JP5179963B2 - Ultrasonic diagnostic apparatus, operation method thereof, and image processing program - Google Patents

Description

The present invention relates to an ultrasonic diagnostic apparatus for imaging an internal organ or the like by transmitting and receiving ultrasonic waves to generate an ultrasonic image used for diagnosis , and an operation method thereof . Furthermore, the present invention relates to images processing program that is used in such an ultrasonic diagnostic apparatus.

  In the medical field, various imaging techniques have been developed in order to observe and diagnose the inside of a subject. In particular, ultrasonic imaging that acquires internal information of a subject by transmitting and receiving ultrasonic waves enables real-time image observation, and other medical uses such as X-ray photographs and RI (radio isotope) scintillation cameras. Unlike imaging technology, there is no radiation exposure. Therefore, ultrasonic imaging is used as a highly safe imaging technique in a wide range of areas including gynecological system, circulatory system, digestive system, etc. in addition to fetal diagnosis in the obstetrics field.

  In general, in an ultrasound diagnostic apparatus, an ultrasound probe (probe) including a plurality of ultrasound transducers having an ultrasound transmission / reception function is used. Using such an ultrasonic probe, the subject is scanned with an ultrasonic beam formed by combining a plurality of ultrasonic waves, and ultrasonic echoes reflected inside the subject are received and received. By performing the focus processing, image information relating to a structure (for example, a viscera or a diseased tissue) existing in the subject can be obtained based on the intensity of the ultrasonic echo.

  Normally, reception focus processing is performed on the assumption that the sound speed in the subject is constant, but in reality, the sound speed varies depending on the tissue in the subject. A solution to the problem has been proposed.

  As a related technique, Patent Document 1 discloses an ultrasonic diagnostic apparatus aimed at accurately and easily setting an optimum set sound speed value required for electronic beam control. The system control unit of this ultrasonic diagnostic apparatus sets the set sound speed value while superimposing and displaying on the display unit two pre-shooting images obtained by oblique scanning from different directions based on a preset set sound speed value. Are updated sequentially. The delay time calculation unit calculates a delay time for deflecting the ultrasonic beam in the direction using the updated set sound velocity value, and controls the delay times of the transmission unit and the reception unit. The set sound speed value is sequentially updated, and the delay time for beam focusing is set based on the set sound speed value when the deviation between the two images superimposed and displayed on the display unit is minimized. Done. However, such a sound velocity value setting method is difficult to obtain with a device other than a linear probe, and a frame rate is deteriorated because the same region is scanned a plurality of times.

Further, Patent Document 2 discloses an ultra-superimpose aiming to improve the image quality of an ultrasonic tomographic image by making the setting focusing point and the actual focusing point always coincide with each other so as to maximize the effect of the dynamic focusing method. An ultrasonic diagnostic apparatus is disclosed. This ultrasonic imaging apparatus calculates an amount (correlation amount) indicating a correlation between signals in a region (arbitrary depth) designated on a tomographic image among reception signals on adjacent scanning lines, Based on the calculated correlation amount, the degree of convergence of the reception signal (such as the depth position of the reception focus) is controlled. However, since the amount of correlation between signals on adjacent scanning lines is susceptible to noise, it is actually difficult to determine the degree of beam focusing.
Japanese Patent Laying-Open No. 2005-46193 (first page, FIG. 6) Japanese Patent No. 3645347 (6th page, FIG. 1)

Accordingly, in view of the above points, the present invention accurately determines the beam focusing degree without reducing the frame rate in any type of ultrasonic probe, and improves the image quality of the ultrasonic image. It is an object of the present invention to provide an ultrasonic diagnostic apparatus that can be improved and an operating method thereof. Furthermore, the present invention aims at providing a is that images processing program used in such ultrasonic diagnostic apparatus.

In order to solve the above problem, an ultrasonic diagnostic apparatus according to one aspect of the present invention transmits an ultrasonic wave toward a subject according to a plurality of drive signals and receives an ultrasonic echo propagated from the subject. And an ultrasonic probe including a plurality of ultrasonic transducers for outputting a plurality of received signals, a plurality of drive signals being supplied to the plurality of ultrasonic transducers, and a plurality of outputs outputted from the plurality of ultrasonic transducers, respectively. By performing reception focus processing by matching the phases of a plurality of reception signals output from the transmission / reception unit according to a transmission / reception unit that processes the reception signal and a plurality of delay amounts set using at least one phase matching parameter , Reception control that generates sound ray signals along the reception direction of ultrasonic waves and performs envelope detection processing on the generated sound ray signals And an ultrasonic image generation means for generating an image signal representing an ultrasonic image based on the sound ray signal output from the reception control means, and a reception focus process based on the sound ray signal output from the reception control means And at least one phase matching parameter is automatically adjusted according to the determination result, and the subject as a phase matching parameter automatically adjusted in the reception focus process based on the beam convergence degree in the reception focus process And a beam focusing degree determining means for displaying an average value and reliability of the sound speed measured a plurality of times on a display unit .

