Ultrasonic aperture composite method and device

Abstract

The present invention discloses an ultrasonic aperture compounding method and a device thereof. The method of the present invention only requires two scans. The first scan uses the middle array element symmetrically defined by the scanning line for transmission, and uses the same array element for reception; the transmission of the second scan is the same as the first scan, but the reception of the second scan is adjusted to the array elements on both sides for reception, and the near-field data in the initial reception is invalidated. The present invention can effectively solve the influence of the existing near-field switch switching on the image, and can make the receiving channel achieve an effect of twice the actual physical channel, thereby achieving low cost and high performance. The present invention can ensure the stability of the sound field by a fixed transmission and switching of the middle / edge channel reception, so that the aperture compounding effect is basically consistent with the actual double channel effect. The present invention cleverly utilizes the small near-field receiving aperture, and realizes the connection switching from the transmitting to the receiving array element by invalidating the abnormal data during this period, thereby ensuring the overall performance.

Description

Technical Field

[0001] The present invention relates to ultrasonic diagnostic equipment, to cost-effective ultrasonic diagnostic equipment (achieving more channel comprehensive effects through less hardware), and in particular to an ultrasonic aperture compounding method and a device thereof. Background Art

[0002] Ultrasonic imaging technology has been widely used. By scanning a specific area with an acoustic beam and performing AD, beam synthesis, and signal processing on the backscattered echo signal, a brightness signal image, commonly known as a B (Brightness) hyperimage, can be obtained. If a certain scanning area is scanned multiple times in succession, the blood flow signal, commonly known as a C (color) image, can be obtained by calculating the frequency shift caused by the Doppler effect through the changes between the multiple times. In addition, there are also imaging methods such as energy and spectrum, which are essentially extended applications of these two modes.

[0003] Regardless of the method, beamforming is the core processing link. This module focuses the channel signal after AD through time shift, and performs weighted merging based on the characteristics of the sound field, and finally converts the two-dimensional plane sound field information into a one-dimensional signal stream, that is, forming a sound beam. The formation of the sound beam can greatly simplify the subsequent signal processing and image processing, and transform the ultrasound system from spatial information processing to a simple mathematical transformation of line-by-line processing.

[0004] With the increasing number of the above functions, as well as the continuous improvement of clinical image performance and the increasing requirements for cost control, contradictory functions such as multi-beam and aperture compounding appear at the same time. The goal of multi-beam is to obtain more beams at the same time, so that the frame rate of the system can be improved while basically maintaining the image quality. The cost is that the parallel processing requirements of the system are increased, which has higher requirements for software and hardware performance, but the overall benefits are greater, so it has been widely used. Aperture compounding is a way to reduce costs. Conventional scanning is to form one or more beams by transmitting once and receiving once, and all channels participate each time; while aperture compounding is to form one or more beams by transmitting twice and receiving twice, and the two transmissions are the same but the receiving channels are different, and then the results are linearly added to achieve the effect of a maximum of 2 times the physical channels. This method can achieve the comprehensive performance of nearly twice the physical channels without increasing the hardware cost, but it will sacrifice the system frame rate.

[0005] like Figure 2 As shown in the figure, this is a method proposed by Chinese patent CN100450443C. Its transmission remains unchanged (using the same transmission), but the reception is divided into left and right aperture reception. This method is theoretically feasible and solves the problem of Figure 3The problem of two different transmissions and asymmetric sound fields. However, in actual applications, it takes time to switch to the receiving array element after transmission, especially in the case of deflection. The transmission experience is longer, which will cause a longer time, corresponding to the impact of deeper distance. This solution will cause a significant image performance degradation in the near-field image; but after the switching period, it can still achieve or approach the effect of 2 times the physical aperture. In actual application, it is necessary to use normal transmission in the near field first, but only receive data during the switching period, and then use this data to compensate for the near-field anomaly during aperture compounding (because the transmission and reception use different array element connections, it is necessary to switch the connection from the array element to the channel after the transmission is completed. Although the high-speed switch can be achieved at the ms level, this still causes the echo signal to be disordered during the switching period in the near field. Therefore, in actual use, it is necessary to add a shorter receiving channel scan that is the same as the transmission to compensate for the near-field abnormal area of ​​the left and right reception). However, the disadvantage is that the increase in the entire time loss will further sacrifice the frame rate, and traces are likely to appear at the splicing place. Therefore, on a system with high performance requirements, it cannot meet the actual requirements. Summary of the invention

