiplied by T) first projection images as a reference first projection image; translating the jth first projection image by taking the reference first projection image as a referenceSo that the images of the same voxel in the reference first projection image coincide, where i ∈ [1, INT (FR × T)],j∈[1,INT(FR×T)]。

Further, the value range of N is: (1, 10].

Further, the method for removing the motion blur in the projection image of the CBCT system further comprises:

the method comprises the steps of controlling a focal spot of an X-ray source in a CBCT system to move along the direction opposite to the moving direction of the X-ray source, so that the focal spot of the X-ray source is static relative to a ground coordinate system.

The invention also provides a device for removing the motion blur in the projection image of the CBCT system, which comprises the following components:

a region determination module for determining a region N occupied by voxels in the projection image, the size of the region N being associated with an exposure time T of an angular velocity W, CBCT system of gantry motion in a CBCT system, a pixel size L of an imaging unit, and a distance D of a gantry rotation center to an imaging unit plane;

an image acquisition module for acquiring image data of at leastAcquiring a first projection image at a frame rate of (a), wherein int (N) is rounding the region N;

and an image synthesis module for synthesizing the first projection images per INT (FR × T) to generate projection images from which motion blur is removed, wherein FR is a frame rate.

Further, the region N is obtained by the following formula:

further, the image synthesis module includes:

a reference image selecting unit configured to select an ith first projection image as a reference first projection image from INT (FR × T) first projection images;

a synthesizing unit for translating the jth first projection image with the reference first projection image as a referenceSo that the images of the same voxel in the reference first projection image coincide, where i ∈ [1, INT (FR × T)],j∈[1,INT(FR×T)]。

Further, the apparatus for removing motion blur in CBCT system projection images further comprises:

the control module is used for controlling the focal spot of an X-ray source in the CBCT system to move along the direction opposite to the moving direction of the X-ray source, so that the focal spot of the X-ray source is static relative to a ground coordinate system.

The invention also provides a CBCT system, which comprises the device for removing the motion blur in the projection image of the CBCT system.

Compared with the prior art, the technical scheme of the invention has the following advantages:

by first determining a region N occupied by voxels in the projection images, the size of the region N being related to an exposure time T of an W, CBCT system of angular velocity of gantry motion in a CBCT system, a pixel size L of an imaging unit, and a distance D of a gantry rotation center to an imaging unit plane; then not less thanAcquiring a first projection image at a frame rate of (1); finally, the first projection images are synthesized every INT (FR × T) to generate a projection image from which motion blur is removed. Since it is not less thanThe first projection images are acquired at a high frame rate, and each INT (FR multiplied by T) first projection image is synthesized, so that the motion blur caused by the motion of a detector in a CBCT system with a high scanning speed can be removed, the spatial resolution and the signal-to-noise ratio of the images are improved, the quality of the images is improved, and the images meeting the actual clinical requirements are obtained.

Furthermore, the focal spot of the X-ray source in the CBCT system is controlled to move along the direction opposite to the moving direction of the X-ray source, so that the focal spot of the X-ray source is static relative to the ground coordinate system, further the motion blur caused by the focal spot in the CBCT system can be removed, the spatial resolution and the image quality of the image are further improved, and the finally obtained image can better meet the actual clinical requirement.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions and advantages of the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic illustration of focal spot induced motion blur;

FIG. 2 is a schematic illustration of detector induced motion blur;

FIG. 3 is a schematic illustration of a blurred projected image;

FIG. 4 is a flowchart of a method for removing motion blur in projection images of a CBCT system according to embodiment 1 of the present invention;

FIG. 5 is a flow chart of step 103;

FIG. 6 is a schematic illustration of a composite image;

FIG. 7 is a flowchart of a method for removing motion blur in projection images of a CBCT system according to embodiment 2 of the present invention;

FIG. 8 is a schematic view of an X-ray tube;

fig. 9 is a schematic view of the focal spot movement direction and the gantry movement direction of embodiment 2 of the present invention;

fig. 10 is a block diagram of an apparatus for removing motion blur in a projection image of a CBCT system according to embodiment 3 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

As described in the background section, when the conventional CBCT system employs step-by-step scanning, high-speed scanning is realized with a low dose, which depends on high cost and limited tube current, so that high-speed scanning is rarely realized by the step-by-step CBCT system. For a CBCT system that uses a continuous scanning mode to achieve a high scanning speed, the images obtained by the existing methods still fail to remove the motion blur in the projection images, resulting in low resolution of the finally obtained images and non-compliance with the actual clinical requirements. Therefore, the inventor starts from the source causing the projection image blurring, and starts from the motion blurring caused by the detector motion to remove the motion blurring in the projection image so as to improve the spatial resolution and the signal-to-noise ratio of the projection image, and obtains the image meeting the clinical requirement. Furthermore, the motion blur in the projection image is removed from the aspects of the motion blur caused by the motion of the detector and the motion blur caused by the focal spot, the spatial resolution and the signal-to-noise ratio of the projection image are further improved, and the quality of the obtained projection image is greatly improved.

