WO2005060832A1 - 超音波診断装置および超音波イメージング方法 - Google Patents
超音波診断装置および超音波イメージング方法 Download PDFInfo
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- WO2005060832A1 WO2005060832A1 PCT/JP2004/018260 JP2004018260W WO2005060832A1 WO 2005060832 A1 WO2005060832 A1 WO 2005060832A1 JP 2004018260 W JP2004018260 W JP 2004018260W WO 2005060832 A1 WO2005060832 A1 WO 2005060832A1
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- ultrasonic
- correction
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- depth
- dynamic range
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
Definitions
- the present invention relates to an apparatus and a method for capturing an ultrasonic image as a diagnostic image of a subject.
- An ultrasonic diagnostic apparatus transmits and receives an ultrasonic beam to and from a subject using an ultrasonic probe, reconstructs an ultrasonic image based on a received signal output from the ultrasonic probe, and reconstructs an ultrasonic image.
- the configured ultrasonic image is displayed on the display screen.
- the ultrasonic beam is formed by a plurality of transducers arranged in an ultrasonic probe, having a focal point by transmitted or received ultrasonic waves.
- the reflected echo generated by the subject force is attenuated in the process of propagating inside the subject.
- the image quality of the ultrasound image affected by this attenuation is degraded, for example, a signal as diagnostic information is buried in noise. Therefore, it has been practiced to set the correction data exponentially as a function of the depth of the subject and to correct the received signal based on the set correction data, thereby improving the image quality of the ultrasonic image (for example, see Patent Document 1).
- Patent Document 1 Japanese Patent Application Laid-Open No. Hei 4 40945
- An object of the present invention is to realize an ultrasonic diagnostic apparatus and an ultrasonic imaging method that are more suitable for improving the image quality of an ultrasonic image.
- An ultrasonic diagnostic apparatus of the present invention provides an ultrasonic probe that transmits and receives ultrasonic waves to and from a subject, a transmission unit that supplies a drive signal to the ultrasonic probe, and an ultrasonic probe.
- Receiving means for processing a received signal output from the receiver, and a supersonic based on the received signal output from the receiving means.
- Display means for displaying a wave image, and means for correcting a reception signal output from the reception means in accordance with the beam shape of the ultrasonic beam transmitted and received by the ultrasonic probe and the depth of the subject It is characterized by having.
- the ultrasonic beam of at least one of the ultrasonic transmitting beam and the ultrasonic receiving beam may have various factors such as the position of the focal point and the number of transducers forming the diameter of the ultrasonic probe.
- the beam shape is determined by the element.
- Such an ultrasonic beam has a shape in which the aperture force is narrowed down to the focal point, and expands after the focal point.
- the ultrasonic beam has a different beam cross-sectional area in the depth direction of the subject, the beam intensity varies in the depth direction of the subject. Due to this, the received signal output from the ultrasonic probe is affected by both the shape of the ultrasonic beam and the depth of the subject.
- the reception signal after the correction becomes the same as the shape of the ultrasonic beam.
- the signal is less affected by the depth of the subject.
- the subject power can be reduced.
- a faithfully displayed ultrasonic image can be displayed.
- the correcting means corrects the dynamic range of the received signal from which the power of the receiving means is also output, based on the dynamic range calculated according to the beam shape of the ultrasonic beam and the depth of the subject.
- Dynamic range correction means can be used.
- the signal intensity of the reception signal output from the reception means is based on the beam intensity calculated corresponding to the beam shape of the ultrasonic beam and the depth of the subject.
- the receiving means may include means for converting a received signal output from the ultrasonic probe into a digital signal based on a sampling clock.
- the correction means may include one or more sensors set in the depth direction of the subject based on the sampling clock. For each sampling point, the converting means can also correct the received signal output.
- the correction means may include a calculation means for calculating correction data.
- the calculating means calculates the frequency of the drive signal, the wave number of the drive signal, the coordinates of the focal point of the ultrasonic beam, the number of transducers forming the aperture of the ultrasonic probe, and the focus data for forming the ultrasonic beam.
- Correction data can be calculated based on parameters including at least one.
- the correction means may include a calculation means for calculating correction data.
- the calculating means calculates one correction data corresponding to the beam shape of one ultrasonic beam and the depth of the subject, and calculates one correction data while a reception signal corresponding to one ultrasonic beam is received.
- Other correction data can be calculated according to the beam shape of another ultrasonic beam different from the ultrasonic beam and the depth of the subject.
- the dynamic range calculated in accordance with the beam shape of the ultrasonic beam can be displayed as a graph as a function of the depth of the subject.
- the beam intensity calculated corresponding to the beam shape of the ultrasonic beam can be displayed as a graph as a function of the depth of the subject.
- An ultrasonic imaging method includes a step of calculating correction data corresponding to a beam shape of an ultrasonic beam formed by an ultrasonic probe and a depth of a subject; Transmitting a driving signal to the ultrasonic probe force to transmit an ultrasonic wave to the subject; and a receiving step of processing a reception signal output from the ultrasonic probe in response to the transmitting step.
- Receiving step power The method includes a step of correcting an output received signal based on correction data, and a step of displaying an ultrasonic image based on the received signal output from the correction step.