In addition, an operation method of the ultrasonic diagnostic apparatus according to one aspect of the present invention supplies a plurality of drive signals to a plurality of ultrasonic transducers, transmits ultrasonic waves toward the subject, and propagates from the subject. A method for operating an ultrasonic diagnostic apparatus that performs image processing by processing a plurality of received signals respectively output from a plurality of ultrasonic transducers that have received an ultrasonic echo, wherein the ultrasonic diagnostic apparatus includes at least one phase By performing reception focus processing by matching the phases of a plurality of received signals according to a plurality of delay amounts set using the matching parameters, a sound ray signal along the ultrasonic wave receiving direction is generated, and the generated sound is generated. envelope detection processing facilities to step (a) with respect to the line signal, the ultrasonic diagnostic apparatus, contact the reception focus processing based on the sound ray signal envelope detection processing has been performed Determines that beam focusing degree in accordance with the determination result, and the step (b) to automatically adjust at least one phase-matching parameters, ultrasonic diagnostic apparatus, at least one phase-matching parameters automatically adjusted in step (b) A step (c) of generating an image signal representing an ultrasonic image based on a sound ray signal obtained by using, and an ultrasonic diagnostic apparatus automatically adjusting in a reception focus process based on a beam convergence degree in the reception focus process; A step (d) of measuring the sound velocity in the subject as the phase matching parameter, a plurality of times, and displaying the average value and the reliability of the sound velocity measured a plurality of times on the display unit .

Furthermore, an image processing program according to one aspect of the present invention supplies ultrasonic signals to a subject by supplying a plurality of drive signals to a plurality of ultrasonic transducers, and transmits an ultrasonic echo propagated from the subject. An image processing program used in an ultrasonic diagnostic apparatus for processing a plurality of received signals respectively output from a plurality of ultrasonic transducers that have received a plurality of delay amounts set using at least one phase matching parameter by performing the reception focusing processing by aligning the phases of a plurality of received signals according to generate a sound ray signal along reception direction of the ultrasonic wave, to facilities envelope detection processing on the generated sound ray signals procedure (a), determines the beam focusing degree of reception focus processing based on the sound ray signal envelope detection processing has been performed, determination binding And (b) automatically adjusting at least one phase matching parameter, and representing an ultrasound image based on a sound ray signal obtained using the at least one phase matching parameter automatically adjusted in step (b). Based on the procedure (c) for generating the image signal and the beam focusing degree in the reception focus process, the sound velocity in the subject as a phase matching parameter automatically adjusted in the reception focus process is measured a plurality of times, and is measured a plurality of times. The CPU is caused to execute the procedure (d) for displaying the average value of sound speed and the reliability on the display unit .

  According to the present invention, the degree of beam convergence in the reception focus processing is determined, and at least one phase matching parameter is automatically adjusted according to the determination result. Therefore, the frame rate can be set even when any type of ultrasonic probe is used. The accuracy of the ultrasonic image can be improved by accurately determining the beam focusing degree without deteriorating.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of the ultrasonic diagnostic apparatus according to the first embodiment of the present invention. The ultrasonic diagnostic apparatus includes an ultrasonic probe 10, a scanning control unit 11, a transmission delay pattern storage unit 12, a transmission control unit 13, a drive signal generation unit 14, a reception signal processing unit 21, and a reception. The delay pattern storage unit 22, the reception control unit 23, the B-mode image generation unit 30, the D / A converter 34, the display unit 35, the beam focusing degree determination unit 40, the console 51, and the control unit 52. And a storage unit 53.

  The ultrasonic probe 10 may be an external probe such as a linear scan method, a convex scan method, or a sector scan method, or may be an ultrasonic endoscope probe such as an electronic radial scan method or a mechanical radial scan method. The ultrasonic probe 10 includes a plurality of ultrasonic transducers 10a constituting a one-dimensional or two-dimensional transducer array. These ultrasonic transducers 10a transmit ultrasonic waves based on the applied drive signals, receive propagating ultrasonic echoes, and output reception signals.

  Each ultrasonic transducer is, for example, a piezoelectric ceramic represented by PZT (Pb (lead) zirconate titanate) or a polymer piezoelectric element represented by PVDF (polyvinylidene difluoride). It is constituted by a vibrator in which electrodes are formed at both ends of a piezoelectric material (piezoelectric body). When a pulsed or continuous wave voltage is applied to the electrodes of such a vibrator, the piezoelectric body expands and contracts. By this expansion and contraction, pulsed or continuous wave ultrasonic waves are generated from the respective vibrators, and an ultrasonic beam is formed by combining the ultrasonic waves. Each vibrator expands and contracts by receiving propagating ultrasonic waves and generates an electrical signal. These electrical signals are output as ultrasonic reception signals.

  The scanning control unit 11 sequentially sets the transmission direction of the ultrasonic beam and the reception direction of the ultrasonic echo. The scanning of the subject by the ultrasonic beam may be performed electronically or mechanically. The transmission delay pattern storage unit 12 stores a plurality of transmission delay patterns used when forming an ultrasonic beam. The transmission control unit 13 selects one pattern from a plurality of delay patterns stored in the transmission delay pattern storage unit 12 according to the transmission direction set in the scanning control unit 11, and based on the pattern The delay times given to the drive signals of the plurality of ultrasonic transducers 10a are set. Alternatively, the transmission control unit 13 may set the delay time so that ultrasonic waves transmitted at a time from the plurality of ultrasonic transducers 10a reach the entire imaging region of the subject.