[0006] In view of the shortcomings and deficiencies of the prior art, the object of the present invention is to provide an ultrasonic aperture compound method. The present invention can effectively solve the near-field anomaly problem of the prior art, and only requires two scans. Figure 4 As shown in the figure, the first scan of each scan line will use the symmetrical transmission of the scan line definition position and use the same receiving array element for reception; the transmission of the second scan is the same as the first, but the reception is adjusted to the array elements on both sides. In the early stage of reception, the connection between the array element and the channel will still change, which will cause echo anomalies, but because the receiving aperture changes with depth, the array elements on both sides do not actually need to work at this time. In this way, the receiving signal in this time period is invalidated through the receiving parameters, and the switch switching can be completed in this time period to ensure the overall performance.

[0007] Another object of the present invention is to provide an ultrasonic aperture composite device.

[0008] The technical solution of the present invention is as follows:

[0009] An ultrasonic aperture compound method only requires two scans. The first scan uses the middle array element symmetrically defined by the scan line for transmission and the same middle array element for reception. The transmission of the second scan is the same as the first, but the reception of the second scan is adjusted to the array elements on both sides and the near-field data at the initial reception is invalidated.

[0010] The specific steps of the method are as follows:

[0011] (1) Calculate the position of the scan line line by line based on the position of the first scan line;

[0012] (2) Connecting the system physical receiving channel to the intermediate array element selected in this step, transmitting and receiving similarly to normal scanning, obtaining echo data C and caching it;

[0013] (3) At the same position, keep the middle array element connected to the system physical receiving channel and transmit the second scan. The relevant parameters of the transmission are exactly the same as those of the first scan.

[0014] (4) After all valid channels have finished transmitting, the system physical receiving channels are connected to the array elements on both sides.

[0015] (5) After the array elements on both sides receive the echo S, they add it point by point to the echo data C to obtain the echo data of a one-line aperture composite.

[0016] Furthermore, the intermediate array elements are array elements with the same number of channels and symmetrical on both sides of the scan line. For example, when the scan line of a 16-element 4-channel system is between 5 and 6 array elements, the intermediate array elements are 4 to 7 array elements.

[0017] The two side array elements are array elements with 1 / 2 channel number expanded on both sides of the middle array element. For the same example above, the two side array elements are 2 / 3 and 8 / 9 array elements.

[0018] Furthermore, in step (1): according to the position of the first scan line, the intermediate array element connections to be used are calculated line by line, and the number of the intermediate array elements is equal to the physical receiving channels of the system;

[0019] Furthermore, in step (4), the apodization coefficients from the beginning of the connection between the array elements on both sides and the physical receiving channel of the system to the completion of the connection are set to 0, that is, the near-field abnormal echo data of the second scan can be invalidated. This processing can protect the effectiveness of the function without affecting the near-field image quality.

[0020] Furthermore, after step (5), after a line of data is completed, it is necessary to determine whether it is the last line of the frame. If so, the frame ends. Otherwise, the line number is increased and the scan line position is adjusted according to the design to continue to the next line. The above process is repeated until the entire frame is completed.

[0021] An ultrasonic aperture composite device comprises a control structure, a front end, a signal processing structure and an image processing structure, wherein the control structure is respectively connected to the front end, the signal processing structure and the image processing structure; the front end can be connected to multiple probes, and under the control of the control structure, completes specific frequency transmission, receives echo signals for AD conversion, beam synthesis and finally outputs RF signals; the signal processing structure comprises B signal processing, C signal processing, PW / CW signal processing and Elasto signal processing structures; and the signal processing structure is connected to the image processing structure.

[0022] The advantages of the present invention are as follows:

[0023] The aperture compounding method proposed in the present invention can effectively solve the influence of the existing near-field switch switching on the image.

[0024] The aperture compounding method proposed in the present invention can make the receiving channel achieve an effect that is twice that of the actual physical channel, thereby achieving low cost and high performance.

[0025] The aperture compounding method proposed in the present invention can ensure the stability of the sound field by a fixed transmission and switching middle / edge channel reception mode, so that the aperture compounding effect is basically consistent with the actual double channel effect.

