WO2017122414A1

WO2017122414A1 - Ultrasonic diagnostic device and sonic speed quantification method

Info

Publication number: WO2017122414A1
Application number: PCT/JP2016/082043
Authority: WO
Inventors: 拓明山本
Original assignee: 富士フイルム株式会社
Priority date: 2016-01-13
Filing date: 2016-10-28
Publication date: 2017-07-20

Abstract

This ultrasonic diagnostic device comprises: a region-of-interest setting unit (17) that sets a region of interest (R2) on an ultrasonic image; a time difference measurement data acquisition unit (21) that compares a plurality of pieces of element data which are output from a plurality of elements of an array transducer, and acquires time difference measurement data indicating time differences among the pieces of element data; a time difference calculation data acquisition unit (22) that acquires time difference calculation data indicating time differences among the pieces of element data on the basis of respective distances from a reflection point to the plurality of elements and an assumed sonic speed that has been set; and an overall sonic speed determination unit (23) that determines an overall sonic speed in a region other than said region of interest on the basis of the difference between first time difference measurement data acquired in association with elements, among said plurality of elements, that have received an ultrasonic echo passing through said region other than said region of interest (R2) and first time difference calculation data acquired in association with said elements, among said plurality of elements, that have received the ultrasonic echo passing through said region other than said region of interest (R2) and by setting an overall assumed sonic speed as the assumed sonic speed.

Description

Ultrasonic diagnostic apparatus and sound speed quantification method

The present invention relates to an ultrasonic diagnostic apparatus and a sound velocity quantification method, and more particularly, to sound velocity quantification in a region between an array transducer and an ultrasonic beam reflection point.

Conventionally, in the medical field, an ultrasonic diagnostic apparatus using an ultrasonic image has been put into practical use. In general, in this type of ultrasonic diagnostic apparatus, an ultrasonic beam is transmitted from an array transducer in which a plurality of elements are arranged into the subject, and ultrasonic echoes from the subject are received by the array transducer, and element data is received. And an elemental data is electrically processed by the apparatus body to generate an ultrasonic image.

In such an ultrasonic diagnostic apparatus, when an ultrasonic beam is transmitted for the purpose of improving the azimuth resolution of the ultrasonic image, the ultrasonic beam is transmitted from each element of the array transducer by focusing on each scanning line. When the transmission focus is performed and the ultrasonic echo is received, the reception focus for aligning the time phases of the element data according to the arrangement position of each element of the array transducer is performed.
These transmission focus and reception focus are performed using the sound velocity of the propagation medium of the ultrasonic beam, but it is necessary to estimate the sound velocity in the subject that is the propagation medium.

For example, in the ultrasonic diagnostic apparatus disclosed in Patent Document 1, a plurality of received signals obtained from a plurality of elements of an array transducer are used, and a plurality of evaluation frames are formed corresponding to a plurality of sound speed candidates, A sound speed candidate that maximizes the intensity of the signal obtained by the phasing addition processing in the evaluation frame is used as an optimum sound speed estimation value.

JP2015-62483A

However, in the apparatus of Patent Document 1, phasing addition processing is performed by applying a uniform sound speed candidate to a received signal acquired by a plurality of elements of an array transducer. When the region between the reflection points has a uniform sound velocity, the optimum sound velocity value can be estimated, but the sound velocity in the region between the plurality of elements and the reflection point in the subject is uniform. Otherwise, there is a problem that the accuracy of sound speed estimation is lowered.
In particular, the speed of sound is often different in a lesion area compared to other regions, and if a lesion area exists between multiple elements of an array transducer and a reflection point in a subject, the sound speed is accurately estimated. Will become difficult.

The present invention has been made to solve such a conventional problem. Even when the sound speed in the region between the plurality of elements of the array transducer and the reflection point is not uniform, the sound speed can be accurately obtained. An object of the present invention is to provide an ultrasonic diagnostic apparatus and a sound speed quantification method that can be quantified.