Example 1:

the embodiment provides a method for removing motion blur in a projection image of a CBCT system. In this embodiment, a frame of the CBCT system is C-shaped, and an imaging unit is a detector, but the technical solution of the present invention is not limited thereto. The CBCT system in this embodiment includes a C-shaped gantry, an X-ray source and a detector, where the gantry is rotatable about a central axis of the gantry, and the X-ray source and the detector are respectively disposed at opposite ends of the gantry. During the operation of the CBCT system, the subject or the examined region is located between the X-ray source and the detector, and the radiation emitted from the X-ray source is projected onto the detector to generate a projection image.

Fig. 2 is a schematic diagram of motion blur caused by a detector, and as shown in fig. 2, during the high-speed rotation of the C-shaped gantry, the X-ray source and the detector cannot be kept absolutely stationary, so that the detector moves relative to the X-ray source, and at this time, the central X-ray beam shown in fig. 2 sweeps a certain area of the detector, thereby causing blur in the projection image.

Fig. 3 is a schematic diagram of a blurred projection image, where black parts are signals detected by a detector, and due to the motion of the detector, signals that should be acquired by one pixel unit are distributed in a plurality of pixel units, which results in a blurred projection image, and reduces the spatial resolution of the image and the signal-to-noise ratio of the image. The inventors propose to acquire projection images by increasing the frame rate and then to synthesize the acquired projection images to remove the blurring due to the detector motion. The following description is made by way of specific examples.

As shown in fig. 4, fig. 4 is a flowchart of a method for removing motion blur in a projection image of a CBCT system according to embodiment 1 of the present invention, where the method includes:

in step 101, a region N occupied by voxels in the projection image is determined, the size of the region N being related to the exposure time T of the angular velocity W, CBCT system of the gantry movement in the CBCT system, the pixel size L of the imaging unit, and the distance D of the gantry rotation center to the imaging unit plane.

In an alternative embodiment, the region N is obtained by the following formula:

step 102, not less thanThe frame rate of (a) acquires a first projection image, wherein int (N) is rounding the region N.

The exposure time of the CBCT system is T in step 101, so the frame rate of the detector is 1/T, and step 102 is executed to be not less thanThe first projection image is acquired at a frame rate of (1), which is equivalent to acquiring the image at an int (n) times or more of the original frame rate, and the acquisition of the first projection image can be realized by using a detector with a high frame rate in this step.

Step 103, synthesizing the first projection images of each INT (FR × T) to generate projection images from which motion blur is removed, wherein FR is the frame rate.

As an alternative embodiment, as shown in fig. 5, the step 103 of synthesizing the first projection images per INT (FR × T) to generate the projection images from which the motion blur is removed includes:

step 1030, selecting the ith first projection image from INT (FR multiplied by T) first projection images as a reference first projection image; wherein i belongs to [1, INT (FR x T) ].

Specifically, before performing step 1030, the method further includes the step of grouping the acquired first projection images:

each INT (FR × T) first projection image is divided into a group in turn. Each set of first projection images is a projection image of the same voxel.

Specifically, each INT (frx T) first projection image may be grouped according to an acquisition time of the first projection image or a corresponding gantry angle at which the first projection image is acquired.

And selecting one of the first projection images as a reference first projection image in each group of first projection images.

It should be noted that the above method processes a projection image acquired at a certain projection angle. Taking a projection angle of 5 degrees and INT (FR × T) ═ 3 as an example, three first projection images may correspond to projection angles of 5 degrees, 5.1 degrees, and 5.2 degrees, respectively. Specifically, the first projection image at which projection angle is used as the reference first projection image can be selected according to actual requirements, which is not specifically limited in the present invention, but the first projection images at different projection angles are used as the reference first projection image, and after the other first projection images are translated and synthesized with the reference first projection image as the reference to obtain the projection image without motion blur, the geometric relationship (how the two-dimensional projection image is mapped to the three-dimensional space) at the projection angle corresponding to the reference first projection image needs to be reconstructed when the projection image is subsequently reconstructed.

