KR20020060573A - Transmitting focusing and beam forming method and apparatus for providing adaptive scaling data - Google Patents

Abstract

The present invention relates to an adaptive transmission and reception focusing method and apparatus. The reception focus according to the present invention focuses a plurality of preliminary scan line data by applying an adaptive delay profile to ultrasonic signals reflected from a group of ultrasonic pulses and received by the transducer array, and combines the plurality of preliminary scan line data. Generate single scanline data. The adaptive transmission focusing method according to the present invention is characterized in that a plurality of delay profiles are applied according to the propagation speed of ultrasonic waves in a target region in which an ultrasound image is to be formed. As described above, when a single delay profile is used, errors in transmission and reception convergence caused by different media characteristics can be reduced, and thus a clear ultrasound image reflecting characteristics of the media can be realized.

Description

TRANSMITTING FOCUSING AND BEAM FORMING METHOD AND APPARATUS FOR PROVIDING ADAPTIVE SCALING DATA}

The present invention relates to transmission focusing and reception focusing in an ultrasound imaging system, and relates to a transmission focusing and reception focusing apparatus and method for forming adaptive scan line data using a plurality of delay profiles by reflecting characteristics of a medium to be imaged. will be.

As is well known, an ultrasound imaging system using a phased array includes an array 10 of multiple transducers. 1A and 1B show a conventional transmission focusing device and a reception focusing device using such a phased array. As shown in Fig. 1, such a system includes a plurality of channels, each channel including a transmitter and a receiver connected to each transducer. Transducers of the transmitter serve to apply a group of ultrasonic pulses to a target object, for example, a human body. In order to focus the transmitted ultrasonic energy at a desired point in the object, the delay profile of the ultrasonic pulses is determined so that the pulse constructively interferes at the desired point, and each transducer outputs a pulse at an appropriate time point according to this predetermined delay profile. do.

Based on Figure 1a looks at the generation process of the ultrasonic pulse according to the prior invention. First, when the trigger pulse notifies the start of the transmission of the ultrasonic pulse, the delay circuit 1 applies an appropriate delay to each transducer array of the transmitter. On the basis of the applied delay time, the transmission waveform stored in the waveform table 3 is read, amplified by the power amplifier 5, and applied to each transducer array to transmit ultrasonic pulses.

The pulses are reflected back to the transducer array 10 through various structures in the object, and receive and focus the reflected signals to form an ultrasound image. A method of receiving and focusing a reflected signal based on FIG. 1B is as follows.

Ultrasonic energy reflected from the object reaches a different time for each array element. The received signal is temporarily stored in the memory (FIFO) 30 via the analog / digital converter (A / D) 20 and undergoes a beam forming process. The digital signals stored in the memory 30 are all summed after having undergone a suitable delay to focus at a desired point by a delay controller 40. As the focus point progresses in the depth direction, the value of the delay is constantly changing so that the focus is achieved. Thereafter, the ultrasound image is displayed through the display device 70 through the memory (FIFO) 50 and the demodulator 60.

The delay profile applied during transmission focusing and reception focusing is determined by the propagation speed of the ultrasonic pulse in the medium. In other words, assuming that the transmission ultrasound reaches a certain depth of the medium and is reflected back, the delay profile of the focusing and receiving focus is determined. The rate of passage of the medium of the transmitted ultrasound is determined by the characteristics of the medium to which the ultrasound is applied. For example, when the medium is a human body, the propagation speed of the ultrasound has a value of 1460 m / s in fat, 1555 m / s in liver, 1560 m / s in blood, and 1600 m / s in muscle.

In practice, the medium through which the ultrasound proceeds is not uniform, and the speed of propagation changes with the depth of the medium. However, in the related art, since the transmission focusing and the reception focusing have been performed assuming a uniform medium, the actual delay value experienced by the ultrasonic signal according to the change of the medium does not reflect the error of transmission focusing and reception focusing due to the change of the medium. Cause problems.

As described above, in the conventional ultrasound imaging system assuming a uniform medium, errors in focusing and reception focus occur according to the change of the actual medium. Therefore, accurate transmission convergence and reception convergence are not achieved, resulting in distortion of the image. In order to solve this problem, there is a need for a method using a delay profile reflecting the actual propagation speed of ultrasonic waves in consideration of the characteristics of the medium.

In order to focus the scanning line data by applying a plurality of delay profiles, a criterion for determining the accuracy of the reception focus and a method of dividing a target area for forming an ultrasound image according to the characteristics of the medium are required if the reception focus is not accurate. Do. The present invention provides an ultrasound system for generating accurate focusing data of each part of a partitioned area by using a criterion for dividing a target area and determining accuracy of reception focusing.

Adaptive reception focusing method according to an aspect of the present invention for the above object

In the method for receiving and focusing the scanning line data in the ultrasound imaging system,

a. Transmitting and concentrating an ultrasound signal to a target area in which a plurality of transducers form an ultrasound image;

b. Receiving and condensing the reflected ultrasonic signals received by the plurality of transducers according to a plurality of delay profiles to form a plurality of preliminary scan line data;

c. Combining the plurality of preliminary scan line data to form scan line data

Characterized in that it comprises a.

Receiving focusing device according to another aspect of the present invention

An apparatus for focusing scanning line data in an ultrasound imaging system,

a. Means for focusing ultrasound signals on a plurality of transducers to a target region for forming an ultrasound image;

b. Means for focusing the reflected ultrasound signals received at the plurality of transducers according to a plurality of delay profiles to form a plurality of preliminary scan line data;

c. Means for combining the plurality of preliminary scan line data to form scan line data

Characterized in that it comprises a.

In order to focus the transmission in consideration of the propagation speed of the actual ultrasonic wave within the object to be imaged, a plurality of delay profiles corresponding to the actual propagation speed should be generated, and the transmission focus should be performed by applying the plurality of delay profiles, respectively.

In order to solve this problem, the transmission focusing method according to one aspect of the present invention

Transmitting and concentrating a group of ultrasonic pulses by applying a plurality of delay profiles according to propagation speeds in a target region in which an ultrasound image is to be formed;

Transmitting the focused ultrasound pulse group

Characterized in that it comprises a.