- a dynamic range corresponding to the beam shape of the ultrasonic beam and the depth of the subject can be calculated.
- the dynamic range of the reception signal output from the reception step can be corrected based on the dynamic range calculated in the correction data calculation step.
- a beam intensity corresponding to the beam shape of the ultrasonic beam and the depth of the subject can be calculated.
- the signal strength of the received signal from which the reception step power is also output is calculated. Can be corrected.
- correction data calculation step correction data corresponding to at least one of the ultrasonic transmission beam and the ultrasonic reception beam can be calculated.
- the received signal output from the ultrasonic probe can be converted into a digital signal based on a sampling clock.
- the reception signal output at the reception step can be corrected for each of one or more sampling points set in the depth direction of the subject based on the sampling clock.
- the frequency of the drive signal, the wave number of the drive signal, the coordinates of the focal point of the ultrasonic beam, the number of transducers forming the aperture of the ultrasonic probe, and the ultrasonic beam are calculated.
- the correction data can be calculated based on a parameter including at least one of the focus data to be formed.
- a step of calculating one correction data corresponding to a beam shape of one ultrasonic beam and a depth of the subject, and a step of receiving a signal corresponding to one ultrasonic beam are performed. While receiving the signal, the method may include calculating another correction data corresponding to the beam shape of another ultrasonic beam different from the one ultrasonic beam and the depth of the subject. .
- the dynamic range calculated according to the beam shape of the ultrasonic beam can be displayed as a graph as a function of the depth of the subject.
- the beam intensity calculated corresponding to the beam shape of the ultrasonic beam can be displayed as a graph as a function of the depth of the subject.
- FIG. 1 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus according to a first embodiment to which the present invention has been applied.
- FIG. 2 is a flowchart showing an entire process of the ultrasonic diagnostic apparatus of FIG. 1.
- FIG. 3 is a conceptual diagram for explaining an operation of a dynamic range correction unit in FIG. 1.
- FIG. 4 is a display example of an ultrasonic image captured by the ultrasonic diagnostic apparatus of FIG. 1 and a comparative example captured by the apparatus of the reference embodiment.
- FIG. 5 is a diagram illustrating that the beam shape of an ultrasonic beam differs in the depth direction.
- FIG. 6 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus according to a second embodiment to which the present invention is applied.
- FIG. 7 is a flowchart showing an entire process of the ultrasonic diagnostic apparatus of FIG. 6.
- FIG. 8 is a conceptual diagram for explaining the operation of the signal strength correction unit in FIG. 6.
- FIG. 9 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus according to a third embodiment to which the present invention has been applied.
- FIG. 10 is a flowchart showing an entire process of the ultrasonic diagnostic apparatus of FIG. 9.
- FIG. 11 is a conceptual diagram for explaining the operation of the correction unit in FIG. 9.
- FIG. 1 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus 1 of the present embodiment.
- the ultrasonic diagnostic apparatus 1 includes an ultrasonic probe 10 for transmitting and receiving ultrasonic waves to and from a subject, and a transmission unit for supplying a drive signal to the ultrasonic probe 10. And a receiving means for processing a received signal output from the ultrasonic probe 10.
- the receiving means here includes a receiving circuit 16 that performs processing such as amplification on a received signal output from the ultrasonic probe 10, and converts the received signal output from the receiving circuit 16 into a digital signal based on a sampling clock.
- An analog-to-digital conversion unit 18 (hereinafter referred to as an AZD conversion unit 18) and a phasing addition unit 20 as software phasing addition means for performing a phasing addition process on a received signal output from the AZD conversion unit 18.
- a signal processing unit 22 that performs processing such as detection on the received signal output from the phasing addition unit 20.
- the ultrasonic diagnostic apparatus 1 based on correction data calculated in correlation with the beam shape of the ultrasonic beam transmitted / received by the ultrasonic probe 10 and the depth of the subject, And a dynamic range correction unit 24 as means for correcting the received signal output from the signal processing unit 22.
- the ultrasonic beam in the present embodiment means an ultrasonic wave transmitting beam and an ultrasonic wave receiving beam, but either one may be used.
- the ultrasonic probe 10 is formed by arranging a plurality of transducers. Each transducer is supplied from the transmission circuit 12
- the drive signal is converted into an ultrasonic wave, and the reflected echo generated by the subject force is converted into a received signal.
- the drive signal here is a pulse signal for transmitting ultrasonic waves.
- the transmission circuit 12 is provided in the transmission / reception unit 26 together with the reception circuit 16.
- the transmission / reception unit 26 outputs a drive signal output from the transmission circuit 12 to the ultrasonic probe 10, and a transmission / reception separation circuit that outputs a reception signal output from the ultrasonic probe 10 to the reception circuit 16.
- the ultrasonic probe 10 has a high-voltage switching switch for selecting a group of transducers that form a transmission aperture or a reception aperture of the ultrasonic probe 10.
- the receiving circuit 16 has a receiving amplifier that amplifies a received signal output from the ultrasonic probe 10.