The ultrasonic diagnostic apparatus according to the present invention transmits an ultrasonic beam toward an object from an array transducer in which a plurality of elements are arranged, receives an ultrasonic echo from the object, and generates an ultrasonic image A diagnostic apparatus, a region-of-interest setting unit for setting a region of interest on an ultrasound image, and an ultrasonic wave reflected by the reflection point in response to transmission of an ultrasonic beam toward the reflection point in the subject A time difference measurement data acquisition unit that compares a plurality of element data output from a plurality of elements that have received an echo to acquire a time difference measurement data that represents a time difference between the element data, and a distance from the reflection point to each of the plurality of elements A time difference calculation data acquisition unit for acquiring time difference calculation data representing a time difference between element data based on the set assumed sound speed, and an overall assumed sound speed as an assumed sound speed, and a plurality of elements The first time difference measurement data acquired by the time difference measurement data acquisition unit corresponding to the element that has received the ultrasonic echo that passes through the region other than the region of interest, the overall assumed sound speed is set as the assumed sound speed, and the plurality of elements The total sound speed corresponding to the region other than the region of interest based on the difference from the first time difference calculation data acquired by the time difference calculation data acquisition unit corresponding to the element that has received the ultrasonic echo passing through the region other than the region of interest. And an overall sound speed determination unit.

The overall sound speed determination unit calculates a difference between the first time difference measurement data and the first time difference calculation data acquired corresponding to an element that has received an ultrasonic echo passing through a region other than the region of interest among a plurality of elements. An overall assumed sound speed at which the determination value calculated based on the first threshold value is equal to or less than the first threshold value can be determined as the overall sound speed.
Furthermore, the overall sound speed determination unit uses the sum of absolute values of the differences between the first time difference measurement data corresponding to the plurality of elements and the first time difference calculation data or the sum of squares of the absolute values of the differences as a determination value. Can do.
The second time difference measurement data acquired by the time difference measurement data acquisition unit corresponding to the element that has received the ultrasonic echo that passes through the region of interest, the local assumed sound speed as the assumed sound speed, and the ultrasonic echo that passes through the region of interest It is preferable to include a local sound speed determination unit that determines the local sound speed in the region of interest based on the difference from the second time difference calculation data acquired by the time difference calculation data acquisition unit corresponding to the received element.

The total sound speed determination unit is configured to display a region of interest set by the region of interest setting unit when the region of interest set by the region of interest setting unit has at least one of a length in the scanning direction and a length in the depth direction equal to or less than a set value. Only when the length in the scanning direction and the length in the depth direction are both larger than the set value and the straight line passing through the region of interest is less than or equal to a predetermined ratio among the plurality of straight lines connecting the reflection point and the plurality of elements. Can be configured to determine.
In this case, the local sound speed determination unit may determine the local sound speed only when the length in the scanning direction and the length in the depth direction of the region of interest set by the region of interest setting unit are both larger than the set value.
The time difference measurement data acquisition unit can acquire time difference measurement data representing a time difference between adjacent elements, and the time difference calculation data acquisition unit can be configured to acquire time difference calculation data representing a time difference between adjacent elements. . Alternatively, the time difference measurement data acquisition unit acquires time difference measurement data representing a time difference between the reference element and other elements among the plurality of elements, and the time difference calculation data acquisition unit acquires the difference between the reference element and other elements. You may comprise so that the time difference calculation data showing the time difference between elements may be acquired.

The time difference measurement data acquisition unit acquires time difference measurement data for each of the plurality of reflection points by transmitting an ultrasonic beam toward the plurality of reflection points located on different scanning lines, and the time difference calculation data acquisition unit The time difference calculation data is acquired for each of the plurality of reflection points, and the overall sound speed determination unit corresponds to the element that has received the ultrasonic echo that passes through the region other than the region of interest among the plurality of elements and corresponds to the plurality of reflection points. Based on a plurality of first time difference calculation data and a plurality of first time difference calculation data for a plurality of reflection points corresponding to an element that has received an ultrasonic echo passing through a region other than the region of interest among the plurality of elements. Can also be determined.
In this case, the overall sound speed determination unit may determine the overall assumed sound speed at which the difference between the plurality of first time difference measurement data and the plurality of first time difference calculation data for the plurality of reflection points is minimum as the overall sound speed. . Alternatively, the total sound speed determination unit calculates a plurality of global sound speed candidate values for each of the plurality of reflection points based on a difference between the first time difference measurement data and the first time difference calculation data for each of the plurality of reflection points. In addition, the overall sound speed can also be determined based on a plurality of candidate values for the overall sound speed.
The region-of-interest setting unit can set the region of interest according to user designation. Alternatively, the region-of-interest setting unit may automatically set the region of interest from the generated ultrasonic image.