Step 1031 of translating the jth first projection image by taking the reference first projection image as a referenceSo that the images of the same voxel in the reference first projection image coincide, where i ∈ [1, INT (FR × T)]，j∈[1,INT(FR×T)]. When i is<j, in a certain direction, when i>j, the direction of translation and i<j is the opposite direction of d translation; i.e. iWhen j is the reference first projection image, no translation is made.

After the reference first projection image is selected, the reference first projection image may be translated in the horizontal direction according to the relative position relationship between the other first projection images of the group and the reference first projection image, so that the images of the same voxel in the reference first projection image are overlapped, and the specific translation amount is

The method of the present embodiment will be described in detail below with reference to fig. 6 as an example.

Taking int (n) ═ 3 as an example, or taking 3 pixel units occupied by blurred projection images of a single pixel on the detector as an example, the projection image in the first row in fig. 6 is a projection image acquired at a frame rate of 1/T, and when the projection images are acquired at this frame rate, there is relative motion between the detector and the X-ray source, and therefore motion blur due to the motion of the detector occurs. The projection images of the same voxel in fig. 6 are distributed in 3 pixel units as described above.

The three projection images of the second row in fig. 6 are such as to be exactly equal toThe first projection image is acquired at a frame rate 3 times that of the first line projection image, and INT (FR × T) ═ INT (n) ═ 3, the first line projection image is composed of 3 pictures, and the first line projection image is a projection image of the same voxel captured at different times.

In the present embodiment, when the first projection image in the second row is selected as the reference first projection image, that is, i is 1, the second first projection image (corresponding j is 2) and the third first projection image (corresponding j is 3) are translated so that the images of the same voxel in the reference first projection image overlap.

For the translation amount of the second projection image, i is 1, and j is 2, and the following formula is substituted to calculate:

for the translation amount of the third projection image, i is 1, and j is 3, and the following formula is substituted for calculation:

in the case of translation, corresponding to fig. 6, the images of the same voxel in the three first projection images can be superimposed by translating the entire second first projection image by one column to the left and translating the entire third first projection image by two columns to the left.

In fig. 6, the third row is a schematic diagram of translating the second projection image, and the fourth row is a schematic diagram of translating the third projection image.

Finally, the three first projection images are synthesized to generate a projection image with the motion blur removed at the projection angle. Specifically, the three translated first projection images are superimposed to synthesize one projection image from which the motion blur is removed. The last line in fig. 6 is the synthesized projection image. The synthesized projection images effectively remove the motion blur, and the spatial resolution of the synthesized projection images is higher, and the signal-to-noise ratio is the signal-to-noise ratio of each first projection imageAnd (4) doubling.

Of course, in a particular application scenario, the frame rate FR may be greater thanFor example, when INT (FR × T) is 5 and INT (n) is 3, a set of 5 pictures is formed, and projection images of the same voxel are taken at different times. If the first projection image is selected as the reference first projection image, that isAnd if i is 1, translating the second first projection image (corresponding to j is 2), the third first projection image (corresponding to j is 3), the fourth first projection image (corresponding to j is 4) and the fifth first projection image (corresponding to j is 5):so that the images of the same voxel in the reference first projection image coincide. Finally, the translated 5 first projection images are synthesized to generate a projection image with the motion blur removed at the projection angle. If the 3 rd image is selected as the reference image, the first and second images should be shifted to the right, and the fourth and fifth images should be shifted to the left. The method for removing motion blur in a projection image of a CBCT system provided in embodiment 1 of the present invention determines a region N occupied by a voxel after being blurred in the projection image, and then does not smaller than the region NThe frame rate of (1) acquires first projection images, and generates projection images from which motion blur is removed by translating and synthesizing INT (FR × T) first projection images acquired at a high frame rate. The projection image obtained by the method of the embodiment eliminates the motion blur caused by the motion of the detector, improves the spatial resolution of the acquired projection image and also obviously improves the signal-to-noise ratio of the projection image.

Example 2

This embodiment differs from embodiment 1 in that in addition to the motion blur due to the detector motion, the motion blur due to the focal spot is also considered in this embodiment, i.e. the motion blur due to both the detector and the focal spot is removed in this embodiment.

As shown in fig. 7, fig. 7 is a flowchart of a method for removing motion blur in a projection image of a CBCT system according to embodiment 2 of the present invention, where the method includes:

And 104, controlling the focal spot of an X-ray source in the CBCT system to move along the direction opposite to the moving direction of the X-ray source so that the focal spot of the X-ray source is static relative to a ground coordinate system.

