JP6709142B2 - Ultrasonic imaging apparatus, signal processing apparatus, and signal processing method for ultrasonic imaging apparatus - Google Patents

Description

The present invention relates to an ultrasonic imaging apparatus and a received signal processing method.

To improve the frame (volume) rate of a three-dimensional image, an ultrasonic imaging method for sampling received data at high speed by setting a received scan line in an imaging area coarser than a normal received scan line is patented. Proposed in Reference 1 and the like.

In the technique of Patent Document 1, the reception data of the pixels between the coarsely set reception scan lines is obtained by interpolating the interpolation data obtained by the interpolation process or by obtaining the reception data of the corresponding pixel in the past scan period. Is inserted to obtain three-dimensional volume data. Specifically, the comparator compares the interpolated data value with the past received data for each pixel, and if the two are significantly different, it indicates that the subject is moving, so the interpolated data value is received. If they are inserted between the scan lines and both are substantially equal, it means that the subject does not move. Therefore, the past received data value is inserted to create the three-dimensional volume data set. Thereby, the technique of Patent Document 1 generates the same three-dimensional volume data as that at the time of full sampling along the high-density receiving scan line for the region to be imaged, and achieves both high volume rate and high image quality.

Special table 2013-526389 gazette

In the technique of Patent Document 1, when it is determined by the comparator whether the interpolation data and the past reception data are equal, it is necessary to compare the difference between the values of the interpolation data and the past reception data with some threshold value. If not set properly, the image quality cannot be improved. For example, if the threshold value is too large, it is determined that the interpolation data value and the received data value in the past are substantially equal, and the received data value in the past is selected. Becomes Conversely, if the threshold value is too small, if the interpolated data value and the past received data value are slightly different, it is determined that they are different, and the interpolated data value is selected. Absent.

Further, since various tissues are mixed in the imaging target, various types of luminance distribution coexist in one image, and the appropriate threshold value for improving image quality differs depending on the type of luminance distribution. However, in the technique of Patent Document 1, since all the pixels are determined by one comparator, the threshold cannot be changed according to the type of brightness distribution.

An object of the present invention is to generate an ultrasonic image with high quality and suppressed false images at high speed using interpolation data and past reception data.

The present invention mixes the interpolated data obtained for a certain point in the imaging target with the past received data for that point to generate the received data for that point by calculation. At this time, the mixing ratio of the interpolated data and the past received data is determined based on the value of the interpolated data and the value of the past received data at that point. That is, the ultrasonic imaging apparatus of the present invention transmits an ultrasonic wave to an imaging target, receives an ultrasonic wave returned from the imaging target at each transmission, and converts the ultrasonic wave into a reception signal, and an imaging region of the imaging target. The number of receive scan lines required for imaging is set, a predetermined number of receive scan lines is selected, and receive data for each of a plurality of points on the selected receive scan line is generated from the receive signal. Section, a memory for storing the reception data generated by the reception section, and a plurality of reception scan lines not selected by the reception section on one or more reception scan lines by interpolating the reception data generated by the reception section. The interpolation data generation unit that generates the interpolation data corresponding to the reception data of the point by the operation, and the past reception data generated from the reception signal by the reception unit at the same point as the point where the interpolation data is obtained are stored in the memory. And a mixing unit that mixes the interpolated data with the past received data. The mixing unit determines a mixing ratio of the interpolation data and the past reception data based on the interpolation data value and the past reception data value.

The ultrasonic imaging apparatus of the present invention can generate an ultrasonic image with high image quality and suppressed false images at high speed by using the interpolation data and past reception data.

1 is a block diagram showing a configuration of an ultrasonic imaging apparatus according to a first embodiment of the present invention. (A)-(e) Explanatory drawing which shows the example of the receiving scanning line of Embodiment 1. Block diagram showing the configuration of the ultrasonic imaging apparatus of the second embodiment FIG. 3 is a block diagram showing a detailed configuration of a mixing coefficient calculation unit according to the second embodiment. The flowchart which shows operation|movement of the control part of Embodiment 2. FIG. 6 is a diagram showing an example of a screen for a user interface of the second embodiment. (A) is the position of the transmission scan line set in one scan, (b) is the position of the reception scan line that generates interpolation data, (c) is the reception where the mixed data after the mixing process is stored. Explanatory drawing showing the position of each scanning line FIG. 3 is a block diagram showing a detailed configuration of a mixing coefficient calculation unit according to the third embodiment. A graph showing a distribution of received data values calculated by the distribution calculation unit of the third embodiment Block diagram showing the configuration of the ultrasonic imaging apparatus of the fifth embodiment

An ultrasonic imaging apparatus according to an embodiment of the present invention will be described.

The ultrasonic imaging apparatus (ultrasound transmission/reception apparatus) of the present embodiment mixes the interpolation data obtained for a certain point in the imaging region and the past reception data for that point to obtain the reception data for that point. Is generated by calculation. At this time, the mixing ratio of the interpolated data and the past received data is determined based on the value of the interpolated data at that point and the value of the past received data.

As described above, since the mixed data obtained by mixing the interpolated data and the past received data is used as the pixel data, the occurrence of the false image is suppressed as compared with the case where the interpolated data and the past received data are selectively used. In addition, the image quality can be improved. Further, since the mixing ratio is determined based on the value of the interpolation data and the value of the past reception data for the point of the pixel, it is possible to set an appropriate mixing ratio for each point in the imaging region, It is possible to provide a smooth three-dimensional image with no unevenness over the entire imaging region.