The sound velocity quantification method according to the present invention sets a region of interest on an ultrasonic image and receives an ultrasonic echo reflected by the reflection point in response to transmission of an ultrasonic beam toward the reflection point in the subject. A plurality of element data output from a plurality of elements of the array transducer are compared to obtain time difference measurement data representing a time difference between the element data, and a distance from the reflection point to each of the plurality of elements and a set assumed sound speed Time difference calculation data representing the time difference between the element data is obtained, the overall assumed sound speed is set as the assumed sound speed, and the ultrasonic echo that passes through the region other than the region of interest among the plurality of elements is received. Corresponding to the acquired first time difference measurement data and the element that has set the overall assumed sound speed as the assumed sound speed and has received an ultrasonic echo that passes through a region other than the region of interest among the plurality of elements. It is a method of determining the overall speed of sound corresponding to the region other than the region of interest based on the difference between the acquired first time difference calculation data.

According to the present invention, a region of interest is set on an ultrasonic image, a plurality of element data output from a plurality of elements of an array transducer are compared, time difference measurement data representing a time difference between element data is acquired, and reflection is performed. Obtain time difference calculation data representing the time difference between element data based on the distance from the point to each of the plurality of elements and the set assumed sound speed, and set the overall assumed sound speed as the assumed sound speed. First time difference measurement data acquired corresponding to an element that has received an ultrasonic echo that passes through a region other than, and an overall assumed sound speed as an assumed sound speed, and a super-pass that passes through a region other than the region of interest among a plurality of elements Since the entire sound speed corresponding to the region other than the region of interest is determined based on the difference from the first time difference calculation data acquired corresponding to the element that has received the acoustic echo, the array It is possible to quantify accurately the sound speed even if the sound velocity is not uniform in the region between the plurality of elements of transducer and the reflection point.

1 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention. 3 is a block diagram showing an internal configuration of a receiving circuit in the first embodiment. FIG. 3 is a block diagram illustrating an internal configuration of an image generation unit according to Embodiment 1. FIG. 4 is a block diagram showing an internal configuration of a sound speed quantification unit in Embodiment 1. FIG. It is a figure which shows a mode that the ultrasonic echo from the reflective point in a subject reaches | attains the several element of an array transducer. It is a figure which shows the ultrasonic echo emitted from the reflective point in a subject and toward each element. It is a figure which shows the waveform which connects the point with the largest amplitude of the ultrasonic echo which is emitted from the reflective point in a subject and goes to each element. It is a graph which shows the time difference measurement data between adjacent elements. It is a figure which shows the geometric arrangement | positioning relationship between the element which received the ultrasonic echo which passes along areas other than the region of interest, and the reflective point in a subject. It is a graph which shows the calculated value of the time which receives the ultrasonic echo from the reflective point in a subject by each element which received the ultrasonic echo which passes along areas other than a region of interest. It is a graph which shows the time difference calculation data between the adjacent elements which received the ultrasonic echo which passes along areas other than the region of interest. It is the graph which displayed by superimposing the time difference measurement data and the time difference calculation data between the adjacent elements which received the ultrasonic echo which passes through areas other than the region of interest. It is a graph which shows the difference of the time difference measurement data and the time difference calculation data between the adjacent elements which received the ultrasonic echo which passes through areas other than the region of interest. It is a figure which shows the geometric arrangement | positioning relationship between the element which received the ultrasonic echo which passes through a region of interest, and the reflective point in a subject. It is a graph which shows the calculated value of the time which receives the ultrasonic echo from the reflective point in a subject by each element which received the ultrasonic echo which passes the region of interest. It is a graph which shows the time difference calculation data between the adjacent elements which received the ultrasonic echo which passes the region of interest. It is the graph which displayed by superimposing the time difference measurement data and time difference calculation data between the adjacent elements which received the ultrasonic echo which passes through the region of interest. It is a graph which shows the difference of the time difference measurement data and the time difference calculation data between the adjacent elements which received the ultrasonic echo which passes the region of interest. 3 is a flowchart showing an operation of the ultrasonic diagnostic apparatus according to the first embodiment. FIG. 10 is a diagram illustrating a state in which an ultrasonic echo from one reflection point in the second embodiment reaches a plurality of elements of an array transducer. It is a figure which shows a mode that the ultrasonic echo from the other reflective point in Embodiment 2 arrives at the several element of an array transducer. 6 is a flowchart showing the operation of the ultrasonic diagnostic apparatus according to the second embodiment. 6 is a graph showing the difference between time difference measurement data and time difference calculation data between adjacent elements that have received ultrasonic echoes corresponding to two reflection points and passing through a region other than the region of interest in the second embodiment. 10 is a flowchart showing the operation of the ultrasonic diagnostic apparatus according to the third embodiment. 3 is a flowchart showing an operation of a quantification process 100. 5 is a flowchart showing an operation of a quantification process 200. 10 is a flowchart showing the operation of an ultrasonic diagnostic apparatus according to a modification of the third embodiment. 5 is a flowchart showing an operation of a quantification process 300.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1
FIG. 1 shows the configuration of an ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention. The ultrasonic diagnostic apparatus includes an array transducer 1, and a transmission circuit 2 and a reception circuit 3 are connected to the array transducer 1. An image generating unit 4, a display control unit 5, and a display unit 6 are sequentially connected to the receiving circuit 3. An element data memory 7 is connected to the receiving circuit 3, a sound speed quantification unit 8 is connected to the element data memory 7 and the image generation unit 4, and a region of interest setting unit 17 is connected to the sound speed quantification unit 8.
Further, the control unit 9 is connected to the transmission circuit 2, the reception circuit 3, the image generation unit 4, the display control unit 5, the sound speed quantification unit 8, and the region of interest setting unit 17, and the operation unit 10 and the storage unit 11 are connected to the control unit 9. Are connected to each other.