- the receiving amplifier has a preamplifier that amplifies the received signal with a predetermined signal amplification factor, and a gain control amplifier that varies the signal amplification factor in accordance with the attenuation of the reflected echo caused by the depth of the ultrasonic reflection portion.
- a focus position determination unit 28 is connected to the transmission / reception unit 26.
- the focus position determination unit 28 outputs the set coordinates of the focal point of the ultrasonic transmission beam to the transmission / reception unit 26.
- a keyboard or mouse for inputting the coordinates of the focal point may be provided in the focus position determining unit 28.
- the AZD converter 18 has a clock generator that generates a sampling clock.
- the phasing addition section 20 includes a delay amount correction section 34 for digitally phasing the received signal output from the AZD conversion section 18 based on the focus data, and a memory 36 storing focus data provided to the delay amount correction section 34.
- an adder 38 that adds the received signals for each channel output from the delay amount corrector 34 and outputs the result to the signal processor 22.
- the signal processing unit 22 has a function of performing processing such as detection, filtering, and logarithmic compression on the reception signal output from the phasing addition unit 20, and an ultrasonic image (based on the processed reception signal). For example, it has a function of forming an image signal that is a basis of a B-mode image, a Doppler image, and an M-mode image).
- the image signal output from the signal processing unit 22 is sent to the dynamic range correction unit 24. Is output.
- the image signal output from the signal processing unit 22 is also appropriately referred to as a received signal.
- the dynamic range correction unit 24 has a dynamic range calculation unit 40 and a memory 42.
- the dynamic range calculation unit 40 calculates a dynamic range (hereinafter referred to as a correction dynamic range) as correction data correlated with the beam shape of the ultrasonic beam transmitted and received by the ultrasonic probe 10 and the depth of the subject. It has a function to do. For example, the frequency of the drive signal, the wave number of the drive signal, the coordinates of the focal point of the ultrasonic transmission beam or the ultrasonic reception beam, the size of the aperture of the ultrasonic probe 10, the ultrasonic transmission beam or the reception beam
- the correction dynamic range is calculated based on a parameter including at least one of the focus data for forming the correction data.
- the size of the aperture is obtained based on the number of transducers forming the transmission aperture or the reception aperture, and the size of each transducer.
- the dynamic range calculation unit 40 arranges the dynamic range for correction in a dynamic range table.
- the dynamic range table is a database in which correction dynamic ranges are arranged in correspondence with the depth of the subject (for example, the depth of a sampling point or a focus stage).
- the dynamic range table has an ultrasound beam profile as a function of the depth of focus.
- Such a dynamic range table is stored in the memory 42.
- the dynamic range calculator 40 corrects the dynamic range of the received signal output from the signal processor 22 based on the correction dynamic range. For example, based on the sampling clock of the AZD conversion unit 18, the reception signal output from the signal processing unit 22 is corrected for each sampling point set in the depth direction of the subject.
- the received signal instead of correcting the received signal for each sampling point, the received signal may be corrected for each focus stage having a plurality of sampling points.
- the dynamic range correction unit 24 calculates the first correction dynamic range based on the beam shape of the first ultrasonic beam and the depth of the subject, and corresponds to the first ultrasonic beam.
- the second dynamic range for correction can be calculated based on the beam shape of the second ultrasonic beam different from the first ultrasonic beam and the depth of the subject. That is, the dynamic range calculation unit 40 can calculate the dynamic range for correction in advance by time division processing. Or, the shape of the ultrasonic beam set in advance On the other hand, the corresponding dynamic range for correction can be stored in the dynamic range table 42 in advance.
- a digital scan converter 30 (hereinafter, referred to as DSC30) that converts the corrected reception signal output from the dynamic range correction unit 24 into a display signal and performs luminance matching processing on the reception signal.
- a display unit 32 for displaying an ultrasonic image based on the received signal output from the DSC 30 on a display screen.
- the ultrasonic probe 10 is brought into contact with the subject.
- the drive signal is supplied from the transmission circuit 12 to the ultrasonic probe 10
- the ultrasonic probe 10 irradiates the subject with an ultrasonic transmission beam.
- the reflected echo generated from the subject is converted into a received signal by being received by the ultrasonic probe 10.
- the received signal is amplified by the receiving circuit 16.
- the amplified received signal is converted into a digital signal by the AZD converter 18.
- the digitally received signal is formed by the phasing adder 20 as an ultrasonic wave receiving beam.
- the ultrasonic reception beam output from the phasing addition section 20 is output as an image signal by being subjected to predetermined processing by the signal processing section 22.
- the dynamic range of the image signal output from the signal processing unit 22 is corrected by the dynamic range correction unit 24.
- the corrected image signal is displayed as an ultrasonic image on the display unit 32 via the DSC 30.
- FIG. 2 is a flowchart showing the overall processing of the ultrasonic diagnostic apparatus 1 of FIG.
- FIG. 3 is a conceptual diagram for explaining the operation of the dynamic range correction unit in FIG. Although FIG. 3 shows processing in one focus stage for convenience, the same applies to processing in other focus stages.
- the dynamic range for correction D1 to D6 is calculated by the dynamic range calculation unit 40.
