JPH078492A - Ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To reduce the sensitivity deviation among plural rasters by receiving. at the same time for once transmission and to suppress the deterioration of picture by changing at least one of the transmission direction or transmission beam shape based on the comparison result of the signal intensity of the same depth of each reception direction. CONSTITUTION:A control circuit 8 accepts the power P of each raster received, at the same time in different reception directions consisting of color flow mapping processing systems 5-1 1 to 5-N. Based on the comparison result between powers with the same depth of each raster, the delay amount of respective transmission delay elements 2B-1 to 2B-M are controlled through a transmission delay control circuit 2E and the transmission direction is changed. The sensitivity deviation between rasters received at the same time can uniformly be corrected by changing the opening width by selecting vibrators 1-1 to 1-M which are driven through a pulser voltage control circuit 2D.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus having a so-called parallel simultaneous reception function for simultaneously receiving reflected waves from a plurality of different directions in response to one ultrasonic wave transmission.

[0002]

2. Description of the Related Art An ultrasonic diagnostic apparatus emits an ultrasonic pulse into a living body and receives a reflected wave reflected from a boundary surface of tissues having different specific acoustic impedances (the product of the density of both media and the sound velocity). After that, it is processed to obtain an ultrasonic tomographic image. There is no radiation damage like the X-ray diagnostic method, and a tomographic image of soft tissue can be observed without using a contrast agent, which is clinically useful. It is a device. Moreover, real-time performance is improved due to the progress of various technologies represented by electronic scanning technology,
Motion measurement has become easier.

By the way, since the time required for the reciprocation of ultrasonic waves is fixed depending on the depth of field, the number of pulses per second is limited accordingly. Therefore, under the condition that the viewing angle and the viewing depth are constant, if the number of scanning lines (hereinafter referred to as “raster”) is increased to improve the spatial resolution in the azimuth direction, the frame rate decreases. As a result, there arises a problem that the time resolution is lowered.

In the case of color flow mapping, the number of repetitions of ultrasonic wave transmission / reception in the same direction is increased to increase the number of data at the same position, thereby improving the clutter component removal accuracy and the measurement accuracy. You can However, in this case, under the condition that the number of rasters is constant, the frame rate decreases and the real-time performance deteriorates as the number of data increases.

As described above, the limitation of the number of pulses imposes the choice of which of spatial resolution and temporal resolution has priority, and in the case of color flow mapping, which of measurement accuracy and real-time performance has priority. Press for choice.

The parallel simultaneous reception method was developed to solve such a problem, and it receives reflected waves from a plurality of different directions at the same time for one ultrasonic wave transmission,
By processing the reflected waves in each direction in parallel, the processing speed is improved and good real-time performance is achieved while maintaining a constant spatial resolution or measurement accuracy.

However, the sound field distribution of the transmission beam is not uniform, so that there is a problem that unevenness in sensitivity occurs between a plurality of rasters obtained by simultaneous reception and image deterioration occurs.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to address the above-mentioned circumstances, and an object thereof is to obtain a plurality of signals obtained by simultaneously receiving reception signals in a plurality of directions for one transmission. It is an object of the present invention to provide an ultrasonic diagnostic apparatus capable of reducing sensitivity unevenness between rasters and suppressing deterioration of image quality.

[0009]

An ultrasonic diagnostic apparatus according to the present invention simultaneously receives reflected waves from a plurality of different receiving directions in response to one transmission of ultrasonic waves and forms an image based on the received signals. In the generated ultrasonic diagnostic apparatus, at least one of the transmission direction and the shape of the transmission beam is changed based on the comparison result of the signal intensities of the same depth in the respective reception directions.

Another ultrasonic diagnostic apparatus according to the present invention simultaneously receives reflected waves from a plurality of different receiving directions in response to one transmission of ultrasonic waves and generates an image based on the received signals. In the diagnostic device, the transmission direction and the reception direction are different between the preceding and following frames.