<<Embodiment 1>>
The ultrasonic imaging apparatus according to the first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a block diagram showing the configuration of the ultrasonic imaging apparatus 100 according to the first embodiment. 2A to 2E are explanatory views showing an example of the reception scanning line 21.

The ultrasonic imaging apparatus 100 of FIG. 1 includes a receiving unit 104, a memory 20, an interpolation data generating unit 10, and a mixing unit 3. In the configuration of FIG. 1, the ultrasonic imaging apparatus 100 further includes an image processing unit 107. The ultrasonic imaging apparatus 100 is also connected to a display device 122 that displays various screens and an ultrasonic probe 108 that transmits and receives ultrasonic waves.

The ultrasonic probe 108 transmits ultrasonic waves to the imaging target 120 under the control of a transmission unit (not shown) of the ultrasonic imaging apparatus, receives ultrasonic waves returned from the imaging target 120 at each transmission, and converts them into reception signals. To do. For example, the ultrasound probe 108 has a plurality of arrayed transducers, transmits ultrasounds 121 toward the imaging target 120 from each transducer along a predetermined transmission scan line, and then performs imaging. Each transducer receives the ultrasonic echo 122 returning from the target 120, and each transducer converts the ultrasonic echo 122 into a reception signal which is an electric signal. Further, the ultrasonic probe 108 outputs the received signal to the receiving unit 104.

As shown in FIG. 2A, the reception unit 104 sets as many reception scan lines 21 as necessary for imaging in the imaging region 120a of the imaging target 120, and receives a predetermined number of reception scan lines 21. The scanning line 21a (FIG. 2B) is selected. Reception data for each of the plurality of selected points on the reception scanning line 21a is generated from the reception signal of the ultrasonic probe 108. For example, the reception signals output from the respective transducers of the ultrasonic probe 108 are delayed (aligned) so that the reception signals output from the respective transducers are focused on a preset point on the reception scanning line 21a. Phased and then added to obtain a phasing addition signal, and the phasing addition signal is used as reception data.

The ultrasonic probe 108 sequentially transmits the ultrasonic waves 121 along a plurality of roughly set transmission scan lines, obtains a reception signal for each transmission, and the receiving unit 104 sets the same position as the transmission scan lines. It is also possible to adopt a transmission/reception method of generating reception data for one reception scanning line 21a set to. Further, the ultrasonic wave 108 is transmitted from the ultrasonic probe 108, and the reception unit 104 sets a plurality of reception scanning lines 21a for the reception signal obtained in one transmission, and the reception scanning lines 21a on each reception scanning line 21a are set. Received point data may be generated.

The reception data generated by the reception unit 104 for the selected point on the reception scanning line 21a is stored in the memory 20. The memory 20 has an area 22 for storing the current received data and an area 23 for storing the past received data. The area 22 for storing the reception data of this time includes an area (selection reception scanning line area) 22a for storing reception data of a point on the selected reception scanning line 21a and a point on the reception scanning line 21b which is not selected. It is divided into an area (non-selected reception scanning line area) 22b for storing mixed data (or interpolation data). The reception data generated by the reception unit 104 for the point on the reception scanning line 21a is stored in the area 22a.

The interpolation data generation unit 10 interpolates the reception data of a plurality of points on the reception scanning line 21a generated by the reception unit 104, so as to interpolate a plurality of reception scanning lines 21b (FIG. 2C) not selected. Interpolation data corresponding to the received data for the point is generated by calculation. A known calculation method is used as the interpolation processing method. For example, the average value of the reception data of the points on the plurality of reception scanning lines 21a located so as to sandwich the points on the reception scanning line 21b may be used as the interpolation value.

The mixing unit 3 includes a mixing coefficient calculation unit 30 and a mixing processing unit 40. The mixing coefficient calculation unit 30 stores the reception data generated by the reception unit 104 in the past in the memory 20 with respect to the point whose position is the same as or corresponds to the point on the reception scanning line 21b where the interpolation data generation unit 10 generated the interpolation data. Read from the area 23. Then, the mixing ratio (mixing coefficient) of the interpolation data and the past reception data is determined based on the read value of the past reception data and the value of the interpolation data. For example, the mixing coefficient calculation unit 30 determines the mixing coefficient according to the ratio or difference between the value of the past reception data and the value of the interpolation data generated this time. The mixing processing unit 40 mixes past reception data and interpolation data according to the mixing coefficient. The mixed data is stored in the area 22b in the memory 20 as the reception data for the point for which the interpolation data generation unit 10 obtained the interpolation data.

As a result, in the storage area 22 of the present reception data in the memory 20, for the reception data of each point on the reception scanning line 21a selected by the receiving unit 104 and each point on the reception scanning line 21b not selected. The mixed data obtained by the mixing process is stored.

Therefore, the image processing unit 107 generates an image by using the received data and the mixed data in the storage area 22 of the memory 20, so that the receiving unit 104 does not generate the received data with respect to the point on the reception scan line 21b. Also generates an image and displays it on the connected display device 122. Therefore, the ultrasonic imaging apparatus 100 of this embodiment can display an image at a high frame rate (volume rate).

At this time, in the present embodiment, the reception data on the non-selected reception scanning line 21b is mixed with the interpolation data and the past reception data by the mixing coefficient determined based on the interpolation data value and the past reception data value. Therefore, as compared with the case where the interpolation data and the past reception data are selectively used, it is possible to improve the image quality while suppressing the generation of false images. Further, since the mixing coefficient is determined based on the interpolation data value at that point and the past reception data value, it is possible to set an appropriate mixing coefficient for each point within the imaging area 120a. Therefore, the false image can be suppressed and the image quality can be improved according to the luminance distribution of the image of the imaging target 120. In other words, the mixing coefficient is calculated according to the past received data and the interpolation data, so that it is always variable depending on the timing of imaging and the region, and it is possible to set an appropriate mixing coefficient both temporally and spatially. it can. Therefore, it is possible to provide a smooth image without unevenness in the entire imaging region 120a.