- the dynamic range for correction D1 to D6 is correction data correlated with the beam shape of the ultrasonic beam formed by the ultrasonic probe 10 and the depth of each of the reflection parts 46-1 to 46-7.
- the dynamic range calculation unit 40 also calculates the correction dynamic ranges D1 to D6 for the factor power related to the beam shape of the ultrasonic beam.
- the factors are the frequency of the drive signal supplied from the transmission circuit 12, the wave number of the drive signal, the coordinates of the focal point of the ultrasonic beam, the number of transducers forming the aperture of the ultrasonic probe 10, the phasing method, and the like. Is the parameter.
- the phasing method is transmission focus data for delaying the drive signal, and reception focus data for phasing the reception signal (for example, focus data stored in the memory 36).
- a general formula for setting the correction dynamic range D1 to D6 is represented by the following formula (1).
- the dynamic range is set as shown in the table.
- the correction dynamic range Dl-D6 is a unique dynamic range of the ultrasonic beam, and depends on the beam intensity at each of the reflection portions 46-1-46-7.
- Such correction dynamic ranges D1 to D6 are stored in the memory 42 as a dynamic range table after being associated with the sampling point or the depth of the focus step.
- FIG. 3C shows a dynamic range for correction D1 to D6 corresponding to the received signals S1 to S6.
- the dynamic range for correction D1 to D6 may be obtained from an actual measurement and a simulation.
- a drive signal is supplied to the ultrasonic probe 10 to transmit ultrasonic waves from the ultrasonic probe 10 to the subject.
- a drive signal is supplied from the wave transmitting circuit 12 to the ultrasonic probe 10 that has come into contact with the body surface of the subject.
- a plurality of drive signals are generated corresponding to the number of transducers included in the ultrasonic probe 10, and each of the generated drive signals is delayed by using transmission focus data based on the focal position. I have.
- the focus position is output from the focus position determination unit 28 to the transmission / reception unit 26 at a predetermined timing.
- a predetermined transducer group is selected by a high-voltage switching switch, thereby forming a transmission aperture.
- a drive signal is supplied to a group of transducers having a transmission aperture, ultrasonic waves are transmitted from the supplied transducers.
- Each transmitted ultrasonic wave forms an ultrasonic transmission beam.
- the formed ultrasonic transmission beam has a focal point at a predetermined distance in the transmission direction.
- the vertical axis in FIG. 3A indicates the depth of the subject, and the horizontal axis indicates the scanning address of the beam.
- a plurality of reflection portions 46-1-1 46-7 are scattered on the subject.
- Each reflection part 46-1—46—7 has a different size and acoustic impedance.
- the reflecting portions 46-1 to 46-7 have different depths except for the reflecting portion 46-6.
- the reflection part 46-6 has the same depth as the reflection part 46-1.
- the beam address of the ultrasonic probe 10 is initialized to the address A shown in FIG. 3A. Then, an ultrasonic transmission beam is emitted from the ultrasonic probe 10. In other words, the ultrasonic transmission beam is sequentially emitted to the reflecting portions 46-1 to 46-7 while changing the address in the scanning direction with the address A force.
- FIG. 3A shows a two-dimensional distribution in the depth direction and the scanning direction, the same applies to a three-dimensional distribution.
- the focal position of the ultrasonic transmission beam can be changed as appropriate.
- the reception signal output from the ultrasonic probe 10 is processed in accordance with the ultrasonic wave transmitting step (S101).
- the reflected echo generated from the reflecting portion 46-1—46-7 is received by the ultrasonic probe 10 and converted into a received signal.
- the converted reception signal is sequentially processed by the reception circuit 16, the AZD conversion unit 18, and the phasing addition unit 20, whereby an ultrasonic wave reception beam is formed.
- the formed ultrasonic receiving beam is focused at a predetermined depth of the subject.
- the ultrasonic receiving beam is output to the dynamic range correction unit 24 as received signals S1 to S6 as shown in FIG. 3B.
- the vertical axis in FIG. 3B indicates the depth of the subject, and the horizontal axis indicates the signal intensity.
- the signal strength of the received signals S1 to S6 corresponds to, for example, luminance information when an image signal is formed.
- FIG. 3B shows the signal intensities of the received signals S1 to S6 as projected for each depth.
- the reflection part 46-1 and the reflection part 46-6 have the same depth, since the signal strength of the reception signal corresponding to the reflection part 46-1 is larger, the reception signal corresponding to the reflection part 46-1 is larger. As the received signal S 1.
- the reception signal SI-S6 output from the ultrasonic receiving step (S102) is corrected based on the dynamic range for correction.
- the received signal S1 is input to the dynamic range correction unit 24.
- the dynamic range calculator 40 reads the dynamic range D1 for correction from the memory 42.
- the dynamic range D1 for correction is arranged in the dynamic range table, and the dynamic range table power is also extracted corresponding to the depth of the reflection part 46-1.
- the signal strength of the received signal S1 is corrected by the dynamic range calculation unit 40 based on the correction dynamic range D1.
- FIG. 3D shows the corrected received signals DN1 to DN6 processed in this way.
- the received signals DN1 to DN6 are signals in which the inherent dynamic range of the ultrasonic beam is considered.