  For example, the drive signal generator 14 includes a plurality of pulsars corresponding to the plurality of ultrasonic transducers 10a. The drive signal generation unit 14 transmits the plurality of drive signals to the ultrasonic probe so that the ultrasonic waves transmitted from the plurality of ultrasonic transducers 10a form an ultrasonic beam according to the delay time set by the transmission control unit 13. 10 or a plurality of drive signals are supplied to the ultrasound probe 10 so that the ultrasonic waves transmitted from the plurality of ultrasound transducers 10a at a time reach the entire imaging region of the subject.

  The reception signal processing unit 21 includes a plurality of amplifiers (preamplifiers) 21a and a plurality of A / D converters 21b corresponding to the plurality of ultrasonic transducers 10a. The reception signal output from the ultrasonic transducer 10a is amplified by the amplifier 21a, and the analog reception signal output from the amplifier 21a is converted into a digital reception signal by the A / D converter 21b. The A / D converter 21 b outputs a digital reception signal to the reception control unit 23.

  The reception delay pattern storage unit 22 stores a plurality of reception delay patterns used when receiving focus processing is performed on a plurality of reception signals output from the plurality of ultrasonic transducers 10a. The reception control unit 23 selects one pattern from a plurality of reception delay patterns stored in the reception delay pattern storage unit 22 based on the reception direction set in the scanning control unit 11, and the pattern, Based on at least one phase matching parameter, reception focus processing is performed by adding a delay to a plurality of reception signals. By this reception focus processing, a sound ray signal in which the focus of the ultrasonic echo is narrowed is generated. Further, the reception control unit 23 performs envelope detection processing on the formed sound ray signal.

  Here, the at least one phase matching parameter includes information regarding the speed of sound in the subject. In general, 1530 m / s or 1540 m / s is used as the sound velocity value C0 in the human body, but actually, the sound velocity value varies depending on tissues in the human body. Therefore, by setting the sound velocity value Ci in the subject based on the phase matching parameter and multiplying the delay amount D0 (j) in the reception delay pattern by (C0 / Ci), a plurality of delay amounts D1 (j) = ( C0 / Ci) · D0 (j) is set (j = 1, 2,..., L). L is the number of ultrasonic transducers used.

  Alternatively, the at least one phase matching parameter may include information on the delay amount calculated based on the sound velocity in the subject, for example, a coefficient that multiplies the delay amount. By setting the coefficient Ki based on the phase matching parameter and multiplying the delay amount D0 (j) in the reception delay pattern by the coefficient Ki, a plurality of delay amounts D1 (j) = Ki · D0 (j) are set ( j = 1, 2,..., L).

  The B-mode image generation unit 30 generates a B-mode image signal that is tomographic image information related to the tissue in the subject based on the sound ray signal output from the reception control unit 23. For this purpose, the B-mode image generation unit 30 includes a sound ray signal storage unit 31, an STC (sensitivity time control) unit 32, and a DSC (digital scan converter) 33.

  The sound ray signal storage unit 31 includes a memory or the like, and temporarily stores a sound ray signal (sound ray data) output from the reception control unit 23. The STC unit 32 corrects attenuation with respect to the sound ray signal read from the sound ray signal storage unit 31 according to the depth of the reflection position of the ultrasonic wave. The DSC 33 converts (raster conversion) the sound ray signal corrected by the STC unit 32 into an image signal in accordance with a normal television signal scanning method, and performs necessary image processing such as gradation processing to thereby obtain a B-mode image. Generate a signal.

  The D / A converter 34 converts the digital image signal output from the B-mode image generation unit 30 into an analog image signal. The display unit 35 includes a display device such as a CRT or LCD, for example, and displays an ultrasonic image based on an analog image signal.

  In the autofocus (AF) mode, the control unit 52 determines the beam convergence degree and / or adjusts the beam convergence degree in parallel with the generation of the B-mode image signal by the B-mode image generation unit 30. And / or the scanning control part 11 is controlled. The beam focusing degree determination unit 40 determines the beam focusing degree in the reception focus process based on the sound ray signal output from the reception control unit 23, and automatically adjusts at least one phase matching parameter according to the determination result.

  In addition, in the sound speed measurement mode, the control unit 52 is configured to measure the sound velocity in the subject in parallel with the generation of the B-mode image signal by the B-mode image generation unit 30 and / or the beam focusing degree determination unit 40 and / or The scanning control unit 11 is controlled. The beam convergence determination unit 40 measures the sound speed in the subject N times based on the beam convergence degree in the reception focus process (N is an integer of 2 or more), and calculates the average value and reliability of the sound speed measured N times. It is displayed on the display unit 35.

  The beam convergence determination unit 40 includes a sound ray signal storage unit 41, a band limited image generation unit 42, and a focus determination unit 43. The sound ray signal storage unit 41 includes a memory or the like, and temporarily stores a sound ray signal (sound ray data) output from the reception control unit 23. The band limited image generation unit 42 generates a band limited image signal by limiting the frequency band of the sound ray signal read from the sound ray signal storage unit 41.