In the transmission focusing method, the focusing of the group of ultrasonic pulses may include:

For each of the ultrasonic pulses belonging to the group of ultrasonic pulses,

Applying each of the plurality of delay profiles;

Generating a plurality of waveforms from waveform data corresponding to each of the plurality of delay profiles;

Combining the generated plurality of waveforms

Characterized in that it comprises a.

1A is a diagram illustrating an embodiment of a transmission focusing apparatus using a conventional phased array.

Figure 1b is a view showing an embodiment of a reception concentrating device using a conventional phased array.

2 is a diagram illustrating an embodiment of an ultrasound imaging system performing beam focusing in parallel using a plurality of delay profiles according to the present invention;

3 is a diagram illustrating a structure of a plurality of preliminary scan line data focused in parallel in one embodiment of the present invention shown in FIG.

4 is a diagram illustrating an embodiment of an ultrasound imaging system that sequentially performs beam focusing using a plurality of delay profiles according to the present invention.

FIG. 5 is a diagram illustrating a structure of a plurality of preliminary scan line data focused in sequence in one embodiment of the present invention shown in FIG. 4. FIG.

FIG. 6 is a diagram illustrating a structure of a scan line combining unit illustrated in FIGS. 2 and 4.

7 is a view showing an embodiment of an apparatus for extracting a high frequency component of a scanning line to determine the accuracy of the reception focus.

FIG. 8 is a diagram illustrating a method of dividing a scanning line by a hierarchical method in dividing a target area to combine overlapping-focused scanning line data to form adaptive scanning line data; FIG.

FIG. 9 is a diagram illustrating an embodiment of dividing a scan line using edge detection in dividing a target area to combine overlapping and focused scan line data to form adaptive scan line data; FIG.

10 is a flowchart illustrating a process of generating adaptive scan line data by applying a plurality of delay profiles.

11 is a block diagram illustrating an embodiment of a transmitter for adaptive transmission focusing by applying a plurality of delay profiles according to the present invention.

FIG. 12 is a block diagram illustrating an embodiment of a receiver for generating scan line data when using adaptive transmission focus according to the present invention. FIG.

FIG. 13 is a block diagram illustrating another embodiment of a receiver for generating scan line data when using adaptive transmission focus according to the present invention. FIG.

<Code Description of Main Parts of Drawing>

210, 400: delay controller

240, 430: scan line synthesis section

<Receiving Focusing Device>

The present invention uses a delay profile that reflects the actual characteristics of the medium, so that accurate reception convergence can be achieved even when the characteristics of the medium change.

The speed of propagation along the depth of the medium will not be constant at all depths. Therefore, it is very difficult to generate a delay profile by reflecting all the speed changes according to the change of the medium, and perform the reception focus using the delay profile. In fact, the distribution of the medium in the object to be imaged can be largely grouped into several kinds. Assuming a grouped medium, ultrasound can be transmitted from the transducer array to calculate the delay time to reach a predetermined depth and return back. Knowing the delay time, the average propagation velocity at which the ultrasonic waves pass to a predetermined depth can be obtained, and the delay profile according to the depth can be calculated using the average propagation velocity of the ultrasonic waves.

However, in the case of forming the ultrasound image, it is most likely that the characteristics of the medium through which the ultrasound propagates are not known in advance. Accordingly, in the present invention, a predetermined number of delay profiles are applied to receive and condense preliminary scan line data corresponding to each delay profile, determine the accuracy of the preliminary receive focused data, and combine the most accurate preliminary receive focused data to be adaptive. Generate scan line data.

The accuracy of reception focusing is determined for each determination region, which is a region obtained by dividing the target region to be imaged by a predetermined criterion. For each determination region, the accuracy of the reception convergence of the preliminary data focused by each delay profile is determined, and the determination region is further divided or the reception focused data is synthesized based on the accuracy of the reception concentration. The division of the determination region is repeated until all divisions of the determination region satisfy a predetermined accuracy.

Hereinafter, a reception focusing apparatus and method according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 illustrates an embodiment of an ultrasound imaging system performing focusing in parallel using a plurality of delay profiles according to the present invention. In the embodiment of FIG. 2, the plurality of preliminary scan line data are focused in parallel using delay profiles assuming four propagation speeds V ₀ , V _1, V _{2, and} V ₃ , and the scan line combiner 240 Generate adaptive scan line data.

Reflected signals received via transducer array 10 are temporarily stored in memory (FIFO) 30 via analog-to-digital converter (A / D) 20 and each memory to which a respective delay profile is applied. (FIFO ₀ , FIFO ₁ , FIFO ₂ , FIFO ₃ ) 200 are temporarily stored. The digital signal temporarily stored in the memory 200 is subjected to an individual delay profile by the delay controller 210 to receive and concentrate the preliminary scan line data.

Preliminary scan line data is generated in proportion to the number of delay controllers 210 that perform the reception focus in parallel, and the scan line data is generated by combining them. However, the number of delay profiles used is closely related to the complexity, speed, etc. of hardware and software, and should be determined in consideration of these factors in determining the number of applied delay profiles.

In one embodiment of the invention shown in FIG. 2, four delay profiles are used in parallel. Indeed, in another embodiment of the present invention, other numbers of delay profiles may be used.

The four preliminary scan line data received and focused by the four delay controllers 210 are multiplexed in the multiplexer 220 and then temporarily stored in the memory (FIFO) 230. The structure of the preliminary scan line data that is focused in parallel and shared in the memory (FIFO) 230 is shown in FIG. 3. In (D _i ), the subscript (i) means that the delay profile (i) is used, and since it is focused in parallel, all of the focused data generated by the four delay profiles can be obtained at a specific time. The scan line synthesizing unit 240 generates adaptive scan line data by combining the scan line data focused in parallel. The process of generating the adaptive scan line data by the scan line combiner 240 will be described in detail later.

In the case of the method shown in Fig. 2, since the beamformer focuses the preliminary scan line data in parallel, the frame rate of this embodiment is the same as the case of using one delay profile. However, since the number of receive channels is required by the number of uses of the delay profile, the hardware becomes complicated. However, due to the recent development of integrated circuit technology, it is possible to implement a single application specific integrated circuit (ASIC).