[0026] The aperture compounding method proposed in the present invention cleverly utilizes the smaller near-field receiving aperture and invalidates the data during this period to achieve the connection switching from the transmitting to the receiving array element, thereby ensuring the overall performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the color ultrasound system architecture diagram;

[0028] Figure 2 is a schematic diagram of an aperture composite scheme shown in the background technology;

[0029] Figure 3 It is a schematic diagram of an aperture composite scheme designed by the applicant;

[0030] Figure 4 It is a schematic diagram of the ultrasonic aperture composite scheme of the present invention;

[0031] Figure 5 It is a schematic diagram of the aperture compound scanning process of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0033] like Figure 1 As shown, the ultrasonic aperture compound device of the present invention generally includes a control structure (operating system), a front end, a signal processing structure and an image processing structure, and the control structure is connected to the front end, the signal processing structure and the image processing structure respectively. Among them, the front end is connected to the probe, and completes the specific frequency transmission under the control of the control structure, and receives the echo signal for AD conversion, beam synthesis and finally outputs the RF signal; the apodization is a very important processing link in the beam synthesis, and its purpose is to give different channels different weights to achieve the effect of suppressing side lobes, thereby improving tissue morphology, including spatial resolution improvement and noise improvement. The multiplexer and connector are used to connect multiple probes.

[0034] The signal processing structure includes B signal processing, C signal processing, PW / CW signal processing and Elasto signal processing structure. The signal processing structure is connected with the image processing structure.

[0035] Among them, the RF signal output by beam synthesis is processed by B signal to form a B image. During 4D scanning, the real-time moving B image finally forms volume data, and 4D imaging is realized through 3D reconstruction. Whether it is B image or 4D imaging, the image results can be measured and applied to various functions. Among them, the RF signal output by beam synthesis is processed by C to form a color image, that is, blood flow imaging, and its results can also be processed, measured and applied in 4D. Among them, the PW and CW images of the RF signal output by beam synthesis are processed by PW / CW, and the results can also be measured and applied, especially the PW / CW measurement speed is a quantitative value, which has great clinical value. Among them, Elasto elastic imaging is also a widely used function now. This function has special requirements for emission, but the basic processing flow is similar. The above processing structures are finally fused and displayed through system control, that is, various combinations such as B+C, B+PW (CW) and three functions can be realized.

[0036] like Figure 3 As shown, the applicant has designed a most intuitive aperture compounding method, which is to double the aperture to the left and right of the normal scanning center. During normal scanning, we usually use the scanning line as the center, allocate half of the maximum supported aperture to the left and right, and then use parameters to control the use of different actual apertures for transmission and reception at different positions. The transmission and reception apertures are usually different. However, during normal scanning, the array elements corresponding to the maximum apertures of transmission and reception are completely identical, and then different actual scanning line positions are achieved through focusing parameters. Figure 3 In the aperture compounding scheme shown, according to the definition of the transmitting center, an aperture is set to the left and right according to the maximum aperture supported by the system. When the system scans, it first transmits and receives with the left aperture, and then transmits and receives with the right aperture. The received signals are combined to achieve aperture compounding, which can support twice the physical transmitting aperture and twice the physical receiving aperture. It should be noted that whether it is scanning on the left or right side, the focus center is the same, that is, the actual theoretical transmitting or receiving scanning line position. When scanning on each side of this method, the transmitting and receiving use exactly the same array elements, so there is no problem of switching, and there is no transient state of receiving array element switching. However, its disadvantage is that its transmitting sound field is asymmetric and different on the left and right, so its imaging effect will be significantly weaker than the actual 2 times physical channel result, especially when the scanning is deflected.

[0037] Figure 4This is an ultrasonic aperture composite method proposed by the present invention. The traditional axisymmetric left and right expansion is adjusted to a scheme of adding half the number of apertures of the maximum physical aperture on both sides of the normal physical aperture, while the transmission maintains the same array element connection method as normal scanning. The specific method scanning is divided into two steps. The first scan is exactly the same as the normal scan. The transmission is axisymmetric and half of the maximum physical aperture is expanded to the left and right for scanning. The transmission and reception are the same. The transmission of the second scan still uses the same transmission aperture and parameters as the first scan to maintain the symmetry of the transmitted sound field. After all array elements are transmitted, the reception of the second scan is switched to the array elements on both sides of the normal scanning physical array elements, and the array element connection support of half the number of physical channels of the system is added on both sides. Taking 16 array elements and 4 channels as an example, when the center of the scan line is between 5 / 6 array elements, the array elements for transmission and reception are usually 4~7, which we call middle array elements; and on both sides of the middle array element, half of the number of channels are added, that is, 2 / 3 and 8 / 9 are the array elements on both sides (or edge array elements). When the scan line reaches the leftmost or rightmost side, the array elements on both sides may be missing (such as Figure 4 As shown in the figure). During the second scan, the switching of the receiving array elements will cause data anomalies in the near field, affecting the imaging results. However, since the ultrasonic aperture gradually increases with depth, only the result of the first scan is needed to meet the image requirements during the nearest field reception. Therefore, the near field data of the second scan can be invalidated. In this way, the image effect of 2 times the physical aperture can be achieved without near field anomalies.