- Equation 2 The correction calculation in this step is performed based on, for example, Equation 2.
- Equation 2 k indicates the number of received signals to be corrected. In this embodiment, the value of k is 1 to 6. The force may be changed as appropriate.
- a indicates a coefficient for correcting the signal intensity attenuated when the reflected echo propagates in the subject.
- ⁇ Ultrasonic image display process (SI 04)> An ultrasonic image based on the received signals DN1 to DN6 output from the correction step (S103) is displayed on the display screen.
- the received signals DN1 to DN6 are converted into display signals by the DSC 30, and are subjected to luminance adjustment processing.
- the received signals DN1 to DN6 output from the DSC 30 are displayed on the display screen of the display unit 32 as ultrasonic images.
- the dynamic range for correction D1 to D6 is displayed as a graph alongside the ultrasonic image as a function of the depth of the reflection area 46-1 to 46-7.
- the dynamic range D1-D6 for correction is visually grasped by the graph display.
- the ultrasonic wave transmitting beam or the ultrasonic wave receiving beam has a shape which is narrowed down to the focal point focal point, and spreads out after the focal point.
- a difference occurs in sound pressure or reflection intensity depending on the depth of each of the reflection portions 46-1-1-46-7.
- the ultrasonic beam has a different beam cross-sectional area in the depth direction of the subject, the beam intensity differs in the depth direction of the subject. Due to this, the received signal output from the signal processing unit 22 is influenced by both the shape of the ultrasonic beam and the depth of the reflection part 46-1 to 46-7.
- the reception signals S1-S6 output from the signal processing section 22 are corrected in correlation with the shape of the ultrasonic beam and the depth of the reflection portions 46-1-146-7.
- the corrected reception signals DN1 to DN6 are signals in which the influence of the shape of the ultrasonic beam and the depth of the reflection portion 46-1 to 46-7 is reduced.
- FIG. 4A is a display example of an ultrasonic image captured by a phantom by the ultrasonic diagnostic apparatus of the present embodiment.
- FIG. 4B is a display example of an ultrasonic image captured by a phantom using the ultrasonic diagnostic apparatus according to the reference embodiment.
- the dynamic range at the time of displaying an ultrasonic image is set to be constant (for example, 100 dB) regardless of the depth of the force reflection portion.
- a reflected echo generated by a shallow reflecting portion force has a large signal strength
- a reflected echo generated by a deep reflecting portion force has a small signal intensity due to attenuation in the subject. Therefore, if the image is displayed according to the dynamic range of the received signal corresponding to the shallow reflecting portion, the contrast of the image corresponding to the deep reflecting portion may be reduced.
- the information corresponding to the shallow reflection part may be lost due to luminance saturation.
- the ultrasonic beam having the widest dynamic range at each depth of the reflection portion is used as a reference.
- the dynamic range in which all the received signals can be expressed is set, so that the display is wider than the dynamic range inherent in the received signals.
- unnecessary components are displayed on the ultrasonic image as noise.
- the dynamic range of the received signal is set in correlation with the beam shape of the ultrasonic beam. That is, an ultrasonic image faithful to the dynamic range of the ultrasonic beam at each depth of the reflection portions 46-1-147-7 is displayed. Therefore, the ultrasonic image shown in FIG. 4A is compared with FIG. 4B in that there is no loss of a signal as diagnostic information, and unnecessary components that become noise are reduced. Such an effect becomes more remarkable in a portion where the inherent dynamic range of the ultrasonic beam is narrowed. For example, it is remarkable in a shallow part when a beam is formed using a variable aperture.
- the corrected received signals DN1 to DN6 are weighted by a function according to the dynamic range D1 to D6 inherent to the ultrasonic beam. Based on the received signals DN1 to DN6 after such correction, the dynamic range for displaying an ultrasonic image is set for each depth. Therefore, the ultrasonic image displayed on the display unit 32 has a reduced noise component and more faithfully represents the difference in acoustic impedance of the reflection portions 46-1 to 46-7.
- the present embodiment has been made by paying attention to the fact that the ultrasonic beam shape changes in the depth direction of the subject. That is, the ultrasonic beam shape changes in the depth direction of the subject due to the focal position of the ultrasonic transmission beam, the size of the transmission aperture, the size of the reception aperture, the phasing method of the ultrasonic reception beam, etc. . Therefore, the intensity of the ultrasonic beam (the magnitude of the sound field) differs depending on the depth direction. If the shape of the ultrasonic beam differs in the depth direction, the dynamic range of the ultrasonic beam changes accordingly.
- the image quality of the ultrasonic image can be improved by appropriately setting the dynamic range of the image signal in the depth direction of the subject in correlation with the ultrasonic beam.
- the dynamic range of the received signal may be relatively wide, for example, exceeding 70 dB.
- the dynamic range when displayed as an ultrasonic image is set for each depth of the reflection site in correlation with the ultrasonic beam shape.
- the shape of the ultrasonic beam changes at any time as the focal position of the ultrasonic beam or the phasing method changes.
- the dynamic range table is automatically updated by the dynamic range calculation unit 40 following the change in the ultrasonic beam shape. Therefore, the usability and operability of the device are improved.