4 illustrates an embodiment of an ultrasound imaging system that sequentially performs beam focusing using a plurality of delay profiles according to the present invention. Compared with the embodiment of FIG. 2, it can be seen that preliminary scanning line data is focused using a single channel. In the above embodiment, the delay profile is sequentially applied to generate preliminary scan line data for each delay profile, and the scan line combiner 430 combines all preliminary scan line data to generate adaptive scan line data.

The function of the transducer array 10, analog-to-digital converter 20, and memory (FIFO) 30 is the same as that of the components shown in the embodiment of FIG. The digital signal stored temporarily in the memory 30 is read, and the delay controller 400 performs focusing by applying a first delay profile. The received focused line data is stored in a temporary storage memory (FIFO) 420. The same digital signal is read from the memory (FIFO) 30 again, and a second delay profile is applied to receive and concentrate the scan line data. The received focused scan line data is stored in the memory (FIFO) 420 again. If the same process is repeated until all delay profiles are applied, sequentially concentrating scanning line data is stored in the memory (FIFO) 420.

FIG. 5 illustrates a structure of the reception focused data that is sequentially focused and temporarily stored in the memory (FIFO) 510 when four delay profiles are used. Compared with FIG. 3, which shows the structure of data focused in parallel, it can be seen that it takes four times as long to generate four preliminary scan line data to which four delay profiles are applied.

In the process of applying the delay profile, the delay profile storage device 410 provides a delay profile to the delay controller 400. The delay profile storage device 410 includes information on all delay profiles, and provides a corresponding delay profile when requested by the delay controller 400.

The scan line combiner 430 sequentially combines the preliminary scan line data stored in the memory (FIFO) 420 to generate adaptive scan line data. The adaptive scan line data is combined by the same method as the embodiment of FIG. 2, and a detailed method will be described later.

Unlike the embodiment of FIG. 2, in the embodiment of FIG. 4, the beamformer uses a single channel. Thus, the complexity of the hardware is reduced, but the generation time of the scan line data becomes long in proportion to the number of delay profiles used. As a result, the frame rate of the ultrasound imaging system is reduced in proportion to the number of delay profiles used.

2 and 4, the scan line combiner 230 and 430 generate adaptive scan line data using a plurality of scan line data. To this end, the adaptive scanning line data synthesis method should reflect the characteristics of the medium. In the case of a still image, the method of synthesizing the scanning line data determined during the entire scanning of the ultrasonic image may be repeatedly applied to a plurality of images. On the other hand, in the case of a moving picture, a different synthesis method should be used every time the ultrasound image is scanned.

In order to determine the delay profile according to the medium, it is necessary to determine the accuracy of the focusing of the scanning line data. The determination of the reception focusing accuracy is performed for each area (hereinafter referred to as "determination area") containing predetermined preliminary scanning line data. That is, the determination region is set by dividing the ultrasound image screen, and the most accurate preliminary scan line data is determined for each determination region. 6 to 10, the adaptive scan line data generation method performed by the scan line combiner 240 and 430 will be described in detail.

6 illustrates the structures of the scan line combining units 240 and 430 in the embodiment of FIGS. 2 and 4. The scan line combiners 240 and 430 generate adaptive scan line data using the plurality of preliminary focused scan line data (data focused and received in parallel in FIG. 2 and data sequentially focused in FIG. 4). In order to generate adaptive scan line data by using the plurality of scan line data generated by the individual delay profiles, the scan line combiner 240 and 430 compares the plurality of scan line data, and selects a portion where reception focus is precisely performed. It combines the selected parts into one scanline data.

To this end, the reception focusing accuracy determining unit 600 determines the accuracy of the reception focusing. As described above, the determination of the accuracy of the reception focus is actually performed for each judgment area. In the selection of the judgment area, when setting the judgment area extensively, the calculation and system for forming the adaptive scan line are simplified, but it will be difficult to expect the formation of accurate adaptive focused data. If the judgment area is set narrow, the opposite will occur. Thus, a compromise must be found between the formation of an accurate adaptive scan line and the simplification of the system.

If the reception focus is not correct, the area divider 610 divides the required area. The accuracy judging unit 600 and the area dividing unit 610 exchange the information on the accuracy and the information on the segmentation until the accuracy of the reception focus meets a predetermined criterion due to the division of the region. The scan line combiner 620 generates adaptive scan line data using information on the accuracy of the focusing of the scan line data provided from the accuracy determiner 600 and the area division provided from the area divider 610. Each of these will be described in detail as follows.

First, a method of determining the accuracy of the reception focusing in the reception focusing accuracy determining unit 600 will be described. If focusing is done correctly, the ultrasound image will be clearly displayed. Therefore, the brightness component and the high frequency component of the screen may be used as a criterion for determining the accuracy of the reception focus. The detection of the brightness component and the high frequency component of the pixel is performed over a determination region consisting of a predetermined number of scan lines.

When the brightness component of the screen is used as a criterion of the reception focusing accuracy, the brightness component of the pixels constituting the screen is extracted to calculate an average value of the brightness component with respect to the scan line. In other words, when the average value of the brightness components of the determination region exceeds a predetermined threshold, it is determined that the reception focus is correctly performed. The average value of the scan line brightness components is expressed by the following equation.

In Equation 1, B (x, y) represents a brightness component of a pixel at coordinates (x, y) on the screen. Coordinates (x, y) are points belonging to the determination region to be extracted of the brightness component. N represents the number of pixels distributed in the determination region.

A high frequency component constituting the screen may be used as a criterion for determining whether the reception focus is correct. When the focusing is not performed correctly, the screen is reduced in high frequency components such as blurring. Therefore, the accuracy of the reception focus can be determined by extracting the high frequency components.