Further, at the time of imaging the next frame, after moving the data in the area 22 of the memory 20 to the area 23 as past reception data, the receiving unit 104 selects the previous frame as shown in FIG. 2D. It is only necessary to select the improper reception scanning line 21b and generate reception data at a point on the reception scanning line 21b. The interpolation data generation unit 10 generates the interpolation data on the reception scanning line 21a not selected by the reception unit 104, and uses the generated interpolation data and the previous reception data with the mixing coefficient determined based on these values. Mixed data (received data) is generated (FIG. 2(e)). The image processing unit 107 uses the reception data on all the reception scanning lines 21 to generate an image and displays it on the display device 122. As a result, the reception unit 104 selects all the reception scanning lines 21 in two frames and generates reception data, but an image can be displayed for each frame.

2A to 2E show an example in which all the reception scanning lines 21 are selected in two frames, but the present embodiment is not limited to this configuration, and three or more frames are selected. Alternatively, all the reception scan lines 21 may be selected by.

2A to 2E show the case where the imaging region 120a is two-dimensional for convenience of illustration, but this embodiment is of course applicable to a three-dimensional imaging region (volume). Is.

The functions of the reception unit 104, the interpolation data generation unit 10, and the mixing unit 3 may be realized by hardware, or some or all of them may be realized by software. When it is realized by hardware, the reception unit 104, the interpolation data generation unit 10, and the mixing unit are combined by hardware such as a custom IC such as an ASIC (Application Specific Integrated Circuit) or a programmable IC such as an FPGA (Field-Programmable Gate Array). The unit 3 is configured and the IC circuit is designed so that the functions described above are realized. When implemented by software, a part of or all of the reception unit 104, the interpolation data generation unit 10, and the mixing unit 3 are configured by a processor (for example, a CPU (Central Processing Unit)) and a memory in which a program is stored in advance. To do. These functions are realized by the processor reading and executing the program.

Hereinafter, the ultrasonic imaging apparatus of the present embodiment will be described more specifically with reference to the second and subsequent embodiments.

<<Embodiment 2>>
An ultrasonic imaging apparatus according to the second embodiment will be described with reference to FIGS. 3 and 4. FIG. 3 is a block diagram showing a configuration of the ultrasonic imaging apparatus 110 of the second embodiment, and FIG. 4 is a block diagram showing a detailed configuration of the mixing coefficient calculation unit 30.

In the second embodiment, when the same imaging target 120 is imaged, the reception data actually obtained in the past frame (scan) is more reliable than the interpolation data, and the image quality is better when the past reception data is used. The mixing coefficient of the interpolated data and the past received data is determined based on the idea that is improved. Specifically, the closer the imaging target 120 is to the state of the current frame and the past frame (for example, there is no motion, there is no change in the physical property value causing ultrasonic echo), the more the past frame is received. The mixing coefficient is determined so that the received data is used more. Therefore, in the ultrasonic imaging apparatus 110 according to the second embodiment, the mixing coefficient calculating unit 30 calculates the mixing coefficient based on the index calculating unit 31 that calculates the index of the state closeness, and the coefficient calculating unit based on the index. 32.

Hereinafter, the ultrasonic imaging apparatus 110 according to the second embodiment will be described in more detail. In the following description, the same components as those of the ultrasonic imaging apparatus according to the first embodiment will be designated by the same reference numerals and description thereof will be omitted.

The ultrasonic probe 108 of the ultrasonic imaging apparatus 110 according to the second embodiment has a configuration in which transducers are two-dimensionally arranged and transmits and receives ultrasonic waves in three-dimensional directions. As shown in FIG. 3, in the ultrasonic imaging apparatus 110, in addition to the configuration of FIG. 1 described in the first embodiment, a transmission/reception switching unit 101, a transmission unit 102, a transmission scan position determination unit 103, a control unit 106, a user. An interface (UI) 121 and a signal processing unit 105 are arranged. An interpolation data generation unit 10, a mixing unit 3 (mixing coefficient calculation unit 30, mixing processing unit 40) and a memory 20 are arranged in the signal processing unit 105. The transmission/reception switching unit 101 is connected to the ultrasonic probe 108, and the transmission unit 102 and the reception unit 104 are connected to the transmission/reception switching unit 101.

The UI 121 is an operation input unit that receives settings such as imaging parameters from the operator. The display device 122 may also serve as the UI 121. The control unit 106 controls each unit based on the imaging parameter received by the UI 121 to execute imaging.

The transmission scan position determining unit 103, under the control of the control unit 106, the position of the transmission scanning line 221 (see FIG. 7 to be described later) of the ultrasonic wave 121 for each transmission, and the reception scan in which the reception unit 104 generates reception data. The position of the line 21a is determined, and the transmitting unit 102 and the receiving unit 104 are instructed.

The transmission unit 102 generates a transmission signal (electrical signal) for transmitting the ultrasonic wave 121 from the ultrasonic probe 108 in the direction of the transmission scan line 221 determined by the transmission scan position determination unit 103, and via the transmission/reception switching unit 101. And outputs it to the plurality of transducers of the ultrasonic probe 108.