[0011]

According to the ultrasonic diagnostic apparatus of the present invention, at least one of the transmitting direction and the shape of the transmitting beam is changed based on the comparison result of the signal intensities at the same depth in the respective receiving directions. The sound field in each direction can be made uniform, and the signal strength at the same depth in each reception direction can be made constant, and as a result, uneven sensitivity between reception directions for simultaneous reception can be reduced.

According to another ultrasonic diagnostic apparatus of the present invention, since the transmitting direction and the receiving direction are different between the front and rear frames, the arrangement in the transmitting and receiving direction is changed between the front and rear frames, which causes the front and rear frames to be different. Since the reception intensity in the same receiving direction changes, it is possible to reduce sensitivity unevenness between the receiving directions that receive simultaneously.

[0013]

Embodiments of the ultrasonic diagnostic apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the first embodiment. The sector type electronic scanning type probe 1 is composed of a plurality of transducers 1-1 to 1-M arranged in one dimension. The probe 1 is not limited to the sector type electronic scanning type, and may be, for example, a linear electronic scanning type. Pulse generator 2
The output of A is the transmission delay elements 2B-1 to 2B-M and the pulsar 2C.
-1 to 2C-M are sequentially supplied to the vibrators 1-1 to 1-M. Each transmission delay element 2B-1 to 2B-M and each pulser 2C
-1 to 2C-M are provided corresponding to the transducers 1-1 to 1-M, respectively. A pulser voltage control circuit 2D is connected to the pulsers 2C-1 to 2C-M. By changing the pulse voltage applied to each transducer 1-1 to 1-M by the control of the pulsar voltage control circuit 2D, the aperture width or the transmission voltage weighting of each transducer is changed to change the shape of the transmission beam. be able to. A transmission delay control circuit 2E is connected to the transmission delay elements 2B-1 to 2B-M. By changing the delay amount of each transmission delay element 2B-1 to 2B-M under the control of the transmission delay control circuit 2E, the timing of the pulse voltage applied from the pulsers 2C-1 to 2C-M to each drive vibrator is changed, Thereby, the ultrasonic beam can be transmitted in an arbitrary direction.

The output signals of the transducers 1-1 to 1-M of the probe 1 are preamplifiers 3A-1 to 3A-M provided corresponding to the transducers 1-1 to 1-M, respectively. Is supplied to the reception delay circuits 3B-1 to 3B-N provided in N systems, and different reception directivities are given to the respective systems. The reception delay circuit 3B-1 includes a plurality of reception delay elements 3b-1 to 3b-M respectively connected to the preamplifiers 3A-1 to 3A-M. Similarly to the reception delay circuit 3B-1, the other reception delay circuits 3B-2 to 3B-N also include a plurality of reception delay elements connected to the respective preamplifiers 3A-1 to 3A-M. Reception delay circuit 3B-1
Is connected to the adder 3C-1 and the output signals of the reception delay elements 3b-1 to 3b-M are added to the output of the reception signal of the reflected wave from the direction planned for the system. Is formed. Adders 3C-2 to 3C-N are also connected to the other reception delay circuits 3B-2 to 3B-N, respectively, and receive signals of reflected waves from different receiving directions between the respective systems are formed.

B-mode processing systems 4-1 to 4-N and color flow mapping (CFM) processing systems 5-1 to 5-N are also provided for N systems, and the luminance information and blood flow information of rasters in different directions are parallel. Measured in processing. FIG. 2 shows the B-mode processing system 4
2 is a block diagram showing the configuration of -1. FIG. The other B-mode processing systems 4-2 to 4-N have the same configuration. The output of the adder 3C-1 is a logarithmic amplifier 4A, an envelope detection circuit 4B, an analog /
The signals are sequentially supplied to the digital converter (A / D-C) 4C, which detects the intensities of a large number of sampling points of the raster. This intensity is supplied to the digital scan converter (DSC) 6 as luminance information of the raster, that is, B mode image (tomographic image) information.