7 illustrates an apparatus for determining the accuracy of reception focus by extracting a high frequency component from the reception focused scan line data. The preprocessor 700 performs a preprocessing function such as automatic gain control. The noise removing unit 710 may remove a noise component, and may use a median filter. Since noise is also a high frequency component, it is necessary to remove noise in order to extract only a high frequency component representing contrast from the scan line data. The signal from which the noise is removed through the noise remover 710 is input to the high frequency component extractor 720. The high frequency component extractor 720 performs a function of extracting a frequency of a desired band. In fact, the high frequency component extractor 720 may be configured as a band filter tuned to a desired frequency band. Only the frequency component of a specific band is input to the high frequency component calculator 730 through the high frequency component extractor 720. The high frequency component calculating unit 730 calculates a predetermined frequency value through accumulation. When the value output from the high frequency component calculating unit 730 exceeds a predetermined threshold, it is determined that the reception focus is correctly performed. The predetermined frequency average value performed by the high frequency component calculating unit 730 is expressed by the following equation.

Here, F (x, y) represents a predetermined frequency component, and S represents an area of a region for detecting the predetermined frequency component. Coordinates (x, y) belong to a region to be subjected to frequency extraction.

Now, the area divider 610 divides the determination area based on the accuracy determination of the reception focus. The scan line combiner 620 combines preliminary scan line data that maximizes the value of Equation 1 or Equation 2 in the divided portion to generate adaptive scan line data.

A hierarchical segmentation technique and an edge detection technique may be used as the region segmentation method by the region divider 610.

First, a method of using the hierarchical partitioning scheme will be described in detail with reference to FIG. 8. In the hierarchical segmentation technique, segmentation for the decision region is repeated until a predetermined criterion for accuracy of reception focus is satisfied. FIG. 8 illustrates a process of dividing a determination region twice by a hierarchical partitioning scheme. For convenience of description, it is assumed that four preliminary focused data are generated using four delay profiles.

First, the accuracy of the reception focus on the determination region 800 composed of a predetermined number of scan line data by Equation 1 or Equation 2 which determines the accuracy of the reception focus by extracting the brightness of the pixel and the specific frequency component. To judge. A plurality of preliminary scan line data are received and focused by applying four delay profiles to all scan lines belonging to the determination region 800. If the value of Equation 1 or Equation 2 exceeds a predetermined threshold for one or more delayed profiles, division of the area is not performed. In this case, the preliminary scan line data maximizing the equation (1) or (2) is determined as the adaptive scan line data. In FIG. 8, it is shown that preliminary scan line data using a delay profile assuming a propagation speed V ₀ has been selected as reception focus data for the determination region 800.

When the result of Equation 1 or Equation 2 for all the delay profiles does not exceed a predetermined threshold, the first division of the determination area 800 is performed. The determination region 800 is divided into a first portion 810 and a second portion 820 through the first division. Various division methods may be used. In the embodiment of FIG. 8, a vertical division and a horizontal division are repeated based on the midpoints of the determination region 800 in the vertical and horizontal directions. However, it should be noted that in other embodiments of the present invention, other forms of division may be performed, such as, for example, repetition of vertical or horizontal division, or division on a diagonal.

For the first part 810 and the second part 820 obtained by the first division, which is the vertical division, it is determined whether the resultant value of Equation 1 or Equation 2 for all the delay profiles exceeds the threshold. When there is a delay profile exceeding the threshold value, preliminary scan line data having the maximum value of Equation 1 or 2 is selected as the scan line data for the divided portions 810 and 820. In FIG. 8, the first portion 810 preliminary scan line data applying a delay profile assuming a transmission rate V ₀ , and the second portion 820 preliminary applying a delay profile assuming a transmission rate V ₁ . The selection of scan line data as adaptive scan line data is shown.

If there is no delay profile above the threshold, a second split is performed. Referring to the drawings, it can be seen that in the second division, the second portion 820 formed by the first division is divided again, but the first portion 810 is not divided.

For the divided parts 821 and 823 subdivided by the second division, the same process as that performed after the first division is repeated. As a result, it can be seen that the divided parts 821 and 823 subdivided by the second division are applied with delay profiles assuming transmission rates V ₁ and V ₂ , respectively.

The lower part of FIG. 8 shows another division type that can be generated by the second division. In this case, it can be seen that each of the divided portions 810 and 820 by the first division is divided again in the horizontal direction. As shown in the figure, it can be seen that the determination region 800 is divided into four parts 811, 813, 821, and 823 by the second division. In FIG. 8, preliminary scan line data obtained by applying a delay profile assuming a transmission speed V ₀ is obtained by a first division part 811, and a delay assuming transmission rate V _{1 by} a second division part 813. The preliminary scan line data obtained by applying the profile, the third divided part 821 is preliminary scan line data obtained by applying the delay profile assuming the transmission rate V ₂ , and the fourth divided part 823 denotes the transmission rate ( The preliminary scan line data obtained by applying the delay profile assuming V ₃ ) is shown.

9 illustrates an area segmentation method using edge detection. 9, the media 910, 920, 930, and 940 constituting the determination region 900 which are not known from the outside are illustrated. Assume that four delay profiles are used as in the case of FIG. 8. A method of dividing the determination region 900 using edge detection is as follows.

First, the accuracy of the reception focusing on the determination region 900 is determined by Equation 1 or Equation 2 which determines the accuracy of the reception focusing by extracting the brightness of the pixel and the specific frequency component. If the value of Equation 1 or Equation 2 for the entire determination area exceeds a predetermined threshold, no area division is performed. In this case, among the plurality of preliminary focused data generated by applying the four delay profiles, the focused data that maximizes the value of Equation 1 or Equation 2 is determined as the focused data for the entire determination region 900. .

When the value of Equation 1 or Equation 2 does not reach a predetermined threshold, the edges of the mediums are detected to perform region division. The edge detection technique uses a Gaussian filter, which is a low-pass filter whose variance determines the passband. At the corners, a change of medium occurs, and therefore, a high frequency component is distributed. Thus, the signal components remaining without passing through the low pass filter represent the edges of the medium.