The array transducer 1 has a plurality of elements (ultrasonic transducers) arranged one-dimensionally or two-dimensionally. Each of these elements transmits an ultrasonic wave according to a drive signal supplied from the transmission circuit 2 and receives an ultrasonic echo from the subject to output a reception signal. Each element is, for example, a piezoelectric ceramic represented by PZT (lead zirconate titanate), a polymer piezoelectric element represented by PVDF (polyvinylidene fluoride), or PMN-PT (magnesium niobate / lead titanate solid solution). It is comprised by the vibrator | oscillator which formed the electrode in the both ends of the piezoelectric material which consists of a piezoelectric single crystal etc. which are represented by.

When a pulsed or continuous wave voltage is applied to the electrodes of such a vibrator, the piezoelectric body expands and contracts, and pulsed or continuous wave ultrasonic waves are generated from the respective vibrators, and the synthesis of those ultrasonic waves. As a result, an ultrasonic beam is formed. In addition, each transducer generates an electric signal by expanding and contracting by receiving propagating ultrasonic waves, and these electric signals are output as ultrasonic reception signals.

The transmission circuit 2 includes, for example, a plurality of pulse generators, and ultrasonic waves transmitted from a plurality of elements of the array transducer 1 based on a transmission delay pattern selected according to a control signal from the control unit 9. Adjusts the delay amount of each drive signal so as to form an ultrasonic beam, and supplies it to a plurality of elements.
As shown in FIG. 2, the reception circuit 3 has a configuration in which an amplification unit 12 and an AD (Analogue Digital) conversion unit 13 are connected in series. The receiving circuit 3 amplifies the reception signal output from each element of the array transducer 1 by the amplifying unit 12, and digitizes the element data obtained by the AD converting unit 13. The image generating unit 4 and the element data memory 7 Output to.

As shown in FIG. 3, the image generation unit 4 has a configuration in which a signal processing unit 14, a DSC (Digital Scan Converter) 15, and an image processing unit 16 are sequentially connected in series.
Based on the reception delay pattern selected according to the control signal from the control unit 9, the signal processing unit 14 gives each element data a respective delay and adds (phased addition) according to the set sound speed. Receive focus processing. By this reception focus processing, a sound ray signal in which the focus of the ultrasonic echo is narrowed is generated. Further, the signal processing unit 14 corrects the attenuation by the distance according to the depth of the reflection position of the ultrasonic wave on the sound ray signal, and then performs envelope detection processing to thereby obtain a tomography relating to the tissue in the subject. A B mode (Brightness Mode) image signal which is image information is generated.

The DSC 15 converts (raster conversion) the B-mode image signal generated by the signal processing unit 14 into an image signal according to a normal television signal scanning method.
The image processing unit 16 performs various necessary image processing such as gradation processing on the B-mode image signal input from the DSC 15, and then outputs the B-mode image signal to the display control unit 5.