- the present invention has been described with reference to the first embodiment, the present invention is not limited to this.
- the correction processing shown in FIG. 2 may be executed in a unit of a beam address or in a unit of a frame.
- the processing is performed on a frame basis, as described with reference to FIG. 3A, when there are a plurality of reflection portions (for example, the reflection portions 46-1, 46-6) at the same depth, the received signal strength is high. Should be used as the basis.
- the present invention is not limited to capturing a B-mode image (tomographic image), and can be applied to capturing a Doppler image or an M-mode image.
- the received signal input to the dynamic range correction unit 24 is an output signal of the signal processing unit 22. Instead, the received signal is output from the signal processing unit 22 or the output signal of the phasing addition unit 20. Or the output signal of the AZD converter 18. In short, the received signal output from the receiving means may be output to the dynamic range correction unit 24.
- the dynamic range of the transmission / reception system circuit of the ultrasonic diagnostic apparatus 1 be wider than the inherent dynamic range of the ultrasonic beam transmitted and received by the ultrasonic probe 10.
- FIG. 5A is a conceptual diagram of a plurality of sampling points T1 and TP (P: a natural number of 2 or more) set in the depth direction of the subject.
- FIG. 5B is a diagram showing a beam shape of a reception beam formed at each of the focus stages A to D.
- Figure 5C shows the beam shape of the ultrasonic transmission beam.
- a plurality of sampling points T1 and TP are set in the depth direction of the subject. Each interval between the sampling points T1 and TP is set equal to the sampling clock interval of the AZD converter 18.
- the plurality of sampling points T1 to TP are divided into focus stages A to D, for example, every four. For example, sampling points T1 to T4 belong to focus stage A. Note that the number of sampling points belonging to one focus stage is appropriately determined within a range that does not hinder diagnosis.
- Common focus data is set for each of such focus stages A to D.
- the set focus data is stored in the memory 36.
- the reception focus data is a delay amount or a minute delay amount for phasing each reception signal output from each transducer of the ultrasonic probe 10, and is switched for each of the focus stages A to D.
- the focus data stored in the memory 36 is read according to a control command. Based on the read focus data, the reception signal output from the AZD conversion unit 18 is delayed and phased by the phasing addition unit 20. As a result, ultrasonic receiving beams corresponding to the respective sampling points T1 and TP are respectively formed.
- so-called dynamic focus is performed.
- the dynamic focus is a method of focusing a beam in a relatively wide range in the depth direction by focusing on a part at a shallow depth, a part depth, and a part.
- focus data here, independent focus data is set for each of the focus stages A to D within a range that does not affect the diagnosis.
- the total number of focus data can be reduced as compared with the case where each sampling point T1 is set for each TP, and the storage area of the memory 36 can be used effectively.
- the beam shape (beam profile) of the ultrasonic receiving beam differs in the depth direction of the subject due to the difference in the focus data for each of the focus stages A to D.
- Fig. 5B shows the received beam shape corresponding to sampling point T1 belonging to focus stage A, the received beam shape corresponding to sampling point T5 belonging to focus stage B, and the sampling point belonging to focus stage C in order from the top. Show the received beam shape corresponding to T (P-8) and the received beam shape corresponding to sampling point ⁇ ( ⁇ -4) belonging to focus stage D! / ⁇ .
- the ultrasonic wave reception beam has a beam shape in the depth direction of the subject. Different.
- the depth differs slightly between a plurality of sampling points (for example, sampling points T1 and T4) belonging to the same focus stage (for example, focus stage A).
- the beam shape of the wave beam is also slightly different.
- the beam shape of the ultrasonic wave receiving beam also differs in the depth direction due to the variable aperture.
- the variable aperture is a method of automatically reducing the aperture width to a shallower portion. With the variable aperture, it is possible to suppress the spread of the reflected echo generated at the sampling points (for example, sampling points T1 and T2) close to the ultrasonic probe 10. In the case of performing such a variable aperture, the size of the aperture for receiving the reflected echo, that is, the number of transducer elements forming the received aperture changes. Therefore, the beam shape of the ultrasonic receiving beam differs in the depth direction.
- the beam shape of the ultrasonic transmission beam also differs in the depth direction.
- an ultrasonic transmission beam is formed by focusing on one point.
- the ultrasonic transmission beam is narrowed from the ultrasonic probe 10 to the focal point 41, and has a shape that spreads after the focal point.
- an ultrasonic transmission beam having a focus set for each of the focus stages A to D may be independently formed and transmitted plural times.
- the beam shape of the ultrasonic transmitting beam or the ultrasonic receiving beam differs in the depth direction of the subject. Therefore, due to the difference in ultrasonic beam intensity in the depth direction, the inherent dynamic range of the ultrasonic beam also differs in the depth direction. For example, at a depth where the ultrasonic beam intensity is large, the inherent dynamic range of the ultrasonic beam is widened. Ultrasonic beam intensity is small! / At the depth, the inherent dynamic range becomes narrow.
- the present embodiment employs a dynamic range calculated based on the beam shape of the ultrasonic beam and the depth of the subject. Then, the dynamic range of the received signal output from the signal processing unit 22 is corrected.