  In the AF mode, the focus determination unit 43 adjusts at least one phase matching parameter when it is determined that the focus shift is based on the band limited image signal generated by the band limited image generation unit 42. In the adjustment of the phase matching parameter, the focus determination unit 43 limits the band of a plurality of consecutive frames while changing at least one phase matching parameter used in the reception focus process performed by the reception control unit 23 to determine the focus. A focus determination value is calculated for the image signal, and a new phase matching parameter is set based on the calculated plurality of focus determination values. The set new phase matching parameter is used in a reception focus process performed by the reception control unit 23 in order to generate an ultrasonic image. Thereby, in the B mode image signal generated in the B mode image generation unit 30, the image quality of the ultrasonic image is improved.

  In addition, the focus determination unit 43 focuses on the band-limited image signals of a plurality of consecutive frames while changing the sound speed value used in the reception focus process performed by the reception control unit 23 to determine the focus in the sound speed measurement mode. A determination value is calculated, and an optimum sound speed value is obtained based on the calculated plurality of focus determination values. Thereby, the speed of sound in the subject is measured. In this way, the beam convergence determination unit 40 measures the sound speed in the subject N times, and causes the display unit 35 to display the average value and reliability of the sound speed measured N times. As a result, a material for determining whether or not the measurement result of the sound speed can be taken into the diagnosis is shown, which leads to improvement of the diagnostic ability.

  The control unit 52 controls the scanning control unit 11, the B-mode image generation unit 30, the beam focusing degree determination unit 40, and the like according to the operation of the operator using the console 51. For example, the control unit 52 can control each unit and set a freeze mode (a mode in which the same screen is repeatedly displayed based on stored data). In addition, the console 51 includes switching means (such as a switch or a switch button) 51a used for turning on / off automatic adjustment of the phase matching parameter in the AF mode, and a sound velocity measurement mode on (set) / off ( Switching means 51b used for canceling) and measurement number setting means (such as a numeric keypad) 51c used for setting the number N of times of measuring the speed of sound in the subject are provided.

  In the present embodiment, the scanning control unit 11, the transmission control unit 13, the reception control unit 23, the STC 32, the DSC 33, the band limited image generation unit 42, the focus determination unit 43, and the control unit 52 include a CPU and software (program). However, these may be constituted by a digital circuit or an analog circuit. Software (program) is stored in the storage unit 53. As a recording medium in the storage unit 53, a flexible disk, MO, MT, RAM, CD-ROM, DVD-ROM, or the like can be used in addition to the built-in hard disk.

  Next, the beam focusing degree determination unit 40 shown in FIG. 1 will be described in detail with reference to FIGS. The band-limited image generation unit 42 of the beam focusing degree determination unit 40 performs a high-pass filter process or a band-pass filter process on the sound ray signal read from the sound ray signal storage unit 41, thereby obtaining a band-limited image signal. Generate. At that time, the frequency band of the band limited image signal may be set according to the frequency of the ultrasonic wave to be transmitted and / or the depth of the focus formed in the subject.

  2 is a diagram illustrating a first configuration example of the band limited image generation unit illustrated in FIG. 1, and FIG. 3 illustrates an image represented by the image data generated by the band limited image generation unit illustrated in FIG. It is a figure which shows a spatial frequency band.

As shown in FIG. 2, the band limited image generation unit 42 a according to the first configuration example includes a downsampling unit 61, an upsampling unit 62, and a subtraction unit 63. The sound ray signal (original data) I _{ORG for} one frame read from the sound ray signal storage unit 41 is subjected to filtering processing such as thinning-out processing and Nyquist filter processing by the downsampling unit 61. Thereby, down-sampling data _IDWN having a small data size is generated.

Next, the down-sampling data I _DWN is subjected to a filtering process such as a process of inserting “0” value data and a smoothing filter process in the up-sampling unit 62. Thereby, up-sampling data (low-resolution image signal) I _LOW having the same data size as the original sound ray data I _ORG is obtained. As shown in FIG. 3, the upsampling data I _LOW has a spatial frequency component lower than the cutoff frequency f _C and represents a blurred image with a low resolution.

Next, the subtracting unit 63 performs processing for subtracting the up-sampling data I _LOW from the original data I _{ORG as} shown in the following equation (1). Thereby, subband data I _SUB is obtained.
I _SUB = | I _ORG -I _LOW │ (1)

As shown in FIG. 3, the subband data I _SUB has a higher spatial frequency component than the cut-off frequency f _C. In this way, the band limited image generation unit 42a generates a band limited image signal by performing high-pass filter processing on the original data I _ORG .

The control unit 52 sets the cutoff frequency f _C according to the frequency of the transmitted ultrasonic wave and / or the depth of the focal point formed in the subject. For example, the control unit 52 increases the cutoff frequency f _C if the ultrasonic frequency is high, and decreases the cutoff frequency f _C if the ultrasonic frequency is low. The control unit 52 increases the cutoff frequency f _C when the focal depth is shallow, and decreases the cutoff frequency f _C when the focal depth is deep.

  4 is a diagram illustrating a second configuration example of the band limited image generation unit illustrated in FIG. 1, and FIG. 5 illustrates an image represented by the image data generated by the band limited image generation unit illustrated in FIG. It is a figure which shows a spatial frequency band.

As shown in FIG. 4, the band limited image generation unit 42b according to the second configuration example includes downsampling units 71 and 74, upsampling units 72 and 75, and subtraction units 73, 76, and 77. . The sound ray signal (original data) I _{ORG for} one frame read out from the sound ray signal storage unit 41 is subjected to filter processing such as thinning-out processing and Nyquist filter processing by the downsampling unit 71. Thereby, downsampling data I _DWN1 having a small data size is generated.