The display control unit 5 displays an ultrasound diagnostic image on the display unit 6 based on the B-mode image signal output from the image generation unit 4.
The display unit 6 includes a display device such as an LCD (Liquid Crystal Display), for example, and displays an ultrasound diagnostic image under the control of the display control unit 5.

The element data memory 7 sequentially stores element data output from the receiving circuit 3.
The sound velocity quantifying unit 8 uses the element data stored in the element data memory 7 to select a region R1 other than the region of interest R2 set by the region-of-interest setting unit 17 among the imaging regions imaged by the array transducer 1. The overall sound speed V1 indicating the sound speed and the local sound speed V2 indicating the sound speed of the region of interest R2 are each quantified and output to the image generation unit 4. As shown in FIG. 4, the sound velocity quantification unit 8 includes a time difference measurement data acquisition unit 21 and a time difference calculation data acquisition unit 22, and the time difference measurement data acquisition unit 21 and the time difference calculation data acquisition unit 22 include An overall sound speed determination unit 23 and a local sound speed determination unit 25 are connected to each other. The region-of-interest setting unit 17 is connected to the time difference calculation data acquisition unit 22, the overall sound speed determination unit 23, and the local sound speed determination unit 25.

The region-of-interest setting unit 17 sets the region of interest R2 within the imaging region imaged by the array transducer 1. The region of interest R2 is set in accordance with, for example, the position of the lesion, and the region of interest setting unit 17 sets the region of interest R2 based on the user designation input from the operation unit 10, or the image generating unit 4 The region of interest R2 can be automatically set by recognizing the generated ultrasonic image.

The control unit 9 controls each unit of the ultrasonic diagnostic apparatus based on a command input from the operation unit 10 by the user.
The operation unit 10 is for a user to perform an input operation, and can be formed from a keyboard, a mouse, a trackball, a touch panel, or the like.
The storage unit 11 stores an operation program and the like. A hard disk, a flexible disk, an MO (Magneto-Optical Disk), an MT (Magnetic Tape), a RAM (Random Access Memory), a CD-ROM (Compact Disk Read Only Memory). Recording media such as DVD-ROM (Digital Versatile Disk Read Only Memory), SD card (Secure Digital Card), CF card (Compact Flash Card), USB memory (Universal Serial Bus Memory), or server can be used. .
The image generation unit 4, the display control unit 5, the sound speed quantification unit 8, the control unit 9, and the region of interest setting unit 17 are each a CPU (Central Processing Unit) and operations for causing the CPU to perform various processes. Although composed of programs, they may be composed of digital circuits. The image generation unit 4, the display control unit 5, the sound speed quantification unit 8, the control unit 9, and the region-of-interest setting unit 17 may be partially or wholly integrated into one CPU.

Here, the operation of the sound velocity quantification unit 8 will be described in detail.
The time difference measurement data acquisition unit 21 corresponds to the ultrasonic wave transmitted from the plurality of elements of the array transducer 1 toward the reflection point in the subject from the element data stored in the element data memory 7. By reading a plurality of element data output from a plurality of elements of the array transducer 1 that has received the ultrasonic echo reflected by the reflection point, and comparing the read plurality of element data, the element data of adjacent elements The time difference measurement data Dm representing the time difference ΔT is acquired.

For example, as shown in FIG. 5, an ultrasonic beam is transmitted from a plurality of elements E1 to En of the array transducer 1 with the reflection point A in the subject as a focal point. It is assumed that the reflected ultrasonic echo is received by a plurality of elements E1 to En. The time at which the ultrasonic echo from the reflection point A is received by each element with the point in time when the ultrasonic echo is emitted from the reflection point A as a function of the distance between the reflection point A and each element. It becomes. As shown in FIG. 6, among the plurality of elements E1 to En, the element Ec that receives the earliest ultrasonic echo at the element Ec that is the shortest from the reflection point A and is disposed at a position away from the element Ec. As the distance from the reflection point A increases, the ultrasonic echo is received later.