FIG. 3 shows a color flow mapping processing system 5-1.
3 is a block diagram showing the configuration of FIG. The other color flow mapping processing systems 5-2 to 5-N have the same configuration. The color flow mapping processing system 5-1 has two channel phase detection circuits 5A-1 and 5A for distinguishing the blood flow direction approaching the probe 1 and the blood flow direction moving away from the probe 1.
-2, low-pass filter (L / P / F) 5D-1, 5D-2,
Analog / digital converter 5E-1, 5E-2, MT
I filters 5F-1 and 5F-2 are provided. Adder 3C-1
The output of is multiplied by the output of the oscillator 5B in the phase detection circuit 5A-1, and the 90 ° phase shifter 5 in the phase detection circuit 5A-2.
It is multiplied with the output of C. As a result, the outputs of the phase detection circuits 5A-1 and 5A-2 include a Doppler shift frequency component and a high frequency component (twice the transmission frequency + Doppler shift frequency). Each high frequency component is removed by the low pass filters 5D-1 and 5D-2. The outputs from the 2-channel low-pass filters 5D-1 and 5D-2 are the cosine and sine components of the Doppler shift frequency, respectively. Each output from the low pass filters 5D-1 and 5D-2 is analog /
It is supplied to the MTI (Moving Target Indicator) filters 5F-1 and 5F-2 for color Doppler through the digital converters 5E-1 and 5E-2, from which fixed reflectors (blood vessel wall, heart wall, etc.) are supplied. Unnecessary reflection components (clutter components) are removed. MTI filters 5F-1, 5F-2
Is supplied to the arithmetic circuit 5G. Although not shown, the arithmetic circuit 5G includes an autocorrelation circuit, an average speed arithmetic circuit, a velocity dispersion arithmetic circuit, and a power arithmetic circuit, and each arithmetic circuit calculates an average velocity V, variance S, and power P. The average speed V, the variance S, and the power P are supplied to the digital scan converter 6. Further, the power P is supplied to the control circuit 8. In this embodiment, the control circuit 8 receives the power P of each raster simultaneously received in different reception directions from the color flow mapping processing systems 5-1 to 5-N, and uses it as a comparison result between powers of the same depth of each raster. Based on this, the transmission delay control circuit 2E is used to control the delay amount of each transmission delay element 2B-1 to 2B-M to change the transmission direction, and the oscillator to be driven is selected via the pulser voltage control circuit 2D. By changing the aperture width by using this method, the sensitivity unevenness between the rasters that are simultaneously received can be uniformly corrected. The details of this modification will be described later.

Next, the operation of this embodiment will be described.
In this embodiment, while repeatedly performing scanning for one frame, the sensitivity unevenness between rasters in the next parallel simultaneous reception is determined based on the sensitivity unevenness between rasters in the parallel simultaneous reception in the current frame scanning. And the opening width. Note that the number of rasters that are simultaneously received is four here. In this case, the reception delay circuit described above,
Four systems are provided for each of the adder, the B-mode processing system, and the color flow mapping processing system. In addition, for the transmission in one direction of the frame this time, a plurality of transducers 1-a to 1-b are selectively driven from all the transducers 1-1 to 1-M. To do. The opening width at this time matches the array width of the selected plurality of transducers 1-a to 1-b.