Next, the downsampling data I _DWN1 is subjected to filtering processing such as processing for inserting data of “0” value and smoothing filtering processing in the upsampling unit 72. Thereby, up-sampling data (low-resolution image signal) I _LOW having the same data size as the original sound ray data I _ORG is obtained. As shown in FIG. 5, the upsampling data I _LOW has a spatial frequency component lower than the cutoff frequency f _C1 (blurred image resolution 1).

Next, the subtracting unit 73 performs processing for subtracting the up-sampling data I _LOW from the original data I _{ORG as} shown in the following equation (2). Thereby, subband data _ISUB1 is obtained.
I _SUB1 = | I _ORG -I _LOW | (2)

As shown in FIG. 5, the subband data I _SUB1 has a higher spatial frequency component than the cutoff frequency f _C1 . The subband data I _SUB1 is subjected to filter processing such as thinning processing and Nyquist filter processing by the downsampling unit 74. Thereby, down-sampled data I _DWN2 having a small data size is generated.

Next, the down-sampling data I _DWN2 is subjected to filtering processing such as processing for inserting data of “0” value and smoothing filtering processing in the up-sampling unit 75. Thereby, up-sampling data I _MID1 having the same data size as the subband data I _SUB1 is obtained.

The up-sampling data I _MID1 may be used as the band limited image signal. Further, the sub-sampling unit 76 subtracts the up-sampling data I _MID1 from the subband data I _SUB1 as shown in Expression (3). Subband data I _SUB2 and subtracting unit 77 subtracts subband data I _SUB2 from subband data I _SUB1 to generate subband data I _MID2 as shown in equation (4). It may be a restricted image signal.
I _SUB2 = | I _SUB1 -I _MID1 │ (3)
I _MID2 = | I _SUB1 −I _SUB2 | (4)

As shown in FIG. 5, the up-sampling data I _MID1 (or subband data I _MID2 ) is higher than the cutoff frequency f _C1 (blur image resolution 1) and lower than the cutoff frequency f _C2 (blur image resolution 2). It has a spatial frequency component. In this way, the band limited image generation unit 42a generates a band limited image by performing the band pass filter process on the original data I _ORG .

The control unit 52 sets the cut-off frequencies f _C1 and f _C2 according to the frequency of the transmitted ultrasonic wave and / or the depth of the focus formed in the subject. For example, the control unit 52 increases the cutoff frequencies f _C1 and f _C2 when the ultrasonic frequency is high, and decreases the cutoff frequencies f _C1 and f _C2 when the ultrasonic frequency is low. The control unit 52 increases the cutoff frequencies f _C1 and f _C2 when the depth of focus is shallow, and decreases the cutoff frequencies f _C1 and f _C2 when the depth of focus is deep.

The focus determination unit 43 illustrated in FIG. 1 calculates a focus determination value based on the average value or energy value of the band limited image signal generated by the band limited image generation unit 42. For example, assuming that the band limited image signal in one frame is I _SUB (p) (pixel number p = 1, 2,..., M), the focus determination unit 43 uses the band limited image signal I as the focus determination value. average _{I AVE = ΣI SUB (p)} / M of _SUB (p), or the energy value of the band-limited image signal _{I SUB} (p) (image energy _amount) is calculated ^{_{I ENG = ΣI SUB (p)}} 2.

  The operator can set an image region used for calculation of the focus determination value by the focus determination unit 43 by operating the console 51. For example, it is possible to set from the system setting using coordinates and a trackball, or to select a region such as a central portion, a shallow portion, and a deep portion from the system setting. Alternatively, the image area used for calculation of the focus determination value by the focus determination unit 43 may be automatically selected based on the average luminance of a plurality of areas divided in advance. For example, the region having the highest average luminance is selected, or the region having the average luminance closest to the median value is selected.

  The focus determination unit 43 determines that the focus is achieved when the focus determination value is larger than the threshold value, and determines that the focus is shifted when the focus determination value is equal to or less than the threshold value. Further, when the focus determination unit 43 determines that the focus is shifted, the focus determination value is calculated for the band limited image signals of a plurality of consecutive frames while changing at least one phase matching parameter. Based on the plurality of focus determination values, at least one phase matching parameter is adjusted and / or an optimum sound speed value is obtained.

  FIG. 6 is a diagram for explaining the operation of the ultrasonic diagnostic apparatus shown in FIG. Here, the speed of sound in the subject is used as the phase matching parameter. As shown in FIG. 6, a reception signal is generated by transmitting and receiving ultrasonic waves in each frame period. In the first frame period, the reception control unit 23 generates a sound ray signal by performing reception focus processing according to a plurality of delay amounts set using the initial value C0 of the sound velocity in the subject, and the generated sound By performing envelope detection processing on the line signals, the sound line signals are collected and stored in the sound line signal storage units 31 and 41.

  The B-mode image generation unit 30 generates the B-mode image signal based on the sound ray signal collected in the first frame period, so that the ultrasonic image is displayed in the second frame period. Further, the band limited image generation unit 42 generates the band limited image signal based on the sound ray signal collected in the first frame period, so that the focus determination unit 43 sets the focus determination value in the second frame period. calculate. The focus determination unit 43 determines that the focus is achieved when the focus determination value is larger than the threshold value, and determines that the focus is shifted when the focus determination value is equal to or less than the threshold value.