As shown in FIG. 5, when the lesioned part B exists on the path of the ultrasound echo and the sound speed at the lesioned part B is higher than the surrounding sound speed, the ultrasound echo that has passed through the lesioned part B is The time received by the corresponding element is advanced by the amount that has passed through the high sound velocity region. FIG. 7 shows a representative point of the ultrasonic echo where the maximum amplitude of the ultrasonic echo directed to each element shown in FIG. 6 is represented. It can be seen that the ultrasonic echoes passing through the lesion B toward the element Ek and the element Ek + 1 are ahead of the surrounding ultrasonic echoes. Here, k represents an integer in the range of 1 to n.

Therefore, the time difference measurement data Dm as shown in FIG. 8 is calculated by calculating the time difference ΔT between the element data of the adjacent elements for the element data output from the plurality of elements E1 to En that have received the ultrasonic echo. Is acquired. In FIG. 8, the horizontal axis represents adjacent elements.

On the other hand, the time difference calculation data acquisition unit 22 uses the distances from the reflection point A in the subject to the plurality of elements E1 to En of the array transducer 1 and the set assumed sound speeds to determine the elements of adjacent elements. Time difference calculation data Dc representing the calculation value of the time difference ΔT between the data is calculated and acquired.
First, when the total sound speed V1 corresponding to the region R1 other than the region of interest R2 is determined by the total sound speed determination unit 23, the time difference calculation data acquisition unit 22 inputs data indicating the region of interest R2 from the region of interest setting unit 17. At the same time, an overall assumed sound speed Va indicating the assumed sound speed of the region R1 other than the region of interest R2 is input from the overall sound speed determination unit 23, and first time difference calculation data Dc1 for the region R1 other than the region of interest R2 is acquired.

As shown in FIG. 9, when i is an integer in the range of 1 to n, and Li is the distance from the reflection point A to the element Ei that has received the ultrasonic echo passing through the region R1 other than the region of interest R2, The propagation time Ti of the ultrasonic echo from the reflection point A to the element Ei is Ti = Li / Va. Therefore, based on the geometrical arrangement of the reflection point A and the plurality of elements E1 to En and the overall assumed sound velocity Va, the point in time when an ultrasonic echo is emitted from the reflection point A is passed through the region R1 other than the region of interest R2. When the time at which the ultrasonic echo from the reflection point A is received by each element that has received the ultrasonic echo is obtained by calculation, the graph shown in FIG. 10 is obtained. In FIG. 10, Er represents one or more elements that have received an ultrasonic echo passing through the region of interest R2, and the reception time of the ultrasonic echo corresponding to this element Er is blank.

Here, as an initial value of the overall assumed sound speed Va corresponding to the region R1 other than the region of interest R2, 1530 m / s or 1540 m / s, which is a general sound speed value of a normal tissue, can be set.
Based on the graph of FIG. 10, by calculating the time difference ΔT between the element data of adjacent elements, the first time difference calculation data Dc1 as shown in FIG. 11 is obtained for the region R1 other than the region of interest R2. Is done. In FIG. 11, Fr represents an adjacent element corresponding to the element Er that has received the ultrasonic echo passing through the region of interest R2, and the time difference ΔT in the adjacent element Fr is blank.

The total sound speed determination unit 23 includes the first time difference measurement data Dm1 and the time difference calculation data acquisition unit acquired by the time difference measurement data acquisition unit 21 corresponding to the element that has received the ultrasonic echo passing through the region R1 other than the region of interest R2. The difference ΔD1 of the first time difference calculation data Dc1 acquired in Step 22 is obtained, a determination value G1 is calculated based on the difference ΔD1, and the total assumed sound speed Va at which the determination value G1 is equal to or less than the first threshold Th1 is obtained. The overall sound speed V1 corresponding to the region R1 other than the region of interest R2 is determined.

For example, when the first time difference calculation data Dc1 shown in FIG. 11 is displayed superimposed on the first time difference measurement data Dm1 corresponding to the element that has received the ultrasonic echo passing through the region R1 other than the region of interest R2, FIG. As can be seen from the graph, the first time difference calculation data Dc1 is located at a position shifted from the first time difference measurement data Dm1. This is because the total assumed sound speed Va used when obtaining the first time difference calculation data Dc1 is different from the actual sound speed, so that it is actually different from the first time difference calculation data Dc1 calculated based on the total assumed sound speed Va. This is probably because an error has occurred between the measured first time difference measurement data Dm1.