FIG. 4 shows one transmission direction of the current frame (broken line) and the next transmission direction (dashed line). Numbers 1 to 4 are four reception delay circuits 3
4 shows each of four rasters with different reception directivities of B-1 and 3B-4. In this frame scan, the pulse from the pulse generator 2A is transmitted by the transmission delay elements 2B-1 to 2B.
-Sent to M. The transmission delay elements 2B-1 to 2B-M individually give the delay amount to each pulse based on the delay amount from the transmission delay control circuit 2E for transmitting in the predetermined direction. The pulse provided with this delay amount is supplied to the pulsers 2B-1 to 2B-M. By the control from the pulsar voltage control circuit 2D, drive signals are output only from the pulsars 2B-a to 2B-b, and only the predetermined plurality of transducers 1-a to 1-b are selectively driven. As a result, the transmission beam is transmitted to the subject. Then, the reflected waves from the subject are received by the transducers 1-1 to 1-M. Each received signal is a preamplifier 3A-1-3
It is supplied to the four systems of reception delay circuits 3B-1 to 3B-4 via A-M, where different reception directivities are given to each system, and the adders 3C-1 to 3C-4 provide each system. Is added. The outputs of the adders 3C-1 to 3C-4 are sent to the corresponding B-mode processing systems 4-1 to 4-4, where the intensities of a large number of sampling points are detected for each raster. This intensity is supplied to the digital scan converter 6 as brightness information of each raster, that is, B mode image (tomographic image) information.
The outputs of the adders 3C-1 to 3C-4 are also sent to the corresponding color flow mapping processing systems 5-1 to 5-4, where the blood flow information of a large number of sampling points for each raster, that is, The average speed V, the variance S, and the power P are measured. This power P is supplied to the digital scan converter 6 together with the dispersion S and the average speed V, and is also supplied to the control circuit 8.

As shown in FIG. 4, the control circuit 8 controls the sampling points Q1 to Q4 of each raster at a set constant depth.
The power P is extracted, and the transmission direction and the aperture width are controlled based on these powers to reduce sensitivity unevenness between rasters due to parallel simultaneous reception in the same direction of the next frame. The depth for extracting the power P is usually set to be the same as the focus of the transmission beam, but it may be an arbitrary depth input by an operator from an input device (not shown). Each Q1 ~
Let the power P of Q4 be P1 to P4, respectively. The control circuit 8 controls P1 and P which are equidistant from the scheduled transmission beam.
4. Compare P2 and P3. Where P1> P4, P2
When> P3, the actual transmission beam is No. 1 in the planned direction (dashed line) as shown by the broken line in FIG.
It is judged that it is tilted to the raster side of N0.2. When the comparison result is opposite, of course, the transmission beam is No. 3 and N0.4.
Judging that it is leaning toward the raster side. The control circuit 8
This tilted transmit beam is not visible in the next scan.
The transmission delay control circuit 2E is controlled to change the delay amounts of the transducers 1-a to 1-b driven in this transmission so as to pass through the centers of the rasters of 2 and N0.3. For example, when tilted to the raster side of No. 1 and N0.2 with respect to the planned direction, each delay amount of each transducer 1-a to 1-b is changed from the broken line in FIG. Will be corrected to. When the transducers 1-a to 1-b are driven in the next scan according to the changed delay amount, the transmission beam is changed as shown by the alternate long and short dash line in FIG.
It is modified to pass through the center of rasters No. 2 and N0.3. Therefore, sensitivity unevenness between rasters in parallel simultaneous reception due to the tilt of the transmission beam is reduced.

Further, the control circuit 8 narrows the aperture width of the next scanning based on the comparison result of P1 and P4, P2 and P3 which are equidistant from the scheduled transmission beam, and changes the shape of the transmission beam this time. By changing the divergence to be more divergent than that of the parallel simultaneous reception, the parallel simultaneous reception due to the fact that the transmitted beams are over-focused with respect to the divergence angle of both end rasters, resulting in a significant difference in sound field strength between the rasters Reduces sensitivity unevenness between receiving rasters. Therefore, the control circuit 8
Controls the pulsar voltage control circuit 2D, and as shown in FIG. 6, in the next scanning, the pulsar 2C-a 'which is smaller than this time is used.
The drive signal is limited to be output only from ~ 2C-b '. At this time, the number of pulsers that output the drive signal next time will be smaller than this time, so by increasing the pulse voltage from each pulser 2C-a'-2C-b 'within the range of the safety standard, It is desirable to prevent a decrease in energy and thereby prevent S / N degradation due to a decrease in received signal strength. By narrowing the aperture width in this way, the next transmission beam is spread, as shown in FIG.
The contour line extends from T to T '. As a result, in the next scanning, the sound field intensities between the rasters come close to each other, which reduces the sensitivity unevenness between the rasters in parallel simultaneous reception.