By the first edge detection, the determination region 900 is divided into three parts 920, 940, and 950. As shown in the figure, it can be seen that, among the internal media, the media 910 and the media 930 have no boundary detected by edge detection. Equation (1) or (2) is applied to each part divided by the primary edge detection, and the result value is compared again if it exceeds a predetermined threshold. Of the delay profiles exceeding the threshold value, the maximum value of Equation 1 or 2 is determined as the delay profile for the divided region. As shown in the figure, the divided regions 920, 940, and 950 use preliminary scan line data to which a delay profile assuming propagation speeds V _1, V ₂ , and V ₃ is applied in sequence.

If the result of Equation 1 and Equation 2 for the area divided by the first edge detection does not exceed a predetermined threshold, edge detection is repeated for each divided area. In this case, the band of the median filter may be adjusted to detect the accurate edge change.

The division of the determination region by the hierarchical division technique or the edge detection technique is repeated until the value of Equation 1 or Equation 2 for the divided region exceeds a threshold. However, in another embodiment of the present invention, the number of divisions can be limited constantly. In the final step of the division, the preliminary scanning line data to which the delay profile that maximizes the result value is applied to the division portion without determining whether the result value of Equation 1 or Equation 2 exceeds the threshold.

10 is a flowchart illustrating a process of generating adaptive scan line data by forming scan line data to which a plurality of delay profiles are applied.

First, in the reception focusing step 1000, a plurality of preliminary scan line data is generated by applying a plurality of delay profiles. In the reception focusing accuracy determination step 1010, Equation 1 or Equation 2 is calculated for each determination region for a plurality of preliminary scan line data generated by applying a plurality of delay profiles, and the result is compared with a predetermined threshold. To determine the accuracy of the reception focus. If the reception focus is correct, the process shifts to the adaptive scan line data generation step 1030, whereby the preliminary scan line data according to the delay profile maximizing the value of Equation 1 or Equation 2 for each partition is adaptive. Generate scan line data.

In the embodiment of the present invention described with reference to FIGS. 2 to 10, since the characteristics of the non-uniform medium are not known, after generating preliminary scan line data for each of the four delay profiles, the region is divided and then the optimal scan line By synthesizing the data, the characteristics of the medium can be reflected.

In another embodiment of the present invention, when the characteristics of the medium can be roughly understood, more accurate delay profiles can be generated using information on the propagation speed and refractive index of the ultrasonic wave in each medium. For example, when diagnosing a human abdomen, the medium is formed in adipose tissue, muscle tissue in order, and when diagnosing the carotid artery, the medium in the transverse direction is composed of blood. The method of generating the delay profile reflecting the characteristics of the medium will be described in detail as follows.

For convenience of explanation, it is assumed that the diagnosis site by the ultrasound imaging system is largely composed of three media. Although the medium is composed of three parts, the thickness and refractive index of the medium through which the ultrasound is actually propagated may be different depending on the characteristics of the subject and the diagnosis method of the diagnosis person.

Therefore, the delay profile input to the system shown in FIG. 2 is generated by the following method. First, the propagation speeds that can reflect the characteristics of the first medium are V _{1a to} V _1d , and the propagation rates V _{2a to} V _2d that can reflect the characteristics of the second medium, respectively, which can reflect the characteristics of the third medium. Propagation speeds V _{3a to} V _3d are estimated. The delay profile D _i is determined as a delay profile in the case of propagation speeds V _1i , V _2i and V _3i (i is any one of a to d ₎ in each medium. Subsequently, the process of dividing and synthesizing the region of the preliminary scan line data is the same as the embodiment described with reference to FIGS. 2 to 9.

In another embodiment of the present invention, a delay profile reflecting the characteristics of the medium may be generated by a method different from the above-described method. For example, if it is known in advance that the medium is determined in the form of a drawing showing the characteristics of the edge as a result of the edge detection in Figure 9, the medium experienced during the ultrasound is V ₃ , V ₁ → V ₃ , V ₁ → V ₃ → V ₂ , V ₃ → V ₂ has four forms. Therefore, the delay profile D _i that is input to the ultrasonic imaging system shown in Figure 2 a delay profile is assumed to V ₃ D _1, V _1, the delay profile is assumed to V ₃ D _2, V _1, V _3, the V ₂ The delay profile D ₃ is assumed, and the delay profile D ₄ is assumed based on V _{3 and} V ₂ .

In another embodiment of the present invention, region division may be performed before using the adaptive delay profile. In this case, one delay profile is applied to form an ultrasound image, and then the region of the medium is divided. The area segmentation of the medium may be an edge detection method or an artificial intelligence segmentation method. Thereafter, the adaptive delay profile is generated by the delay profile generation method reflecting the characteristics of the medium described above.

<Transmission focus>

Unlike adaptive reception focusing, in adaptive transmission focusing, the focusing point of a group of ultrasonic pulses once leaving the transducer array cannot be changed. In order to reflect the characteristics of the medium in the transmission focusing, considering that the propagation speed of the ultrasonic wave changes according to the change of the medium, a plurality of delay profiles associated with the propagation speeds are generated and applied, or a plurality of scan lines are applied to one scan line. You should use a method of focusing on points. Therefore, in order to reflect the characteristics of the medium, the transmission convergence is repeated (multiplexing on a kind of time axis), or a plurality of waveforms focused on different locations or multiple waveforms to which a plurality of delay profiles are applied are transmitted into one waveform at a time. Should be used.

First, a description will be given of a method of focusing transmission several times. Since this method repeats the conventional transmission focusing method several times while changing the delay profile used for transmission focusing, the transmission focusing apparatus shown in Fig. 1A can be used as it is.

In this case, some propagation speeds in the medium forming the object are determined, and a delay profile to be applied to the delay circuit 1 of FIG. 1A is determined based on the predetermined propagation speeds. That is, since the configuration of the medium constituting the target object may not be accurately specified, it is assumed that some propagation speeds are assumed, and a delay profile to be applied to the delay circuit 1 of the transmission focusing apparatus is generated based on this. In this way, a predetermined propagation speed is predetermined and the reflection signal is sequentially received from a group of pulses transmitted and focused sequentially, and the preliminary scan line data corresponding to each propagation speed is received and focused. The preliminary scanline data may be generated using the conventional reception focusing apparatus shown in FIG. 1B as it is, and a delay profile appropriate to each of the predetermined propagation speeds is applied to the delay controller 40 of FIG. 1B.