[0038] Figure 5 The process of scanning an image frame according to the method of the present invention is shown:

[0039] When a frame begins, the system starts from the first scan line position and calculates the intermediate array element connections that should be used based on the first scan line position. The number is equal to the system's physical receiving channels.

[0040] First, connect the system receiving channel and the intermediate array element selected in this step, and perform transmission and reception similar to normal scanning. The obtained echo data C needs to be cached.

[0041] Next, at the same position, the array element and the channel are connected to perform a second scan transmission, and the relevant parameters of the transmission are exactly the same as those of the first scan transmission.

[0042] Then, when all valid channels have finished transmitting, the system channels are connected to the edge physical channels, that is, the array elements on both sides (specifically, Figure 4 as described above, and the text description in the previous paragraph).

[0043] At this point, it should be noted that: in this process, the system is actually receiving, so until the receiving array element is fully connected to the physical channel, the system echo is abnormal, and the subsequent echo is normal aperture composite edge supplementary data. Since the system apodization parameters will change with depth, the aperture is small in the nearest field. As long as the apodization coefficient is ensured to be 0 before the receiving connection is completed, the abnormal echo in the near field can be invalidated.

[0044] Regarding effective channels: Take 16 array elements and 4 channels as an example. If 2 channels are transmitted, then the effective channel is 2; of course, it can also be 4. If the channel is 16, there are more choices. Transmission requires focusing, which means that the time for all array elements to reach a point is the same. Because the speed of ultrasound is 1540, the farther the distance is, the earlier the transmission should be. Therefore, the more effective channels are transmitted, the longer the total transmission time will be.

[0045] Then, after the echo S is received by the array elements on both sides, it is added point by point with the echo data C to obtain the echo data of a one-line aperture composite, which can be further processed in the conventional way.

[0046] Finally, after one line of data is completed, it is necessary to determine whether it is the last line of the frame. If it is, the frame ends. Otherwise, the line number is increased and the scan line position is adjusted according to the design to continue to the next line. Repeat the above process until a frame is completed.

[0047] When there is color or PW mode scanning, different modes (B / color / PW, etc.) may be inserted into a complete frame. At this time, modify the frame definition to a continuous segment, or use Figure 5 process execution.

[0048] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any form, and any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. An ultrasonic aperture compound method, characterized in that: The method only requires two scans. In the first scan, the middle array element with symmetrical position defined by the scan line is used for transmission, and the same middle array element is used for reception. The transmission of the second scan is the same as the first scan, but the reception of the second scan is adjusted to the array elements on both sides for reception and the near-field data at the initial reception stage is treated as invalid. The middle array element is an array element with the same number of channels as the array element on both sides of the scanning line, which is symmetrical; the two side array elements are array elements with 1 / 2 number of channels expanded on both sides of the middle array element; The steps of the method are as follows: (1) Calculate the position of the scan line line by line based on the position of the first scan line; (2) Connect the system physical receiving channel to the intermediate array element selected in this step, perform normal scanning for transmission and reception, obtain echo data C and cache it; (3) At the same position, keep the middle array element connected to the system physical receiving channel and transmit the second scan. The relevant parameters of the transmission are exactly the same as those of the first scan. (4) After all valid channels have finished transmitting, the system physical receiving channels are connected to the array elements on both sides. (5) After the array elements on both sides receive the echo S, they add it point by point to the echo data C to obtain the echo data of a one-line aperture composite.

2. An ultrasonic aperture compound method according to claim 1, characterized in that: The step (1): according to the position of the first scan line, the intermediate array element connection to be used is calculated line by line, and the number of the intermediate array elements is equal to the physical receiving channels of the system.

3. The ultrasonic aperture compounding method according to claim 1, characterized in that: The step (4): setting the apodization coefficient from the beginning of connecting the array elements on both sides to the system physical receiving channel to the end of the connection to 0, that is, the near-field abnormal echo data of the second scan can be invalidated.

4. The ultrasonic aperture compound method according to claim 1, characterized in that: After step (5), when one line of data is completed, it is necessary to determine whether it is the last line of the frame. If so, the frame ends. Otherwise, the line number is increased and the scan line position is adjusted according to the design to continue to the next line. The above process is repeated until the entire frame is completed.

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