- a second embodiment of the ultrasonic diagnostic apparatus to which the present invention is applied will be described with reference to FIGS.
- This embodiment correlates the beam shape of the ultrasonic beam with the depth of the subject.
- the second embodiment differs from the first embodiment in that the received signal output from the signal processing unit 22 is corrected based on the calculated beam intensity. Therefore, portions that correspond to those of the first embodiment are denoted by the same reference numerals, and differences will be mainly described.
- FIG. 6 is a block diagram showing a configuration of the ultrasonic diagnostic apparatus 2 of the present embodiment.
- the ultrasonic diagnostic apparatus 2 includes a signal strength correction unit 50 instead of the dynamic range correction unit 24 of the first embodiment (for example, FIG. 1).
- the signal intensity correction unit 50 receives and outputs the signal output from the signal processing unit 22 based on the ultrasonic beam calculated in correlation with the beam shape of the ultrasonic beam transmitted and received by the ultrasonic probe 10 and the depth of the subject. Correct the signal strength of the signal.
- the signal strength correction unit 50 has a signal strength calculation unit 52 and a memory 54.
- the signal intensity calculator 52 calculates a beam intensity as correction data correlating to the beam shape of the ultrasonic beam and the depth of the subject (hereinafter, appropriately referred to as a correction beam intensity), and calculates the correction beam intensity.
- the signal strength of the received signal output from the signal processing unit 22 is corrected based on the signal strength.
- the memory 54 stores a beam intensity table in which correction beam intensities are arranged as a function of the depth of the subject (for example, the depth of a sampling point or a focus step).
- FIG. 7 is a flowchart showing the overall processing of the ultrasonic diagnostic apparatus 2 in FIG.
- FIG. 8 is a conceptual diagram for explaining the operation of the signal strength correction unit 50 of FIG.
- the present embodiment includes a correction beam intensity calculation step S200 instead of the correction dynamic range calculation step S100 of the first embodiment, and replaces the received signal correction step S103. And a receiving signal correcting step S203. Therefore, the description will focus on the correction beam intensity calculation step S200 and the received signal correction step S203.
- the correction beam intensities A1 to A4 are calculated by the signal intensity calculator 52.
- the correction beam intensities A1 to A4 are correction data correlated with the beam shape of the ultrasonic beam formed by the ultrasonic probe 10 and the depth of each reflection portion 46-1 to 46-7.
- the beam intensity A1 corresponds to the beam intensity at the focal position of the ultrasonic beam.
- the beam intensity A2 corresponds to the reflection portions 46-4 and 46-5.
- the beam intensity A3 corresponds to the reflection portions 46-2 and 46-7.
- Beam intensity A4 corresponds to the reflection area 46-1, 46-3, 46-6 To do.
- the signal intensity calculation unit 52 calculates the factor correction beam intensity A1-A4 related to the beam shape of the ultrasonic beam.
- the factors here include the frequency of the drive signal supplied from the transmission circuit 12, the number of waves of the drive signal, the coordinates of the focal point of the ultrasonic beam, the number of transducers forming the aperture of the ultrasonic probe 10, and the integer. It is a parameter such as a phase method.
- the phasing method is determined by transmission focus data for delaying the drive signal and reception focus data (for example, focus data stored in the memory 36) for phasing the reception signal.
- the correction beam intensities A1 to A4 are the signal intensities inherent to the ultrasonic beam.
- Such correction beam intensities A1 to A4 are stored in the memory 54 as a beam intensity table after being associated with the sampling point or the depth of the focus stage.
- the correction beam intensity is calculated based on the beam shape of the first ultrasonic beam and the depth of the subject, and the reception corresponding to the first ultrasonic beam is performed.
- the correction beam intensity may be calculated in advance based on the beam shape of the second ultrasonic beam different from the first ultrasonic beam and the depth of the subject.
- the beam intensity A1—A4 for force correction such as actual measurement or simulation may be obtained.
- the received signals S1 to S6 output from the ultrasonic receiving step (S102) are corrected based on the correction beam intensities A1 to A4.
- the signal strength calculation unit 52 reads them from the correction beam strengths A1 to A4 memory 54. Then, among the correction beam intensities A1 to A4, the correction beam intensity A1 is set as the reference intensity.
- the reference beam intensity for correction may be changed as appropriate.
- the relative ratio (for example, A1ZA4) between the correction beam intensity A1 as the reference intensity and the correction beam intensity A4 is obtained.
- the obtained relative ratio corresponds to the amplitude ratio between the beam amplitude at the focal position of the ultrasonic beam and the beam amplitude at the depth of the reflecting portion 46-1.
- Such a relative ratio is corrected Set as a coefficient.
- the signal strength of received signal S1 is corrected by multiplying the signal strength of received signal S1 by a correction coefficient (A1ZA4). Similar processing is performed on the received signals S2 and S6. In short, the received signals S1 to S6 are corrected as received signals B1 to B6 in this step.
- the corrected received signals B1 to B6 are signals that take into account the inherent beam intensity of the ultrasonic beam.
- an ultrasonic image is a reflection part (for example, a reflection part) scattered in the depth direction of the subject.