As described above, after generating a plurality of preliminary scan line data for each of the predetermined propagation speeds, they are appropriately divided and combined to implement one scan line data for the object. In the division and combination thereof, the adaptive reception focusing method described with reference to FIGS. 6 to 9 can be used.

Assuming such propagation speeds and using a method of focusing multiple times, there is an advantage that the conventional transmission focusing system and the reception focusing system can be used as they are. However, this has the disadvantage of lowering the frame rate in proportion to the propagation speed of the predetermined number of transmission focuses. For example, when three propagation speeds are planned in the medium, the frame rate of the ultrasound image is reduced to 1/3.

In order to solve the problem of deterioration of the frame, it is possible to think of a method of focusing once according to the direction of transmission focusing by using statistical data on the propagation speed in the medium. A predetermined propagation speed is estimated and a delay profile is generated according to the transmission focusing direction based on this. As statistical data on the propagation speed, the propagation speed of the medium determined by the adaptive reception focus shown in FIG. 2 or 4 may be used. In this case, it is assumed that the propagation speed of the pulse transmitted from the transducer array 10 is equal to the propagation speed of the pulse reflected and returned to the transducer array 10. In addition, in the case of diagnosing a human body, a statistical data on a propagation speed may be databased in advance for each diagnosis region, and then a method of focusing transmission may be used.

FIG. 11 illustrates an embodiment of an adaptive transmission focusing apparatus capable of applying a plurality of delay profiles during transmission focusing while not causing a problem of lowering a frame rate.

Referring to FIG. 11, ultrasonic pulses transmitted through components of one transmitter transducer array are combined by a combiner 7 across a plurality of delay circuits 1a to 1c and a plurality of waveform tables 3a to 3c. The signals are combined and then generated via an amplifier (5). Compared with FIG. 1A, which is a conventional transmission focusing apparatus, there is a difference in that a plurality of delay circuits 1 and waveform tables 3 are arranged to generate one transmission pulse. Although three delay circuits 1a to 1c and waveform tables 3a to 3c are connected to one transmitter converter array, the number of delay circuits 1 and waveform tables 13 is required. As many as possible.

FIG. 11 illustrates an embodiment in which a propagation speed of an ultrasonic pulse is changed from V1 to V3 according to a direction of transmission focus in an object to be imaged. Each of the three delay circuits and the three waveform tables are tailored to three transmission rates V1 to V3. The waveform is read from the waveform table 3 according to the output signal of each of the delay circuits, and a pulse corresponding to each of the delay profiles applied to the delay circuit is generated. Since different propagation speeds are reflected, the delay profiles applied to each of the plurality of delay circuits 1a to 1c have different delay values except for special cases.

Three waveforms to which different delay profiles are applied are combined through a combiner 7 into one signal and then transmitted through one transmitter transducer array. Therefore, the waveforms are stored in the waveform tables 3a to 3c in such a manner that the waveforms to which the respective delay profiles are applied can be separated from the reflected signals.

For this purpose, a frequency division method may be used. In this case, a waveform using the carrier frequencies f1 to f3 is stored in each of the waveform tables 3a to 3c, and a single frequency division multiplexed signal is generated by the combiner 7. Therefore, it is possible to separate the reflected signal into a signal corresponding to each of the delay profiles applied at the time of focusing through the band pass filter through which the carrier frequencies f1 to f3 are passed.

In addition, a code division method can be used. In this case, each waveform table 3a to 3c stores a waveform encoded by a code that can be separated upon reception (e.g., a Golay code having a characteristic of an orthogonal code), and then the combiner (7). By multiplexing and transmitting the signal, it is possible to separate the signals to which the respective delay profiles are applied by passing the reflected signal through a filter matched to each code. It will be apparent to those skilled in the art that various multiplexing methods capable of separating reflected signals in addition to the frequency division and code division methods can be used.

FIG. 12 illustrates a structure of a receiver capable of separating signals to which respective delay profiles are applied from a received signal when using the transmission focusing method of FIG. 11. Referring to FIG. 12, the signals received through the receiver of the transformer array 10 are focused through the conventional reception concentrator 1210 and then delayed by the three filters 1230a to 1230c of FIG. 11. Separated by profile characteristics. In the case of multiplexing by frequency division during transmission convergence, the three filters 1230a to 1230c will be bandpass filters whose center frequency is matched to the carrier frequency of the waveform data stored in the waveform table 3, and using code division during transmission convergence. In this case, it will be a filter matched to the corresponding sign of the waveform data stored in the waveform table 3.

As described above, using the transmission focusing and reception focusing methods illustrated in FIGS. 11 and 12, a plurality of preliminary scanline data are generated, and the divider and combiner 1240 divides and combines the plurality of preliminary scanline data. Generate one scan line data. The division and combiner 1240 may use the division and combination method described with reference to FIGS. 6 to 9 with respect to the adaptive reception focusing method.

FIG. 13 illustrates a structure of another receiver capable of separating the received signal for each delay profile applied at the time of focusing from the received signal when using the focusing of FIG. 11. Compared with the receiver shown in Fig. 12, the filter 1230 separating the received signal is the same except that the structure is connected between the transducer array 10 and the beamformer to separate the reflected signal prior to focusing. Do. In this case, since the reflected signal is separated according to the delay profile applied at the time of focusing prior to the focusing, the signal can be accurately separated from the receiver of FIG. 12. However, since filtering must be performed for each transducer array, the structure of the transmitter has a disadvantage in that it is more complicated than that of FIG. 12.

Thereafter, the splitter and combiner 1240 combines them from the plurality of preliminary scanline data generated by applying the adaptive transmission delay profile to form a single ultrasound image. This method is the same as in the case of FIG.

In the transmission focusing method described with reference to FIGS. 11 to 13, a method of applying a plurality of delay profiles generated based on the propagation speed for each medium has been described. However, this method transmits several times at different positions with respect to one scan line. The same can be applied to the focusing method. That is, each of the delay circuits 1 of FIG. 11 applies an optimized delay profile to each of a plurality of focal points, and each of the waveform tables 3 has received signals when the waveforms having different focal points are combined and transmitted. Save the waveform in a form that can be separated by focal point. The filters 1230 of FIGS. 12 and 13 are tailored to separate each of them from the received ultrasonic signal.