  Further, when the focus determination unit 43 determines that the focus is shifted in the AF mode, or in the sound speed measurement mode, the sound speed value is set to C0, C1,... In a period corresponding to a predetermined number of frames. , Cn. The reception control unit 23 stores the sound ray signals collected by performing the reception focus processing for generating an ultrasonic image using the initial value C0 of the sound velocity in the sound ray signal storage unit 31, and also by the focus determination unit 43. The sound ray signals collected by performing the reception focus process using the set sound velocity values C0, C1,..., Cn are stored in the sound ray signal storage unit 41.

The focus determination unit 43 calculates a plurality of focus determination values from a band limited image of a predetermined number of frames, and obtains an optimal sound speed value from among the sound speed values C0, C1,. . For example, the sound speed value at which the focus determination value is maximized is set as the new sound speed value C _NEW . In the next frame period, the new sound velocity value C _NEW is used for the reception control unit 23 to perform reception focus processing for generating an ultrasonic image. Such an automatic adjustment operation of the phase matching parameter may be performed while a moving image is being captured, or may be performed while the movement of the ultrasonic probe 10 is stopped.

FIG. 7 is a flowchart showing the operation of the focus determination unit shown in FIG.
In step S11, the focus determination unit 43 calculates a focus determination value from the band limited image signal generated based on the sound ray signal collected in the first frame period. In step S12, the focus determination unit 43 determines whether or not the calculated focus determination value is greater than a threshold value. When the focus determination value is larger than the threshold value, the focus determination process at steps S11 to S12 is repeated. When the focus determination value is equal to or less than the threshold value, the focus adjustment process after step S13 is performed.

In step S13, the focus determination unit 43 calculates a plurality of focus determination values from the band limited images of a predetermined number of frames corresponding to the sound speed values C0, C1,. In step S <b> 14, the focus determination unit 43 obtains an optimum sound speed value that maximizes the focus determination value, and sets the optimum sound speed value as a new sound speed value C _NEW .

In the sound speed measurement mode, the sound speed is measured N times by obtaining the optimum sound speed value as described above. Furthermore, the focus determination unit 43 calculates the average value and reliability of the sound speed measured N times. The reliability of the sound speed is calculated using, for example, the dispersion or standard deviation of the sound speed measured N times. Here, assuming that the average value of the sound speeds C (i) (i = 1, 2,..., N) measured N times is C _AVE , the variance σ ² is expressed by the following equation (5), and the standard The deviation σ is expressed by the following equation (6). The greater the variation in sound speed, the smaller the reliability of sound speed, and the smaller the variation in sound speed, the greater the reliability of sound speed.

Next, a second embodiment of the present invention will be described.
FIG. 8 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus according to the second embodiment of the present invention. The ultrasonic diagnostic apparatus according to the second embodiment has a beam focusing degree determination unit 44 instead of the beam focusing degree determination part 40 in the ultrasonic diagnostic apparatus according to the first embodiment shown in FIG. . In addition to the sound ray signal storage unit 41, the band-limited image generation unit 42, and the focus determination unit 43 described in the first embodiment, the beam convergence determination unit 44 moves the ultrasonic probe 10. It further includes a probe stop determination unit 45 that determines whether the probe is stopped or stopped. The other points are the same as in the first embodiment.

  The probe stop determination unit 45 obtains the inter-frame difference of the band limited image signal (for example, the low resolution image signal) generated by the band limited image generation unit 42, so that the ultrasonic probe 10 moves. Whether it is stopped or stopped. While the probe stop determination unit 45 determines that the ultrasonic probe 10 is stopped, the focus determination unit 43 determines the beam convergence degree in the reception focus process, and at least according to the determination result, One phase matching parameter is automatically adjusted.

  FIG. 9 is a diagram illustrating a configuration example of the band-limited image generation unit and the probe stop determination unit illustrated in FIG. The configuration of the band-limited image generation unit is the same as that shown in FIG. The probe stop determination unit 45 includes a frame memory 64, a subtraction unit 65, and a determination unit 66.

Upsampling data (low resolution image signal) I _LOW obtained by the upsampling unit 62 of the band limited image generation unit 42 a is stored in the frame memory 64 and input to the subtraction unit 65. The subtracting unit 65 calculates the difference (probe stop determination value) between the upsampling data I _LOW input from the upsampling unit 62 and the upsampling data I _LOW stored in the frame memory 64 one frame before. To do. The determination unit 66 determines that the ultrasonic probe 10 is moving when the probe stop determination value is larger than a predetermined value, and when the probe stop determination value is equal to or less than the predetermined value. It is determined that the ultrasonic probe 10 is stopped.

FIG. 10 is a flowchart showing operations of the probe stop determination unit and the focus determination unit shown in FIG.
In step S21, the probe stop determination unit 45 calculates a probe stop determination value from the band limited image signal generated by the band limited image generation unit. In step S22, the probe stop determination unit 45 determines whether the ultrasonic probe 10 is moving or stopped. If the probe stop determination value is larger than the predetermined value, the probe stop determination process in steps S21 to S22 is repeated. If the probe stop determination value is equal to or smaller than the predetermined value, step S23 is executed. Subsequent focus determination processing is performed.