- the beam intensity of the ultrasonic beam differs in the depth direction in correlation with the beam shape.
- the displayed ultrasonic image includes an error due to the intensity distribution of the transmitted beam in the depth direction.
- the corrected received signals B1-B6 are signals whose signal intensities have been corrected based on the intensity distribution of the ultrasonic beam in the depth direction. That is, the received signals B1 to B6 after the correction become equivalent to the received signals when the beam intensity distribution in the depth direction of the ultrasonic beam is uniform.
- a third embodiment of the ultrasonic diagnostic apparatus to which the present invention is applied will be described with reference to FIGS.
- This embodiment is different from the first embodiment in that the received signal output from the signal processing unit 22 is corrected in the second embodiment as a first-stage correction, and then is corrected in the first embodiment as a second-stage correction.
- This is different from the first and second embodiments. Therefore, the same reference numerals are given to the portions that correspond to the first and second embodiments, and the differences will be mainly described. I will tell.
- FIG. 9 is a block diagram showing a configuration of the ultrasonic diagnostic apparatus 3 of the present embodiment.
- the ultrasonic diagnostic apparatus 3 includes a dynamic range calculator 40 of the first embodiment (for example, FIG. 1) and a signal strength calculator 52 of the second embodiment (for example, FIG. 2). And a correction unit 56 having a memory 58.
- the memory 58 stores a dynamic range table for correction and a beam intensity table for correction.
- the correction unit 56 corrects correction data (for example, correction beam intensity A1 to A4, correction beam intensity A1 to A4) in correlation with the beam shape of the ultrasonic beam transmitted and received by the ultrasonic probe 10 and the depth of the subject.
- correction data for example, correction beam intensity A1 to A4, correction beam intensity A1 to A4
- the dynamic range D1 to D6) is calculated, the received signal output from the signal processing unit 22 is corrected based on the calculated correction data, and the corrected signal is output to the DSC 30.
- FIG. 10 is a flowchart showing the overall processing of the ultrasonic diagnostic apparatus 3 in FIG.
- FIG. 11 is a conceptual diagram for explaining the operation of the correction unit 56 in FIG.
- the correction data calculation process according to the present embodiment includes a correction dynamic range calculation process S100 according to the first embodiment (for example, FIG. 2) and a correction dynamic range calculation process S100 according to the second embodiment (for example, FIG. 7).
- a beam intensity calculation process S 200 is provided.
- the correction dynamic ranges D1 to D6 are calculated and stored in the memory 58 as a dynamic range table
- the correction beam intensities A1 to A4 are calculated and stored in the memory 58 as a signal intensity table. .
- the step of correcting the received signal includes the step of correcting the received signal S203 of the second embodiment and the step of correcting the received signal S103 of the first embodiment.
- the received signals S1 to S6 output from the signal processing unit 22 are subjected to the first-stage correction using the corrected beam intensities A1 to A4, thereby obtaining the received signals B1 to B6. become.
- the received signals B1 to B6 are subjected to the second-stage correction using the corrected dynamic ranges D1 to D6, and thus become the received signals DN1 to DN6 after the second-stage correction.
- the received signals S1-S6 output from the signal processing unit 22 are subjected to first-stage and second-stage corrections that are correlated with the shape of the ultrasonic beam and the depth of the subject.
- the received signals DN1 to DN6 are signals in which the influence of the ultrasonic beam shape and the depth of the subject is reduced by one layer.
- the dynamic range correction unit 24 and the signal intensity correction unit 50 serve as means for correcting the reception signal output from the signal processing unit 22. And at least one of the correction units 56!
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JP2009022656A (ja) * | 2007-07-23 | 2009-02-05 | Aloka Co Ltd | 超音波診断装置 |
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KR102188148B1 (ko) * | 2014-01-17 | 2020-12-07 | 삼성메디슨 주식회사 | 광음향 영상 장치 및 광음향 영상 디스플레이 방법 |
Citations (3)
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JPS612207U (ja) * | 1984-06-08 | 1986-01-08 | 株式会社日立メディコ | 超音波断層装置 |
JPH05245137A (ja) * | 1992-03-06 | 1993-09-24 | Yokogawa Medical Syst Ltd | 超音波診断装置 |
JPH1128210A (ja) * | 1997-05-07 | 1999-02-02 | General Electric Co <Ge> | 超音波散乱物質の三次元イメージング・システムおよび方法 |
Family Cites Families (1)
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JPH02177948A (ja) * | 1988-12-28 | 1990-07-11 | Olympus Optical Co Ltd | 超音波診断装置 |
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---|---|---|---|---|
JPS612207U (ja) * | 1984-06-08 | 1986-01-08 | 株式会社日立メディコ | 超音波断層装置 |
JPH05245137A (ja) * | 1992-03-06 | 1993-09-24 | Yokogawa Medical Syst Ltd | 超音波診断装置 |
JPH1128210A (ja) * | 1997-05-07 | 1999-02-02 | General Electric Co <Ge> | 超音波散乱物質の三次元イメージング・システムおよび方法 |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2009022656A (ja) * | 2007-07-23 | 2009-02-05 | Aloka Co Ltd | 超音波診断装置 |
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