In this case, the transmission focus point may be determined for each determination region divided by the adaptive reception focus of FIG. 2 or 4. For example, in FIG. 8, the determination area 800 is divided into four parts 811, 813, 821, and 823, so that the center of each of the divided parts is focused. That is, for the divided part 811, the transmission focus is focused on the center of the divided part based on the propagation speed V0, and for the divided part 813, the transmission focus is focused on the center of the divided part based on the propagation speed V1. For the divided portion 821, transmission is focused at the center of the divided portion based on the propagation speed V2, and for the divided portion 823, the transmission is focused at the center of the divided portion based on the propagation speed V3. As a result, two delay profiles are applied to one scan line to focus the transmission.

When the present transmission focusing method is applied to the divided parts 920, 940, and 950 shown in FIG. 9, since the divided part 950 is divided by the divided part 920, the divided part 950 It is possible to use a method of focusing the transmission by focusing on each of the upper and lower portions. In this case, for the transmission focus, the division portion 950 where the area is separated by the division portion 920 is focused on the center of the upper and lower portions based on the propagation speed V2, and the division portion 920 The transmission focus is focused on the center of the split based on the propagation speed V1, and the split part 940 focuses on the center of the split based on the propagation speed V3.

<Application to Multi-beam System>

The transmission focusing and reception focusing methods using the adaptive delay profile described above can be applied to a multi-beam system. Since the multi-beam system is a reception focusing method for forming a plurality of scan lines with one transmission focusing, the transmission focusing method using the adaptive delay profile shown in FIG. 11 can be applied to a transmission focusing apparatus for forming a multi-beam as it is. have. In the case of using the transmission focus of FIG. 11, the structures of the receivers of FIGS. 12 and 13 may also be directly applied to each channel generating multiple beams.

The reception focusing method using the adaptive delay profile shown in FIGS. 2 and 4 may also be directly applied to each channel generating a plurality of scan lines in the multi-beam system.

<Adaptive send and receive convergence>

As mentioned above, although each of the transmission focusing method and the reception focusing method using the adaptive delay profile was described, it is also possible to apply these simultaneously.

In this case, the transmission focusing uses the adaptive transmission focusing method shown in FIG. 11 as it is, and in the reception focusing, the beam formers of FIG. 2 or 4 are used for the beam formers 1210 of FIGS. 12 and 13. . In this case, when using adaptive focusing and focusing at the same time, for example, focusing using 3 delay profiles and receiving focus using 4 delay profiles, 12 spares per scan line Scanline data is generated. In this case, one of the twelve preliminary scanline data must be appropriately divided and combined to generate one scanline data. The method shown in FIGS. 6 to 9 can be used.

The embodiments described so far in the present specification are intended to clarify the technical contents of the present invention to the last, and the scope of the present invention should not be construed in consultation with only such examples. It includes various modifications and changes within the spirit and claims that follow.

By using the transmission concentrating and receiving concentrating apparatus using the adaptive delay according to the present invention, it is possible to reduce the inaccuracy of the delay profile caused by the change of the medium and the error of the transmission concentrating and receiving condensation caused by this. By using the delay profile reflecting the characteristics of the medium, accurate transmission focusing and receiving focusing are possible, so that a clear ultrasound image can be realized.

Claims (39)