  In step S23, the focus determination unit 43 calculates a focus determination value from the band limited image signal generated based on the sound ray signal. In step S24, the focus determination unit 43 determines whether or not the calculated focus determination value is greater than a threshold value. If the focus determination value is larger than the threshold value, the focus determination process in steps S23 to S24 is repeated. If the focus determination value is equal to or less than the threshold value, the focus adjustment process in step S25 and subsequent steps is performed.

In step S25, the focus determination unit 43 calculates a plurality of focus determination values from a band limited image of a predetermined number of frames corresponding to the sound velocity values C0, C1,. In step S26, an optimum sound speed value at which the focus determination value is maximized is obtained, and the optimum sound speed value is set as a new sound speed value _CNEW .

  In the sound speed measurement mode, the sound speed is measured N times by obtaining the optimum sound speed value as described above. Furthermore, the focus determination unit 43 calculates the average value and reliability of the sound speed measured N times. The calculated average value and reliability of the sound speed are displayed on the display unit 35 (FIG. 8).

  INDUSTRIAL APPLICABILITY The present invention can be used in an ultrasonic diagnostic apparatus that performs imaging of an organ or the like in a living body by transmitting and receiving ultrasonic waves and generates an ultrasonic image used for diagnosis.

1 is a block diagram illustrating a configuration of an ultrasonic diagnostic apparatus according to a first embodiment of the present invention. It is a figure which shows the 1st structural example of the band-limited image generation part shown in FIG. It is a figure which shows the spatial frequency band of the image represented by the image data produced | generated by the zone | band limited image generation part shown in FIG. It is a figure which shows the 2nd structural example of the band-limited image generation part shown in FIG. It is a figure which shows the spatial frequency band of the image represented by the image data produced | generated by the zone | band limited image generation part shown in FIG. It is a figure for demonstrating operation | movement of the ultrasound diagnosing device shown in FIG. It is a flowchart which shows operation | movement of the focus determination part shown in FIG. It is a block diagram which shows the structure of the ultrasonic diagnosing device which concerns on the 2nd Embodiment of this invention. It is a figure which shows the structural example of the band-limited image generation part and probe stop determination part which are shown in FIG. It is a flowchart which shows operation | movement of the probe stop determination part and focus determination part which are shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ultrasonic probe 10a Ultrasonic transducer 11 Scan control part 12 Transmission delay pattern memory | storage part 13 Transmission control part 14 Drive signal generation part 21 Reception signal processing part 21a Amplifier 21b A / D converter 22 Reception delay pattern memory | storage part 23 Reception Control unit 30 B-mode image generation unit 31 Sound ray signal storage unit 32 STC unit 33 DSC
34 D / A converter 35 Display unit 40, 44 Beam convergence determination unit 41 Sound ray signal storage unit 42, 42a, 42b Band-limited image generation unit 43 Focus determination unit 45 Probe stop determination unit 51 Console 51a Switching means 52 Control unit 53 Storage unit 61, 71, 74 Downsampling unit 62, 72, 75 Upsampling unit 63, 65, 73, 76, 77 Subtraction unit 64 Frame memory 66 Judgment unit

Claims (16)