As described above, in this embodiment, the transmission direction of the next scan is corrected and the aperture width of the transmission beam is changed based on the comparison of the power P at the same depth of each raster in the current scan. It is possible to reduce the sensitivity unevenness between the rasters by making the sound field intensity between the rasters of parallel simultaneous reception in the next scan constant.

In this embodiment, when the comparison result of the powers P1 and P4 or P2 and P3 equidistant from the transmission beam is within a certain range, the transmission direction and aperture width of the next scan are not changed. You may do it. Further, in order to spread the transmission beam, the number of drive vibrators is reduced to narrow the aperture width, but the transmission beam may be diffused by the transmission delay control regardless of the aperture width.
Further, although the pulse voltage to each driven vibrator is made constant and the aperture width is changed, in addition to this, for example, the voltage applied to each vibrator may be changed to change the transmission beam width.

Next, a second embodiment will be described. The sensitivity unevenness between the rasters in parallel simultaneous reception is mainly due to the difference in sensitivity between the center side raster and the end side raster among a plurality of rasters that are simultaneously received. This embodiment is characterized in that the transmission direction and the reception direction are changed for each frame, and rasters having the same number are averaged between frames to reduce sensitivity unevenness between the rasters. .

FIG. 8 is a block diagram showing the configuration of this embodiment. In this figure, the same parts as those in FIG. 1 are designated by the same reference numerals as those in FIG. 1 and their detailed description is omitted. The transmission delay control circuit 2G of the present embodiment makes the respective delay amounts of the transmission delay elements 2B-1 to 2B-M different at least between two frames before and after, or between even-numbered frames and odd-numbered frames,
The transmission directivity of the transmission beam of the same number is changed between the preceding and succeeding frames. The reception delay control circuit 9 also changes the reception directivity of each of the N reception delay circuits 3B-1 to 3B-N between at least two frames before and after, or between even-numbered frames and odd-numbered frames. Interframe averaging circuit 10
Executes the averaging process of the raster data of the same raster number between at least two frames from the B mode processing system 4-1 to 4-N or the color flow mapping processing system 5-1 to 5-N. The result is digital scan converter 6
Output to.

FIG. 9 shows the configuration of the inter-frame averaging circuit 10.
Shown in. In the inter-frame averaging circuit 10, L-2 frame memories 10B,
10D and 10F are provided, and each frame memory 10B,
Information on three consecutive images is stored in 10D and 10F. The image information of the B-mode processing system 4-1 to 4-N or the color flow mapping processing system 5-1 to 5-N is the multiplier 10A.
Is supplied to the adder 10H via. Frame memory 1
0B, the image information of the previous frame of the image information stored in 0B, the image information of the previous frame of the image information stored in the frame memory 10D, the image information of the previous image information stored in the frame memory 10F. The image information of each frame is B mode processing system 4-1 to 4 respectively.
-N or the color flow mapping processing systems 5-1 to 5-N, the data is read in synchronization with the image information supplied, and supplied to the adder 10H via the multipliers 10C, 10E, and 10G, respectively. The weighting factors cof1, cof2, cof3 and cof4 of the multipliers 10A, 10C, 10E and 10G are set depending on the pattern selected from the input device (not shown). According to the first pattern, the weighting factors cof1, cof2,
cof3 and cof4 are set to 0.5, 0.5, 0, 0, respectively. By the second pattern, the weighting factors cof1, co
f2, cof3 and cof4 are all uniformly set to 0.25. That is, in the first pattern, the simple averaging process is performed between two frames before and after, and in the second pattern, the simple averaging process is performed between four consecutive frames. The average result output from the adder 10H is supplied to the digital scan converter 6.

Next, the operation of this embodiment configured as described above will be described. First, the operation when the first pattern is selected will be described. When the first pattern is selected, as described above, the multipliers 10A, 10C, 10E,
The weighting factors cof1, cof2, cof3 and cof4 of 10G are set to 0.5, 0.5, 0 and 0, respectively. Then, scanning is executed in the following procedure.