The reception unit 104 receives a reception signal from the ultrasonic probe 108 via the transmission/reception switching unit 101. Then, the reception unit 104 selects the reception scan line 21a instructed by the transmission scan position determination unit 103, and generates reception data for a point (pixel) on the reception scan line 21a as in the first embodiment. The data is stored in the area 22a of the memory 20.

In the present embodiment, the transmission probe position determining unit 103 sequentially transmits the ultrasound probe 108 to the plurality of transmission scan lines 221 (see FIG. 7) set in the imaging region 120a in one scan (1 (Scanning), a reception signal is obtained for each transmission, and the reception unit 104 generates reception data for a point on one reception scanning line 21a at the same position as the transmission scanning line 221.

Similar to the first embodiment, the interpolation data generation unit 10 generates interpolation data for the points (pixels) on the reception scanning line 21b that the reception unit 104 has not selected, using the reception data generated by the reception unit 104. To do. Unlike the first embodiment, the interpolation data generation unit 10 stores the generated interpolation data in the area of the memory 20 for storing the reception data of the non-selected reception scanning line 21b. As a result, even if the received data of the past frame is not yet stored in the area 23 of the memory 20 and the mixing unit 3 cannot calculate the mixed data because it is immediately after the start of image capturing, this interpolation is performed. The image processing unit 107 is configured to generate and display an image using the data.

As described above, the mixing coefficient calculating unit 30 of the mixing unit 3 calculates the mixing coefficient C1 and C2 based on the index calculating unit 31 that calculates the index R of the closeness of the state (for example, no movement). And a coefficient calculation unit 32 based on an index to be calculated. The index calculation unit 31 calculates the index R by the following formula (1). The index-based coefficient calculation unit 32 calculates the mixing coefficients C1 and C2 at the point where the interpolation data generation unit 10 has calculated the interpolation data value, using the following equation (2).

R=A/B (1)
However, B is the interpolation data value obtained in the current scan, and A is the reception data value generated by the receiving unit 104 in the past scan (frame) at the point where the interpolation data value B was obtained.

C1=R, C2=(1-R) (2)
The mixing processing unit 40 calculates the mixed data value D by the following formula (3).

D=A*C1+B*C2 (3)
The index R is closer to 1 as the interpolated data value B and the past received data value A are closer to each other, indicating that the state of the imaging target 120 at the time of the current scan (frame) and the past scan is closer. From the above equation (2), since the mixing coefficient C1 of the past received data value A is R and the mixing coefficient C2 of the interpolation data value B is (1−R), from the equation (3), the mixed data value D The ratio of the received data value A increases as the state of the imaging target in the current scan and the past scan becomes closer, and the ratio of the interpolation data value B increases as the state becomes different.

The closeness of the state means that, for example, the point for which the interpolation data value was obtained does not move (is not displaced) between the current scan and the previous scan, and changes in physical properties such as reflection and scattering that cause ultrasonic echo. Indicates that there is no. In the second embodiment, the closeness of the state is obtained as the index R, and the closer the state is to the closer the state according to the value of the index R, the more the past reception value actually generated by the receiving unit 104 than the interpolation data value B obtained by the calculation. Mixed data (received data) having a large mixing ratio of the data value A can be generated by calculation. This makes it possible to provide a high-quality three-dimensional image with little spatial unevenness in the images of the reception scanning line 21a selected this time and the reception scanning line 21b not selected.

Next, the operation of each unit of the ultrasonic imaging apparatus 110 according to the second embodiment will be described with reference to FIGS. 5 to 7. FIG. 5 is a flowchart showing the operation of the control unit 106, and FIG. 6 is an example of a screen for the user interface. FIG. 7A shows the position of the transmission scanning line 221 (which is the same as the reception scanning line 21a in the second embodiment) set in one scan, and FIG. 7B shows the position of the reception scanning line 21b that generates interpolation data. As for the position, FIG. 7C shows the position of the reception scanning line 21b in which the mixed data after the mixing process is stored.

The control unit 106 is configured to include a processor such as a CPU and a memory in which a program is stored in advance, and the processor reads and executes the program in the memory to control each unit as in the flow of FIG. To operate. The receiving unit 104, the interpolation data generating unit 10, and the mixing unit 3 may have a configuration in which their functions are realized by hardware as described in the first embodiment, or their functions may be realized by software. It may be configured. Similarly, the transmission scan position determination unit 103 and the transmission unit 102 may have a configuration in which these functions are realized by either hardware or software.

As in the flowchart of FIG. 5, the control unit 106 causes the display device 122 to display the screen 61 of FIG. 6, and accepts the setting of the imaging parameter from the operator via the UI 121 (step 501 ). The screen 61 of FIG. 6 shows N when the volume (frame) rate is set to normal or high, that is, the area 62 for the operator to select the type of volume rate and the high volume rate. And an area 63 for the operator to input the value of N at double speed. As a result, the control unit 106 accepts the type of volume rate and the N value of N times speed in the case of a high-speed volume rate as an imaging parameter from the operator via the UI 121 (step 501). Hereinafter, a case where the type of volume rate is high will be described.

The control unit 106 transfers the N value to the transmission scan position determination unit 103 and instructs it to determine the position of the transmission scan line 221. The transmission scan position determination unit 103 has a built-in memory that stores a pattern that defines in advance the position to set the transmission scan line 221 in each scan for each N value, and is instructed by the control unit 106. The pattern of the transmission scanning line 221 corresponding to the N value is read out and set in the transmission unit 102 (step 503).