The steps 101-103 in this embodiment are similar to those in embodiment 1, and are not described herein again.

In the CBCT system, the X-ray source is not ideal to be a point light source, but has a focal spot with a certain shape, and during the high-speed movement of the gantry, the focal spot is moving, and a certain area is swept during the exposure time, please continue to refer to fig. 1, as shown in fig. 1, when the X-ray source rotates with the gantry at a high speed, the X-ray beam passes through the shadow area of the object to be detected shown in fig. 1, and the X-ray beam passing through the shadow area also contributes to the pixel value formed by the central X-ray beam on the detector, the movement of the focal spot makes the projection image generated by the central X-ray beam passing through the object to be detected on the detector blurred, and in order to remove the blurring of the projection image caused by the movement of the focal spot, in this embodiment, the focal spot of the X-ray source in the CBCT system is controlled to move in the, such that the focal spot of the X-ray source is stationary with respect to a ground coordinate system. In addition, in the present embodiment, the X-ray source is taken as an X-ray tube for example, and those skilled in the art know that the X-ray source may also be an acceleration tube, and the present invention is not limited thereto. Fig. 8 is a schematic view of an X-ray tube, as shown in fig. 8, the X-ray tube including: the cathode comprises an anode 1, an anode target 2 and a cathode filament 4, wherein after voltage is applied between the anode target 2 and the cathode filament 4, electrons 3 of the cathode move towards the anode target 2, and the high-speed electrons 3 bombard the anode target 2 to generate X rays.

Fig. 9 is a schematic diagram of the focal spot moving direction and the gantry moving direction of embodiment 2 of the present invention, as shown in fig. 9, which is illustrated as a gantry moving to the right in fig. 9, and during the gantry moving at a high speed, the focal spot of the X-ray tube is controlled to move from the position of the right box illustrated in fig. 9 to the position of the left box illustrated in fig. 9 in the direction opposite to the gantry moving direction, i.e., the direction indicated by the dotted line in fig. 9. The circular ring in fig. 9 schematically represents the anode of the X-ray tube, and when the focal spot of the X-ray tube is controlled to move in the direction opposite to the moving direction of the X-ray tube, the focal spot of the X-ray tube is moved relative to the anode coordinate system of the X-ray tube, and is stationary relative to the ground coordinate system. In the process of high-speed rotation of the stand, by controlling the focal spot of the X-ray tube to move along the direction opposite to the moving direction of the stand, the motion blur caused by the focal spot movement can be removed, and further the spatial resolution and the signal-to-noise ratio of the acquired projection image can be improved.

As can be known from fig. 8, electrons 3 generated by the cathode in the X-ray tube bombard the anode target 2 to form a focal spot, and therefore, in this embodiment, the focal spot of the X-ray tube is controlled to move in a direction opposite to the moving direction of the X-ray tube during the high-speed movement of the gantry, specifically, a magnetic field is added between the anode target 2 and the cathode filament 4, and the moving direction of the electrons can be opposite to the moving direction of the gantry due to the lorentz force generated by the magnetic field. And the control of the movement of the focal spot of the X-ray source in the CBCT system along the direction opposite to the movement direction of the X-ray source is realized, and the movement distance and the movement speed are the same as those of the X-ray source, so that the focal spot of the X-ray source is static relative to a ground coordinate system. By controlling the focal spot of the X-ray source to move in a direction opposite to the direction of movement of the X-ray source, the movement of the focal spot may compensate for the movement of the X-ray source, such that during the acquisition of the projection image the effective focal spot appears to be fixed in position in space with respect to the detector, thereby removing blurring of the projection image caused by the movement of the focal spot.

It should be noted that, for simplicity of description, the above-mentioned method embodiments are described as a series of acts or combination of acts, but those skilled in the art will recognize that the present invention is not limited by the order of acts, as some steps may occur in other orders or concurrently in accordance with the invention. Further, those skilled in the art should also appreciate that the embodiments described in the specification are preferred embodiments and that the acts and modules referred to are not necessarily required by the invention.

The method for removing motion blur in a projection image of a CBCT system in this embodiment further controls a focal spot of an X-ray source to move along a direction opposite to a direction of movement of the X-ray source on the basis of removing the projection image blur caused by the movement of a detector in embodiment 1, thereby effectively removing the blur of the projection image caused by the movement of the focal spot, further improving the spatial resolution and the signal-to-noise ratio of the projection image, and improving the quality of the projection image to a great extent, so that the finally obtained projection image better meets the actual clinical requirements.