FIG. 10 is a diagram showing a scanning procedure according to the first pattern. It is assumed that the number of rasters simultaneously received by parallel simultaneous reception is four. In frame 1, the transmission beam is scanned between raster numbers 2 and 3, raster numbers 6 and 7, raster numbers 10 and 11, and so on. The raster numbers 1 to 4 and 5 are also set for the four rasters that are simultaneously received in parallel corresponding to the respective transmission directions.
It switches to 8, 9, 12 ... The received signal of frame 1 obtained by such scanning is the B-mode processing system 4
-1 to 4-4 or color flow mapping processing system 5-1 to 5
-4, it is supplied to the inter-frame averaging circuit 10 as image information and stored in the frame memory 10B.

Next, scanning of frame 2 is executed. In this frame 2, the transmission beam has half the number of rasters (here, 2) that are simultaneously received from the previous frame 1.
It will be sent after a delay of (book). That is, here the transmit beam is in the middle of raster numbers 4 and 5, raster numbers 8 and 9.
Is scanned in the middle of. Accordingly, the four rasters that are simultaneously received in parallel are also shifted from the previous frame 1 by half the number of rasters that are simultaneously received (two in this case). That is, the combination of four rasters that are simultaneously received by parallel simultaneous reception corresponds to each transmission beam, and the raster number is shifted by two from the previous frame 1 by 2 and the raster numbers 3 to 4 are the last raster. The raster L is scanned. The received signal of frame 2 obtained by such scanning is the B mode processing systems 4-1 to 4-4.
Alternatively, it is supplied to the adder 10H via the multiplier 10A of the inter-frame averaging circuit 10 via the color flow mapping processing systems 5-1 to 5-4, and is also supplied to the frame memory 10B and sequentially stored. At this time, the received signal of the frame 1 stored in the frame memory 10B is sequentially supplied to the adder 10H via the multiplier 10C in synchronization with the input of the received signal of the frame 2. As a result, the adder 1
The data of the frame 1 and the data of the frame 2 are input to the position 0H after being aligned, and the two frames are added, and the result is supplied to the digital scan converter 6. In this way, the simple averaging process is performed between the two frames before and after, so that unevenness in sensitivity between the raster on the center side and the raster on the end side is mainly reduced.

In the next frame 3, scanning is performed in the same manner as in frame 1, and the image information thereof is supplied to the adder 10H via the multiplier 10A, where it is supplied from the frame memory 10B via the multiplier 10C. It is subjected to the averaging process with the frame 2 and supplied to the digital scan converter 6. After that, the same scanning is repeated for the odd-numbered frame as the frame 1 and for the even-numbered frame as the frame 2, and the averaging process is sequentially performed between the two frames before and after the same, and the result is supplied to the digital scan converter 6.

As described above, in the first pattern, the combination of rasters that perform parallel simultaneous reception corresponding to the transmission beam direction and each transmission beam in odd and even frames is changed so that each raster is simultaneously processed in the preceding and subsequent frames. By alternately arranging the positions on the center side and the end side of the reception and performing the averaging process between the rasters of the same number between the two frames before and after, the raster on the center side and the raster on the end side of the simultaneous reception occur. The unevenness in sensitivity is reduced, and as a result, the image quality is improved.

Next, the operation when the second pattern is selected will be described. When the second pattern is selected,
As described above, the multipliers 10A, 10C, 10E, 10G
The weighting factors cof1, cof2, cof3, and cof4 are uniformly set to 0.25. Then, scanning is executed in the following procedure.

FIG. 11 is a diagram showing a scanning procedure according to the second pattern. Also in this case, the number of rasters simultaneously received by parallel simultaneous reception will be described as four. In frame 1, the transmission beam is scanned between the raster numbers 2 and 3, the raster numbers 6 and 7, and so on.
The four rasters are sequentially switched. The received signal of frame 1 obtained by such scanning is the B-mode processing systems 4-1 to 4-4 or the color flow mapping processing system 5-1.
Through 5-4, the inter-frame averaging circuit 10 as image information
Are stored in the frame memory 10B.