FIG. 7A shows the position of the transmission scan line 221 (=reception scan line 21a) in the first to fourth scans when N=4. Here, since the scanning speed is N times (N=4), once the scanning is repeated N times, the transmission is completed once for all the transmission scanning lines 221 required for imaging the three-dimensional imaging region 120a. In the scan 1, the 1/N (4) transmission scan lines 221 of the transmission scan lines 221 (16 lines in FIG. 7A) required for imaging are selected. The pattern of the selected transmission scan lines 221 is set so as to have a substantially uniform density in the imaging region 120a. The 1/N transmission scan lines 221 (=reception scan lines 21a) selected by N scans are set so as not to overlap each other.

The control unit 106 sets the number of scans n to 1 to start scanning (step 504) and executes ultrasonic wave transmission/reception processing (steps 505 and 506). Specifically, under the control of the control unit 106, as a transmission process, the transmission unit 102 has a plurality of transmission scan lines 221 (FIG. 7A) designated by the transmission scan position determination unit 103 in the first scan. Then, the transmission signals are sequentially generated so that the ultrasonic waves 121 are sequentially transmitted to the ultrasonic probe 108 (step 505). Thereby, the ultrasonic wave 121 is sequentially transmitted from the ultrasonic probe 108 along the four transmission scanning lines 221, and the ultrasonic wave echo 122 from the imaging region 120a is received by the ultrasonic probe 108 at each transmission. The received signal is output.

Under the control of the control unit 106, as the reception process, the reception unit 104 selects the reception scanning line 21a at the same position as the transmission scanning line 221, and arranges the reception data for a plurality of points on the reception scanning line 21a. It is generated by phase addition processing or the like (step 506). The reception unit 104 stores the generated reception data in the area 22a of the memory 20 and also transfers it to the interpolation data generation unit 10.

The interpolation data generation unit 10 generates interpolation data as shown in FIG. 7B for points on the unselected reception scan line 21b among all reception scan lines 21 necessary for imaging (step 507). ). The generated interpolation data is stored (saved) in the area 22b of the memory 20 (step 508).

In step 509, the control unit 106 determines whether or not the number of scans n is 2 or more. If it is less than 2, n is incremented by 1 (step 510), the process returns to steps 505 to 508, and the second scan is performed. Is executed (step 510). At this time, the reception data and the interpolation data stored in the areas 22a and 22b of the memory 20 in the first scan are moved to the area 23 as past reception data.

In the second scan, as illustrated in FIG. 7A, the ultrasonic waves 121 are transmitted to the plurality of transmission scan lines 221 (four in FIG. 7A) different from those in the first scan, and the ultrasonic waves 121 are transmitted. The echo 122 is received, reception data is generated for the same selected reception scan line 21a as the transmission scan line 221, and is stored in the area 22a of the memory 20 (steps 505 and 506). Further, the interpolation data is generated by the interpolation data generation unit 10 for the unselected reception scan line 21b and stored in the area 22b of the memory 20 (steps 507 and 508).

In step 509 again, the control unit 106 determines whether or not the number of scans n is 2 or more, and since it is 2 or more, the process proceeds to step 511. Under the control of the control unit 106, the mixing coefficient calculation unit 30 determines that the interpolation data generation unit 10 has generated the interpolation data, and the past reception data stored in the area 23 of the memory 20 (for n=2 to 4). , Part of the interpolation data) is read (step 511). Then, the process proceeds to step 512, and under the control of the control unit 106, the index calculation unit 31 of the mixing coefficient calculation unit 30 determines the state of the read reception data value A in the past and the interpolation data value B obtained in the current scan. The index R indicating the closeness of is calculated by the above formula (1). The coefficient calculation unit 32 calculates the mixing coefficient C1 of the past received data value A and the mixing coefficient C2 of the interpolated data value B by the formula (2) based on the index R.

Further, under the control of the control unit 106, the mixing processing unit 40 performs the mixing processing on the past reception data value A and the interpolation data value B at the ratio of the mixing coefficients C1 and C2 according to the equation (3), and outputs the mixing data D. Get (step 513). The obtained mixed data is replaced with the interpolation data in the area 22b of the memory 20 and stored (step 514). As a result, mixed data obtained by mixing the last received data value A and the current interpolated data value B depending on how close the state of the point for which the interpolated data was obtained in this scan is from the previous scan. By obtaining D, the interpolated data can be replaced with the mixed data D.

When the number of scans is small (n=2 to 4), the interpolation data of the previous scan is stored in a part of the area 23 of the memory 20. Even when the data read from the area 23 is the interpolation data, the interpolation data generation unit 10 may mix the current interpolation data to obtain the mixed data, or use only the current interpolation data without mixing. Good. If the data stored in the area 23 is past mixed data, it is likely to be the same as the past received data generated by the receiving unit 104. Treated in the same manner, the mixed data with the current interpolation data is obtained.

Next, in step 515, under the control of the control unit 106, the image processing unit 107 causes the image processing unit 107 to receive the reception data of the reception scanning line 21a of the current scan and the mixed data of the reception scanning line 21b in the area 22 of the memory 20. (Or interpolation data) is used to generate a three-dimensional image (three-dimensional volume data) of the imaging region 120a and display it on the display device 122.

Then, returning to step 510, the control unit 106 performs the next scan. When the number of scans n exceeds N, the control unit 106 returns to the pattern of the transmission scan line 221 of the first scan again, repeats the scan in the same manner, and the operator gives an instruction to end the imaging via the UI 121. Repeat scan until there is.