An ultrasonic probe including a plurality of ultrasonic transducers that transmit ultrasonic waves to a subject according to a plurality of drive signals and output a plurality of received signals by receiving ultrasonic echoes propagated from the subject; ,
A transmission / reception unit for supplying a plurality of drive signals to the plurality of ultrasonic transducers and processing a plurality of reception signals respectively output from the plurality of ultrasonic transducers;
In accordance with a plurality of delay amounts set by using at least one phase matching parameter, the reception focus processing is performed by matching the phases of the plurality of reception signals output from the transmission / reception unit, thereby performing along the ultrasonic wave reception direction. Receiving control means for generating a sound ray signal and performing envelope detection processing on the generated sound ray signal;
Ultrasonic image generating means for generating an image signal representing an ultrasonic image based on a sound ray signal output from the reception control means;
Based on the sound ray signal output from the reception control means, the beam focusing degree in the reception focus process is determined, and the at least one phase matching parameter is automatically adjusted according to the determination result, and the beam focusing degree in the reception focus process is adjusted. Based on the beam focusing degree determination means for measuring the sound speed in the subject as a phase matching parameter automatically adjusted in the reception focus processing a plurality of times and displaying the average value and reliability of the sound speed measured a plurality of times on the display unit When,
An ultrasonic diagnostic apparatus comprising:   The ultrasonic diagnostic apparatus according to claim 1, wherein the at least one phase matching parameter includes information related to a sound speed in the subject or information related to a delay amount calculated based on the sound speed in the subject. The beam focusing degree determining means is
Band-limited image generation means for generating a band-limited image signal by limiting the frequency band of the sound ray signal output from the reception control means;
A focus that calculates a focus determination value based on the band limited image signal generated by the band limited image generation unit, and adjusts the at least one phase matching parameter when it is determined that the focus shift is based on the focus determination value. A determination means;
The ultrasonic diagnostic apparatus according to claim 1, comprising:   The ultrasonic diagnosis according to claim 3, wherein the band-limited image generation unit generates a band-limited image signal by performing high-pass filter processing or band-pass filter processing on the sound ray signal output from the reception control unit. apparatus.   The apparatus further includes a control unit that sets the frequency band of the band-limited image signal generated by the band-limited image generation unit according to the frequency of the ultrasonic wave to be transmitted and / or the depth of the focal point formed in the subject. The ultrasonic diagnostic apparatus according to claim 3 or 4.   The focus determination unit calculates a focus determination value based on an average value or an energy value of the band limited image signal generated by the band limited image generation unit, and determines a focus shift when the focus determination value is equal to or less than a threshold value. The ultrasonic diagnostic apparatus according to claim 3.   When the focus determination unit determines that there is a focus shift based on the band limited image signal generated by the band limited image generation unit, the band limitation of a plurality of consecutive frames is performed while changing the at least one phase matching parameter. The ultrasonic diagnostic apparatus according to claim 3, wherein a focus determination value is calculated for the image signal, and the at least one phase matching parameter is adjusted based on the calculated plurality of focus determination values.   The ultrasonic diagnostic apparatus according to claim 3, further comprising an operation unit configured to set an image region used for calculation of a focus determination value by the focus determination unit.   9. The beam focusing degree determination unit determines a beam focusing degree in reception focus processing and automatically adjusts the at least one phase matching parameter according to a determination result while a moving image is being photographed. The ultrasonic diagnostic apparatus of any one of Claims. Further comprising probe movement determining means for determining whether the ultrasonic probe is moving or stopped,
While the probe movement determination means determines that the ultrasonic probe is stopped, the beam convergence determination means determines the beam convergence in the reception focus process, and according to the determination result. Automatically adjusting the at least one phase matching parameter;
The ultrasonic diagnostic apparatus of any one of Claims 1-8.   The ultrasonic probe is calculated by calculating the inter-frame difference of the low-resolution image signal generated by the probe movement determination unit limiting the resolution of the sound ray signal output from the reception control unit. The ultrasonic diagnostic apparatus according to claim 10, wherein the ultrasonic diagnostic apparatus determines whether the robot is moving or stopped.   The ultrasonic diagnostic apparatus according to claim 1, further comprising switching means used to turn on / off automatic adjustment of a phase matching parameter by the beam focusing degree judging means. Number of times to measure the sound speed in the subject is can be set using the setting means, the ultrasonic diagnostic apparatus according to any one of claims 1 to 12. 14. The ultra-high speed according to claim 1, wherein the beam focusing degree determination unit calculates the reliability of the sound speed displayed on the display unit using a dispersion or standard deviation of the sound speed measured a plurality of times. Ultrasonic diagnostic equipment. A plurality of drive signals are respectively supplied to the plurality of ultrasonic transducers to transmit ultrasonic waves toward the subject, and a plurality of outputs are output from the plurality of ultrasonic transducers that have received the ultrasonic echoes propagated from the subject. a processes the received signal method of operating an ultrasonic diagnostic apparatus which performs image processing,
The ultrasonic diagnostic apparatus performs reception focus processing by aligning the phases of a plurality of reception signals according to a plurality of delay amounts set using at least one phase matching parameter, so that it follows the ultrasonic wave reception direction. generates a sound ray signal, facilities to step envelope detection processing on the generated sound ray signal (a),
The ultrasonic diagnostic apparatus determines a beam focusing degree in the reception focus process based on the sound ray signal subjected to the envelope detection process, and automatically adjusts the at least one phase matching parameter according to the determination result (b) )When,
A step (c) in which the ultrasonic diagnostic apparatus generates an image signal representing an ultrasonic image based on the sound ray signal obtained by using at least one phase matching parameter automatically adjusted in the step (b);
The ultrasonic diagnostic apparatus measures the sound velocity in the subject as a phase matching parameter automatically adjusted in the reception focus processing based on the beam focusing degree in the reception focus processing, and averages the sound speeds measured multiple times Displaying the value and the reliability on the display unit (d);
A method for operating an ultrasonic diagnostic apparatus comprising: A plurality of drive signals are respectively supplied to the plurality of ultrasonic transducers to transmit ultrasonic waves toward the subject, and a plurality of outputs are output from the plurality of ultrasonic transducers that have received the ultrasonic echoes propagated from the subject. An image processing program used in an ultrasonic diagnostic apparatus for processing a received signal of
By performing reception focus processing by matching the phases of a plurality of received signals according to a plurality of delay amounts set using at least one phase matching parameter, a sound ray signal along the ultrasonic wave receiving direction is generated, facilities to procedure envelope detection processing on the generated sound ray signal (a),
A step (b) of determining a beam convergence degree in the reception focus processing based on the sound ray signal subjected to the envelope detection processing, and automatically adjusting the at least one phase matching parameter according to the determination result;
A step (c) for generating an image signal representing an ultrasonic image based on the sound ray signal obtained by using at least one phase matching parameter automatically adjusted in the step (b);
Based on the beam focusing degree in the reception focus processing, the sound velocity in the subject is measured a plurality of times as the phase matching parameter automatically adjusted in the reception focus processing, and the average value and reliability of the sound velocity measured a plurality of times are displayed. The procedure (d) to be displayed on
An image processing program for causing a CPU to execute

Images