Next, scanning of frame 2 is executed. In this frame 2, the transmission beam is transmitted in a direction shifted by one raster from the case of the previous frame 1. That is, here, the transmission beam is scanned between raster numbers 3 and 4, raster numbers 7 and 8, and so on. In response to this, the combination of four rasters for which parallel simultaneous reception is performed is shifted by one raster from the case of the previous frame 1. That is, four rasters are sequentially scanned from raster number 2 which is one raster number shifted from the previous frame 1 corresponding to each transmission beam. The received signal of the frame 2 obtained by such scanning is passed through the B mode processing system 4-1 to 4-4 or the color mapping flow processing system 5-1 to 5-4, and the frame memory of the interframe averaging circuit 10 is used. Stored in 10B. At this time, the previous frame 1 stored in the frame memory 10B
The image information of is transferred to and stored in the frame memory 10D.

Next, scanning of frame 3 is executed. In this frame 3, the transmission beam is transmitted in a direction shifted by one raster from the case of the previous frame 2. That is, here, the transmission beam is scanned between the raster numbers 4 and 5 and the raster numbers 8 and 9. In response to this, the combination of four rasters for which parallel simultaneous reception is performed is shifted by one raster from the case of the previous frame 2. That is, raster lines corresponding to each transmission beam are sequentially scanned one by one from the preceding frame 1 by raster numbers 3 to 4, respectively. The received signal of the frame 3 obtained by such scanning is sent to the frame memory of the inter-frame averaging circuit 10 through the B mode processing system 4-1 to 4-4 or the color mapping flow processing system 5-1 to 5-4. Stored in 10B. The previous frame 2 stored in the frame memory 10B at this time
The image information of is transferred to and stored in the frame memory 10D. In addition, the image information of the frame 1 before the second time stored in the frame memory 10D is stored in the frame memory 10D.
It is transferred to F and stored.

In this way, all frame memories 10B, 10
After the image information of three consecutive frames D and 10F is stored, the averaging process is executed from the next frame. Scanning of frame 4 is performed. In this frame 4, the transmission beam is transmitted in a direction shifted by one raster from the case of the previous frame 3. That is, here, the transmission beam is scanned between the raster numbers 5 and 6, the raster numbers 9 and 10, and so on. In response to this, the combination of four rasters for which parallel simultaneous reception is performed is shifted by one raster with respect to the case of the previous frame 3. That is, for each transmission beam, the previous frame 1
The raster numbers are sequentially scanned one by one from the raster number 4 whose raster number is shifted by one. The received signal of the frame 4 obtained by such scanning is the B mode processing system 4
-1 to 4-4 or color mapping flow processing system 5-1 to 5
Is supplied to the adder 10H via the multiplier 10A of the inter-frame averaging circuit 10 via −4. At this time, the image information of consecutive frames 1, 2 and 3 stored in the frame memories 10B, 10D and 10F is also multiplied by the multiplier 10 respectively.
It is supplied to the adder 10H via C, 10E, and 10G. The adder 10H subjects the image information of four consecutive frames to addition processing, and supplies the result to the digital scan converter 6. Each frame memory 10
The stored contents of B, 10D, and 10F are consecutive 3
It is sequentially updated to one frame 4, 3, 2. From the next frame 5, the scanning procedure of the frames 1 to 4 is repeated, and the consecutively acquired three frames of the presently acquired frame are sequentially subjected to the averaging process, and the result is sequentially supplied to the digital scan converter 6. To be done.

As described above, in the second pattern, the direction of transmission beams and the combination of rasters for parallel simultaneous reception are changed by one raster for each frame, and the parallel simultaneous transmission is performed while changing the arrangement of each raster with respect to the transmission beams. By performing the averaging process for four frames corresponding to the number of rasters to be received, it is possible to reduce sensitivity unevenness between rasters due to the difference in position with respect to the transmission beam, and thus to improve image quality.