According to the above operation, in the second embodiment, the mixing coefficient determined based on the closeness of the states of the interpolation data and the past reception data, the reception data on the non-selected reception scanning line 21b, and the interpolation data and the past reception data. Therefore, the image quality can be improved while suppressing the generation of false images, as compared with the case where the interpolation data and the past reception data are selectively used.

In the above description, the index R is obtained for each point (pixel) on the reception scan line 21b, but the unit for obtaining the index R is not limited to each pixel, and is a unit of a certain range (area) of voxels or planes. You may ask for each. That is, when calculating (determining) the mixing ratio, the mixing coefficient calculation unit 30 of the mixing unit 3 sets an area including the point for which the interpolation data is obtained and a plurality of points around it as the reception scanning line 21b, Based on the representative value of the interpolated data of a plurality of points in the area and the representative value of the past received data of a plurality of points in the area, the mixing coefficient (mixing coefficient) of the interpolated data and the past received data in this area May be determined. For example, in the case of voxels, a range of 3×3×3 cubes in the x, y, and z directions is set as an area, and a representative value or an average value of data in the area is used to calculate the index R. The mixing coefficients C1 and C2 obtained from the index R are applied to all pixels included in a 3×3×3 cubic area, and the past reception data value A and interpolation data value B for each pixel are calculated. Mix. In this case, the index R can be calculated in consideration of the state of a certain range (region) in which the pixel is included, rather than the case where the index R is calculated in pixel units, and thus the image quality can be improved. There is. Further, there is an advantage that the amount of calculation can be reduced by calculating the index R in a fixed range (region), rather than the case where the index R is calculated in pixel units.

The representative value of data in a certain range (area) of a voxel or plane is the average value of the interpolated data and received data for multiple points in the area, the interpolated data of multiple points in the area, and the barycentric coordinates of the received data. A data value or the like may be used. The barycentric coordinates can be obtained as follows. The coordinate vector of a point (pixel) in a voxel or plane area is Vi=(Xi,Yi,Zi) (where i is the number of each point (pixel) in the area, and if it is a 3×3 plane area) , I=1 to 9) and the data value (interpolation data value or received data value) of each point (pixel) is Bi, the center-of-gravity coordinate vector S is obtained by the following equation (4).
S=Σ(Vi*Bi)/Σ(Bi) (4)

It should be noted that the interpolation data value used in the calculation of the index R and the past reception data value may be the intensity of the data after phasing addition (luminance data of a three-dimensional image) or the waveform information, as described in the first embodiment. (Amplitude and phase information) may be used.

<<Embodiment 3>>
An ultrasonic imaging apparatus according to the third embodiment will be described.

The ultrasonic imaging apparatus of the third embodiment has the same configuration as the ultrasonic imaging apparatus of the second embodiment, but the configuration of the index calculation unit 31 is different from that of the second embodiment.

In the second embodiment, with respect to the point where the interpolation data is obtained, the index R of the state closeness between the current scan and the previous scan is obtained by the ratio between the interpolation data and the past data as in the formula (1). In 3, the difference amount is used. Although the smaller the difference amount is, the closer the state is, the reference value is used to appropriately represent the small amount, and the difference or ratio between the difference amount and the reference value is used as the index R. The reference value is determined based on the distribution information of the received data obtained from the entire imaging area 120a.

FIG. 8 is a block diagram showing a detailed configuration of the mixing coefficient calculation unit 30 according to the third embodiment. As shown in FIG. 8, the index calculation unit 31 includes a distribution calculation unit 33 and a reference value setting unit 34. The distribution calculator 33 calculates the distribution of the received data values of the entire imaging area 120a. The reference value setting unit 34 sets the reference value from the distribution of the reception data obtained by the distribution calculation unit 33.

Specifically, the distribution calculation unit 33 calculates the distribution of the entire received data value of the imaging region 120a of the current scan generated by the reception unit 104 in step 506 of the second embodiment. FIG. 9 is a graph showing an example of the distribution of received data values calculated by the distribution calculation unit 33. The horizontal axis represents the received data values and the vertical axis represents the number of data samples of the received data values. As shown in FIG. 9, the received data values are distributed with the received data value Dp as a peak, except for the 0 value. The reference value setting unit 34 sets, as the reference value S, a value having the smallest received data value in the range 90 in which the number of samples of received data is equal to or larger than a predetermined value. Alternatively, the reference value setting unit 34 sets the reception data value D1 at the point where the distribution of the reception data calculated by the distribution calculation unit 33 starts to rise, and the number of samples reaches the peak when the reception data value is closer to zero than the peak. The received data value at a point before the point (for example, the point at which the number of samples reaches a predetermined ratio (for example, 80%)) may be set to D2, and the reference value S may be set within the range of D1 to D2. Further, it is desirable that the reference value S within the range of D1 to D2 can be adjusted automatically or by the user.

The index calculation unit 31 calculates the index R using the reference value S obtained by the distribution calculation unit 33 and the reference value setting unit 34 and the following equations (5) and (6).

R=(S−d)/S (5)
d=|AB|... (6)
However, B is the interpolation data value obtained in the current scan, and A is the reception data value generated by the receiving unit 104 in the previous scan at the point where the interpolation data value B was obtained.

The index-based coefficient calculation unit 32 calculates the mixing coefficients C1 and C2 by the following equation (2) as in the second embodiment.

C1=R, C2=(1-R) (2)

The mixing processing unit 40 calculates the mixed data value D by the following equation (3) as in the second embodiment.