In the method for receiving and focusing the scanning line data in the ultrasound imaging system, a. Transmitting and concentrating an ultrasound signal to a target area in which a plurality of transducers form an ultrasound image; b. Forming a plurality of preliminary scan line data by focusing ultrasonic signals reflected from the target region and received by the plurality of transducers according to a plurality of delay profiles; c. Combining the plurality of preliminary scan line data to form scan line data Receiving concentration method comprising a. The method of claim 1, wherein c. The step of combining, d. Dividing a target area to form the ultrasound image into a plurality of determination areas; e. D. Selecting one preliminary scan line data among the plurality of preliminary scan line data for each determination region divided in the step; f. Synthesizing the selected scan line data to generate adaptive scan line data Receiving concentration method comprising a. The method of claim 2, wherein d. Split stage d1) dividing the target area into two or more determination areas; d2) using the plurality of preliminary scan line data focused in step b to determine the accuracy of the focused focus on the determination area; d3) repeating the step of further dividing the determination region until the accuracy satisfies a predetermined criterion and determining the accuracy of the reception focus for the further divided determination region; Receiving concentration method comprising a. The method of claim 1, B. The method may further include generating preliminary scan line data simultaneously by applying a plurality of delay profiles in parallel. The method of claim 1, B. The method may further include sequentially generating preliminary scan line scan line data by sequentially applying a plurality of delay profiles. The method of claim 3, The determining of the accuracy of the reception focusing in the d2 and d3 step, comprising the step of comparing the brightness average value of the pixel with a predetermined threshold value. The method of claim 3, The determining of the accuracy of the focusing in the d2 and d3 step, comprising the step of comparing the average value of the high frequency component with a predetermined threshold value. The method of claim 3, Receiving concentration method of dividing the determination region in the step d1 and d3 by the hierarchical method. The method of claim 8, And the division by the hierarchical method alternately repeats the vertical division and the horizontal division of the determination region. The method of claim 2, D. And the division of the determination area in the step is divided by the edge detection method. The method of claim 1, And the plurality of delay profiles are generated based on a combination of ultrasonic propagation speeds reflecting characteristics of a medium. The method of claim 1, Generating scan line data by one delay profile before step b, and dividing an area of the scan line data; The generation of the plurality of delay profiles in step b is generated based on the combination of the ultrasonic wave propagation speed reflecting the characteristics of the divided region. An apparatus for receiving and converging scan line data in an ultrasound imaging system for transmitting an ultrasound signal to a target region to form an ultrasound image through a plurality of transducers to form an image, a. Means for focusing the ultrasonic signals reflected from the target area and received by the transducer according to a plurality of delay profiles to form a plurality of preliminary scan line data; b. Means for combining the plurality of preliminary scan line data to form scan line data Reception focusing device comprising a. The method of claim 13, wherein b. Means to combine, c. Means for dividing a target area for forming the ultrasound image into a plurality of determination areas; d. Means for selecting one preliminary scan line data among the plurality of preliminary scan line data for each determination region divided by the dividing means; e. Means for synthesizing the selected scan line data to generate adaptive scan line data Reception focusing device comprising a. 15. The method of claim 14, wherein c. Split means c1) means for dividing the target area into two or more judgment areas; c2) means for determining the accuracy of the focusing of the determination area using the plurality of preliminary scan line data; c3) means for further dividing the judgment area until the accuracy satisfies a predetermined criterion and repeating the procedure for determining the accuracy of the reception focus for the divided judgment area; Reception focusing device comprising a. The method of claim 13, And the means for generating the preliminary scanning line data includes delay control means for simultaneously generating a plurality of reception access data by applying the plurality of delay profiles in parallel. The method of claim 13, And the means for generating the preliminary scanning line data includes delay control means for sequentially generating the plurality of reception focused data by sequentially applying the plurality of delay profiles. The method of claim 15, Means for determining the accuracy of the focusing, And a means for comparing an average value of a brightness component of a pixel belonging to each of the determination regions with a predetermined threshold value. The method of claim 15, Means for determining the accuracy of the focusing, And a means for comparing an average value of the high frequency components belonging to each of the determination regions with a predetermined threshold value. The method of claim 15, The dividing means, A reception concentrating device for dividing the determination region using a hierarchical division technique. The method of claim 15, The dividing means, A reception concentrating device for dividing the determination region using edge detection. In the focusing device of the ultrasonic imaging system, Transmitting and concentrating a group of ultrasonic pulses by applying a plurality of delay profiles; Transmitting the focused ultrasound pulse group Transmission focusing method comprising a. The transmission focusing method of claim 22, wherein the plurality of delay profiles are based on a propagation speed in a target area to form an ultrasound image. 23. The method of claim 22, wherein the plurality of delay profiles are based on delay values focused on a plurality of locations with respect to one scan line. The method according to any one of claims 22 to 24, The focusing step is a step of sequentially focusing a group of ultrasonic pulses by sequentially applying the plurality of delay profiles, and the step of transmitting is a step of sequentially transmitting the group of ultrasound pulses focused on sequentially Focusing method. The method according to any one of claims 22 to 24, And the step of focusing includes applying a delay profile generated based on the determined propagation speed while predetermining a propagation speed in the target area that changes according to the transmission focusing direction. The method according to any one of claims 22 to 24, Transmitting and focusing the group of ultrasonic pulses, in order to generate each ultrasonic pulse belonging to the group of ultrasonic pulses, Applying each of the plurality of delay profiles; Generating a plurality of waveforms from waveform data corresponding to each of the plurality of delay profiles; Multiplexing the generated plurality of waveforms Receiving concentration method comprising a. In ultrasound imaging system, Means for focusing a group of ultrasonic pulses by applying a plurality of delay profiles; Means for transmitting the focused group of ultrasonic pulses Transmission focusing device comprising a. 29. The transmission focusing apparatus of claim 28, wherein the plurality of delay profiles are based on a propagation speed in a target area to form an ultrasound image. 29. The apparatus of claim 28, wherein the plurality of delay profiles are based on delay values focused on a plurality of locations with respect to one scan line. The method according to any one of claims 28 to 30, Means for focusing the group of ultrasonic pulses, to generate each of the ultrasonic pulses belonging to the group of ultrasonic pulses, Means for applying each of the plurality of delay profiles; Means for generating a plurality of waveforms from waveform data corresponding to each of the plurality of delay profiles; Means for multiplexing the generated plurality of waveforms Reception focusing device comprising a. In ultrasonic imaging system, Transmitting means for focusing a group of ultrasonic pulses by applying a plurality of delay profiles; Receiving means for focusing the reflected signals from the target area based on a plurality of delay profiles applied at the time of focusing; Ultrasound imaging system comprising a. The ultrasound imaging system of claim 32, wherein the plurality of delay profiles are based on a propagation speed in a target area to form an ultrasound image. The ultrasound imaging system of claim 32, wherein the plurality of delay profiles are based on delay values focused on a plurality of positions with respect to one scan line. The method of any one of claims 32 to 34, wherein The transmitting means, to form each of the ultrasonic pulses belonging to the group of ultrasonic pulses, Means for applying each of the plurality of delay profiles; Means for generating a plurality of waveforms from waveform data corresponding to each of the plurality of delay profiles; Means for multiplexing the generated plurality of waveforms Ultrasound imaging system comprising a. The method of any one of claims 32 to 34, wherein The receiving means, Means for receiving and focusing the reflected signal from the target region to generate scan line data; Means for separating the scan line data into a plurality of preliminary scan line data corresponding to each of a plurality of delay profiles applied at the time of transmission focusing. Ultrasound imaging system comprising a. The method of any one of claims 32 to 34, wherein The receiving means, A transducer array for receiving the reflected signals from the group of ultrasonic pulses; Means for separating the reflected signals received by each of the transducer arrays into a plurality of signals corresponding to each of the plurality of delay profiles applied at the time of focusing; Reception focusing means for focusing each of the separated signals to generate preliminary scan line data corresponding to each of the plurality of delay profiles applied during transmission focusing; Ultrasound imaging system comprising a. The method of claim 36, wherein the receiving means, Synthesis means for dividing a target region to form an ultrasound image into a determination region, selecting one of the plurality of preliminary scan line data for all the divided determination regions, and synthesizing the selected preliminary scan line data to generate one scan line data Ultrasonic imaging system further comprising. The method of claim 37, wherein the receiving means, Synthesis means for dividing a target region to form an ultrasound image into a determination region, selecting one of the plurality of preliminary scan line data for all the divided determination regions, and synthesizing the selected preliminary scan line data to generate one scan line data Ultrasonic imaging system further comprising.