Next, a third embodiment will be described. The configuration of the present embodiment is nothing but the configuration in which the inter-frame averaging circuit is removed from the configuration of FIG. In the second embodiment described above, the transmission beam and the reception directivity are shifted for each frame while scanning, and the averaging process is performed among a plurality of frames to reduce the sensitivity unevenness. The procedure is the second above
This is exactly the same as the case of the embodiment, and the image information of each frame is immediately displayed without being subjected to the averaging process.

As described above, the moving image is displayed by sequentially switching the image information of the frames obtained by scanning the transmission beam and the reception directivity for each frame, thereby causing uneven sensitivity between rasters of each frame. However, the position where the sensitivity unevenness occurs differs for each frame, and as a result, an effect equivalent to the averaging process similar to that of the second embodiment occurs due to the human afterimage effect, and the sensitivity unevenness cannot be recognized. . The present invention is not limited to the above-described embodiments, but can be modified in various ways without departing from the scope of the present invention.

[0039]

As described above, according to the ultrasonic diagnostic apparatus of the present invention, at least one of the transmitting direction and the shape of the transmitting beam is changed based on the comparison result of the signal intensities at the same depth in each receiving direction. As a result, the sound field in each reception direction for simultaneous reception is made uniform, the signal strength at the same depth in each reception direction is made constant, and sensitivity unevenness between reception directions for simultaneous reception is reduced.

Further, according to another ultrasonic diagnostic apparatus of the present invention, since the transmission direction and the reception direction are different between the front and rear frames, the arrangement of each reception direction with respect to the transmission direction changes between the front and rear frames. By this, the reception intensity of the same reception direction of the preceding and following frames changes, so that it is possible to reduce sensitivity unevenness between the reception directions of simultaneous reception.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of an ultrasonic diagnostic apparatus according to the present invention.

FIG. 2 is a block diagram showing a configuration of a B-mode processing system shown in FIG.

3 is a block diagram showing a configuration of a color flow mapping processing system in FIG.

FIG. 4 is a diagram showing a certain transmission direction and rasters for parallel simultaneous reception corresponding thereto according to the first embodiment.

FIG. 5 is a diagram showing a change in delay amount between preceding and following frames according to the first embodiment.

FIG. 6 is a view showing a change in opening width between front and rear frames according to the first embodiment.

FIG. 7 is a diagram showing the counting of transmitted beams that changes according to changes in the aperture width.

FIG. 8 is a block diagram showing the configuration of a second embodiment of the ultrasonic diagnostic apparatus according to the present invention.

9 is a block diagram showing a configuration of an inter-frame averaging circuit of FIG.

FIG. 10 is a diagram showing a scanning procedure according to the first pattern of the second embodiment.

FIG. 11 is a diagram showing a scanning procedure according to a second pattern of the second embodiment.

[Explanation of symbols]

1 ... Probe, 2A ... Pulse generator, 2B-1 to 2B-M ...
Transmission delay element, 2C-1 to 2C-M ... Pulser, 2D ... Pulser voltage control circuit, 2E ... Transmission delay control circuit, 3A-1 to 3A
-M ... Preamplifier, 3B-1 to 3B-N ... Reception delay circuit, 3C
-1 to 3C-N ... Adder, 4-1 to 4-N ... B mode processing system, 5
-1 to 5-N ... Color flow mapping processing system, 6 ... Digital scan converter, 7 ... Monitor, 8 ... Control circuit.

Claims (2)

[Claims] 1. An ultrasonic diagnostic apparatus for simultaneously receiving reflected waves from a plurality of different receiving directions in response to one transmission of ultrasonic waves and generating an image based on the received signals. An ultrasonic diagnostic apparatus characterized in that at least one of a transmission direction and a shape of a transmission beam is changed based on a comparison result of signal intensities at the same depth. 2. An ultrasonic diagnostic apparatus for simultaneously receiving reflected waves from a plurality of different receiving directions in response to one transmission of ultrasonic waves and generating an image based on the received signals. An ultrasonic diagnostic apparatus characterized in that directions are different between front and rear frames.