D=A*C1+B*C2 (3)

By using the index R defined by the above equations (5) and (6), the smaller the difference amount d between the interpolation data value B and the past reception data value A (the closer the state), the more the past in the mixed data D. The ratio of the reception data value A increases, and the ratio of the interpolation data value B increases as the state changes. At this time, as the reference value S, a value between the point D1 at which the distribution of the received data starts to rise and the point D2 before the peak is used. Does not occur, and the problem that the reference value S is too small and the amount of interpolation data increases and the effect of improving image quality is difficult to obtain does not easily occur. Therefore, an appropriate mixing coefficient can be calculated based on the real-time state of the imaging target 120, and it is possible to provide a high-quality three-dimensional image with no temporal unevenness in the image.

The other configurations and operations are the same as those in the second embodiment, and thus the description thereof is omitted.

<<Embodiment 4>>
In the ultrasonic imaging apparatus according to the first to third embodiments described above, the mixing coefficient calculation unit 30 reads from the interpolation data on the reception scan line 21b generated by the interpolation data generation unit 10 and the area 23 of the memory 20. A low pass filter may be applied to each of the past reception data on the reception scanning line 21b, and then the mixing coefficient may be calculated using both data.
It is generally known that the reception data of a plurality of points on the reception scanning line 21 include a strong and weak pattern such as a speckle pattern generated by the interference of ultrasonic waves. By applying the low-pass filter, it is possible to reduce the speckle pattern and the like peculiar to the ultrasonic data from the interpolated data and the past data on the reception scanning line 21 and convert the data into the data that smoothly changes in the reception scanning line 21b direction. it can. As a result, the variation peculiar to the ultrasonic data is reduced, so that the mixing coefficient calculation unit 30 can calculate the mixing coefficient without being influenced by the variation peculiar to the ultrasonic data. Therefore, a high-quality three-dimensional image can be provided.

<<Fifth Embodiment>>
The fifth embodiment provides an ultrasonic imaging apparatus capable of calculating the mixing coefficient by excluding the influence even when the imaging target 120 is a heart that repeatedly repeats the same movement. Therefore, the mixing coefficient calculation unit 30 and the mixing processing unit 40 are configured to read, as past reception data, past reception data obtained at the timing of the same time phase as the current scan from the area 23 of the memory 20.

Specifically, the configuration of the ultrasonic imaging apparatus according to the fifth embodiment will be described with reference to FIG. FIG. 10 is a block diagram showing the configuration of the ultrasonic imaging apparatus 111 of the fifth embodiment. As shown in FIG. 10, the transmission unit 102 is connected to a biosignal meter 12 such as an electrocardiograph attached to the imaging target 120. As a result, under the control of the control unit 106, the transmission unit 102 receives a biological signal such as an R wave of an electrocardiogram, synchronizes with the biological signal, and transmits the transmission signal to the ultrasonic probe 108 in a plurality of time phases. Output. As a result, the ultrasonic probe 108 transmits the ultrasonic wave 121 in synchronization with the time phase of the heart.

The area 23 of the memory 20 that stores past received data includes areas (temporal area) 23a to 23d that store past data for each time phase of the imaging target 120. The past received data of each time phase is stored in each of the areas 23a to 23d. Therefore, the region 23 stores past received data for one heartbeat (one cycle) of the heart.

Under the control of the control unit 106, the mixing coefficient calculation unit 30 sets the past reception data at the same point as the interpolation data received from the interpolation data generation unit 10 in the current scan to the same time in the regions 23a to 23b. A region in which the past reception data of the phase is stored is selected and read, and the mixing coefficient is calculated using the interpolation data and the past reception data. As a result, even if the heart is moving violently in real time, the time phases when the interpolation data and the received data are obtained are the same, which means that the substantial form of the heart is not moving. That is, it is possible to exclude the periodical change in the state of the heart and calculate the mixing coefficient according to the closeness of the state due to other reasons. Therefore, it is possible to obtain mixed data in which the received signals obtained in the past in the actual scan are mixed at a higher ratio, so that the image generated by the image processing unit 107 can have high image quality.

Further, even when the state of the heart locally changes due to a disease such as an irregular pulse, in the first to fifth embodiments, the calculation of the mixing coefficient and the mixing process are performed using the interpolation data and the past data for each pixel of the imaging region 120a. Since the mixed processing of the received data is performed, it is possible to provide a spatially smooth and uniform image quality, which is unlikely to be affected by the local change of the imaging target due to arrhythmia or the like.

12... Biological signal meter, 20... Memory, 21... Reception scanning line, 22... Area for storing current reception data, 23... Area for storing past reception data, 31... Index calculating unit, 32... Coefficient based on indexes Calculation unit, 33... Distribution calculation unit, 34... Reference value setting unit, 61... Screen, 100... Ultrasonic imaging device, 108... Ultrasonic probe, 102... Transmission unit, 103... Transmission scan position determination unit, 104... Receiving unit, 105... Signal processing unit, 120... Imaging target, 120a... Imaging region, 221... Transmission scanning line

Claims (12)