Example 3

As shown in fig. 10, fig. 10 is a block diagram of a structure of an apparatus for removing motion blur in a CBCT system projection image according to embodiment 3 of the present invention, and as shown in fig. 10, the apparatus for removing motion blur in a CBCT system projection image includes:

and an image synthesizing module for synthesizing the first projection image of each INT (FR × T) to generate a projection image from which motion blur is removed, FR being a frame rate.

As an alternative embodiment, the region N is obtained by the following formula:

as an alternative embodiment, the image synthesis module comprises:

a synthesizing unit for translating the jth first projection image with the reference first projection image as a referenceSo that the images of the same voxel in the reference first projection image coincide, where i ∈ [1, INT (FR × T)],j∈[1,INT(FR×T)]. As an alternative embodiment, the apparatus for removing motion blur in projection images of CBCT system of this embodiment further includes:

For a specific implementation of the apparatus for removing motion blur in a CBCT system projection image in this embodiment, reference may be made to an implementation of a method for removing motion blur in a CBCT system projection image, and details are not described here again.

The embodiment also provides a CBCT system, which includes the device for removing the motion blur in the projection image of the CBCT system.

The integrated units or modules in the above embodiments, if implemented in the form of software functional units and sold or used as independent products, may be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing one or more computer devices (which may be personal computers, servers, network devices, etc.) to execute all or part of the steps of the method according to the embodiments of the present invention.

In addition, functional units or modules in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A method for removing motion blur in projection images of a CBCT system, comprising:

to be not less thanAcquiring a first projection image, and synthesizing every INT (FR x T) first projection images to generate a projection image with motion blur removed, wherein INT (N) is the rounding of the area N, and FR is the frame rate;

selecting the ith first projection image from INT (FR multiplied by T) first projection images as a reference first projection image;

and translating the jth first projection image by taking the reference first projection image as a reference so as to enable images of the same voxel in the reference first projection image to coincide, wherein i belongs to [1, INT (FR multiplied by T) ], and j belongs to [1, INT (FR multiplied by T) ].

2. The method for removing motion blur in CBCT system projection images of claim 1, wherein the region N is obtained by the following formula:

3. the method for removing motion blur in projection images of CBCT system as claimed in claim 1, wherein before selecting the ith projection image as the reference first projection image from INT (frx T) first projection images, further comprising: a step of grouping the acquired first projection images; each group of first projection images are projection images of the same voxel;

the selecting the ith first projection image as the reference first projection image from the INT (FR x T) first projection images comprises: selecting one of the first projection images as a reference first projection image in each group of first projection images;

the translating the jth first projection image so that images of the same voxel in the reference first projection image coincide with each other with the reference first projection image as a reference includes: translating the jth first projection image by taking the reference first projection image as a referenceSo that the images of the same voxel in the reference first projection image coincide.

4. The method for removing motion blur in CBCT system projection images of claim 1, wherein the range of values of N is: (1,10].

5. The method for removing motion blur in CBCT system projection images of claim 1, further comprising:

6. An apparatus for removing motion blur in projection images of a CBCT system, comprising:

an image acquisition module for acquiring image data of at leastAcquiring a first projection image at a frame rate of (a), wherein the region N is rounded;

an image synthesizing module for synthesizing each INT (FR × T) pieces of the first projection image to generate a projection image from which motion blur is removed, where FR is a frame rate; the image synthesis module includes:

and a synthesizing unit, which is used for translating the jth first projection image by taking the reference first projection image as a reference so as to enable the images of the same voxel in the reference first projection image to coincide, wherein i belongs to [1, INT (FR × T) ], and j belongs to [1, INT (FR × T) ].

7. The apparatus for removing motion blur in projection images of CBCT system as claimed in claim 6, wherein said region N is obtained by the following formula:

8. the apparatus for removing motion blur in CBCT system projection images of claim 6, wherein the image composition module is further configured to:

grouping the acquired first projection images; each group of first projection images are projection images of the same voxel; selecting one of the first projection images as a reference first projection image in each group of first projection images;

the synthesis unit is used for translating the jth first projection image by taking the reference first projection image as a referenceSo that the images of the same voxel in the reference first projection image coincide.

9. The apparatus for removing motion blur in projection images of CBCT system as claimed in claim 6, further comprising:

10. A CBCT system comprising the apparatus for removing motion blur in projection images of a CBCT system as claimed in any one of claims 6 to 9.