An ultrasonic probe that transmits ultrasonic waves to the imaging target, receives the ultrasonic waves returned from the imaging target for each transmission, and converts the ultrasonic waves into a reception signal.
Reception data for each of a plurality of points on the selected reception scan line is set by setting a number of reception scan lines necessary for imaging in the imaging area of the imaging target, selecting a predetermined number of the reception scan lines. A receiving unit for generating the received signal from the received signal,
A memory for storing the reception data generated by the reception unit,
By interpolating the reception data generated by the reception unit, an interpolation corresponding to the values of the reception data for a plurality of points on one or more reception scan lines among the reception scan lines not selected by the reception unit. An interpolation data generation unit for generating a data value B by calculation,
At the same point as the point where the interpolation data value B is obtained, the past reception data value A generated from the past reception signal by the reception unit is read from the memory, and the interpolation data value B and the past And a mixing unit that mixes the received data value A to generate a mixed data value D and uses the value as the point ,
From the interpolated data value B and the past received data value A, the mixing section calculates an index value R indicating the closeness of these values, and obtains mixing coefficients C1 and C2.
C1=R, C2=(1-R)
Calculated by
The mixed data value D
D=A*C1+B*C2
An ultrasonic imaging apparatus characterized by: The ultrasonic imaging apparatus according to claim 1 , wherein the index value R is a ratio A/B of a value between the interpolation data value B and the past reception data value A. Sound wave imaging device. The ultrasonic imaging apparatus according to claim 1 , wherein the index value R is obtained in advance as a difference amount | AB | of a value between the interpolation data value B and the past reception data value A. The ultrasonic imaging apparatus is characterized by a difference or a ratio with the reference value S. The ultrasonic imaging apparatus according to claim 3 , wherein the mixing unit determines the reference value S based on a distribution of values of the reception data obtained by the reception unit. Imaging device. The ultrasonic imaging apparatus according to claim 1, wherein the mixing unit sets an area including the point for which the interpolation data is obtained and a plurality of the points around the interpolation data as the reception scanning line, and includes the area in the area. The index value R is calculated based on a representative value of the interpolated data value B of a plurality of points included in the area and a representative value of the past received data value A of the plurality of points included in the area. An ultrasonic imaging apparatus, characterized in that the mixing coefficients C1 and C2 in a region are determined. The ultrasonic imaging apparatus according to claim 5, the representative value of the interpolated data value B, the average value of the interpolation data values B for a plurality of the points in the area, or in multiple in the area an interpolated data value of the center of gravity coordinates of the interpolation data values B of the point, the representative value of the received data value a, the average value of the received data values a for a plurality of the points in the area, or the area The ultrasonic imaging apparatus is a received data value of a barycentric coordinate of the received data value A for a plurality of the above points. The ultrasonic imaging apparatus according to claim 1, wherein the reception data value A is intensity or waveform information of a post-phasing addition signal obtained by performing a phasing addition on the reception signal so as to focus the point. An ultrasonic imaging device characterized by: The ultrasonic imaging apparatus according to claim 1, wherein the ultrasonic probe synchronizes with a periodic movement of the imaging target to generate ultrasonic waves for each of a plurality of time phases set during the cycle. Send,
The mixing unit, for the same point as the point for which the interpolation data value B is obtained, the reception data generated from the reception signal obtained by the reception unit for the ultrasonic waves transmitted in the same time phase in the past, An ultrasonic imaging apparatus, which reads out as past reception data value A from the memory and mixes it with the interpolation data value B. The ultrasonic imaging apparatus according to claim 8 , wherein the memory has a plurality of areas for respectively storing the reception data for each of the plurality of time phases,
The mixing unit selects, from the plurality of regions, the region having the same time phase as the time phase at which the reception unit generated the reception data this time, and the past reception data stored in the selected region. An ultrasonic imaging apparatus characterized by reading a value A. The ultrasonic imaging apparatus according to claim 1, wherein the reception data generated by the reception unit from the reception signal received by the ultrasound probe this time, and the mixed data value D mixed by the mixing unit. An ultrasonic imaging apparatus, further comprising an image processing unit for generating an image of the imaging target by using the image processing unit. A reception unit of the ultrasonic imaging apparatus selects a predetermined number of reception scan lines necessary for imaging, receives and stores reception data generated for each of a plurality of points on the selected reception scan line. Memory and
By interpolating the reception data generated by the reception unit, an interpolation corresponding to the values of the reception data for a plurality of points on one or more reception scan lines among the reception scan lines not selected by the reception unit. An interpolation data generation unit for generating a data value B by calculation,
At the same point as the point where the interpolation data value B is obtained, the past reception data value A generated from the past reception signal by the reception unit is read from the memory, and the interpolation data value B and the past And a mixing unit that mixes the received data value A with the value of the point ,
From the interpolated data value B and the past received data value A, the mixing section calculates an index value R indicating the closeness of these values, and obtains mixing coefficients C1 and C2.
C1=R, C2=(1-R)
Calculated by
The mixed data value D
D=A*C1+B*C2
Signal processing apparatus according to claim <br/> be calculated by. Receiving a reception signal of an ultrasonic wave returned from the imaging target to which the ultrasonic wave is transmitted, setting the number of reception scanning lines necessary for imaging in the imaging region of the imaging target, and setting a predetermined number of the reception scanning lines. Selecting a number to generate reception data for each of a plurality of selected points on the reception scan line from the reception signal,
Storing the received data in a memory,
By interpolating the received data , an interpolation data value B corresponding to the value of the received data for a plurality of points on one or more of the unselected receiving scan lines is generated by calculation.
For the same point and the points obtained the interpolated data value B, the previously received data value A generated from the past received signal read from said memory, from said previously received data value A and the interpolated data value B , The index value R representing the closeness of those values is calculated, and the mixing coefficients C1 and C2 are calculated.
C1=R, C2=(1-R)
Calculated by
The mixed data value D
D=A*C1+B*C2
Calculated by
A signal processing method for an ultrasonic imaging apparatus, wherein an image of the imaging target is generated using the received data and the mixed data value D.

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