Therefore, as shown in FIG. 13, the overall sound speed determination unit 23 obtains a difference ΔD1 between the first time difference measurement data Dm1 and the first time difference calculation data Dc1, and the determination value G1 based on the difference ΔD1 is the first value. The calculation of the difference ΔD1 and the determination value G1 is repeated using the first time difference calculation data Dc1 acquired by the time difference calculation data acquisition unit 22 while changing the value of the overall assumed sound speed Va until the threshold Th1 becomes equal to or less than the threshold Th1. . As the determination value G1, the sum of absolute values of the difference ΔD1 or the sum of squares of the absolute values of the difference ΔD1 can be used.
In this way, the overall assumed sound speed Va at which the determination value G1 is equal to or less than the first threshold Th1 is determined as the overall sound speed V1.

In addition, when the local sound speed determination unit 25 determines the local sound speed V2 corresponding to the region of interest R2, the time difference calculation data acquisition unit 22 inputs data indicating the region of interest R2 from the region of interest setting unit 17 and the local sound speed. The local assumed sound speed Vb indicating the assumed sound speed of the region of interest R2 is input from the determination unit 25, and second time difference calculation data Dc2 for the region of interest R2 is acquired.

As shown in FIG. 14, j is an integer in the range of 1 to n, and from the reflection point A to the region of interest R2 on the path of the ultrasonic echo from the reflection point A to the element Ej through the region of interest R2. Lj1, the distance in the region of interest R2 is Lj2, and the distance from the region of interest R2 to the element Ej is Lj3, the overall sound speed V1 of the region R1 other than the region of interest R2 is determined by the overall sound speed determination unit 23. Therefore, the propagation time Tj of the ultrasonic echo from the reflection point A to the element Ej is Tj = (Lj1 / V1) + (Lj2 / Vb) + (Lj3 / V1).
Therefore, based on the geometrical arrangement of the reflection point A and the plurality of elements E1 to En and the local assumed sound velocity Vb, the ultrasonic echo passing through the region of interest R2 is set with the origin at the time when the ultrasonic echo is emitted from the reflection point A. When the time at which an ultrasonic echo from the reflection point A is received by each received element is obtained by calculation, the graph shown in FIG. 15 is obtained. In FIG. 15, the reception time of the ultrasonic echo corresponding to elements other than the element Er that has received the ultrasonic echo passing through the region of interest R2 is blank.

Here, as the initial value of the local assumed sound speed Vb corresponding to the region of interest R2, 1530 m / s or 1540 m / s, which is a general sound speed value of a normal tissue, can be set in the same manner as the overall assumed sound speed Va. .
By calculating the time difference ΔT between the element data of adjacent elements based on the graph of FIG. 15, second time difference calculation data Dc2 as shown in FIG. 16 is obtained for the region of interest R2. In FIG. 16, the time difference ΔT in the adjacent elements other than the adjacent element Fr corresponding to the element Er that has received the ultrasonic echo passing through the region of interest R2 is blank.

The local sound speed determination unit 25 is acquired by the second time difference measurement data Dm2 acquired by the time difference measurement data acquisition unit 21 and the time difference calculation data acquisition unit 22 corresponding to the element that has received the ultrasonic echo passing through the region of interest R2. A difference ΔD2 of the second time difference calculation data Dc2 is obtained, a determination value G2 is calculated based on the difference ΔD2, and a local assumed sound speed Vb at which the determination value G2 is equal to or less than the first threshold Th1 is set in the region of interest R2. The corresponding local sound speed V2 is determined.

For example, when the second time difference calculation data Dc2 shown in FIG. 16 is displayed superimposed on the second time difference measurement data Dm2 corresponding to the element that has received the ultrasonic echo passing through the region of interest R2, as shown in FIG. In addition, it can be seen that the second time difference calculation data Dc2 is at a position shifted from the second time difference measurement data Dm2. This is because the local assumed sound speed Vb used when obtaining the second time difference calculation data Dc2 is different from the actual sound speed, and therefore actually calculated with the second time difference calculation data Dc2 calculated based on the local assumed sound speed Vb. This is probably because an error has occurred between the measured second time difference measurement data Dm2.

Accordingly, as shown in FIG. 18, the local sound speed determination unit 25 obtains a difference ΔD2 between the second time difference measurement data Dm2 and the second time difference calculation data Dc2, and the determination value G2 based on the difference ΔD2 is the first value. The calculation of the difference ΔD2 and the determination value G2 is repeated using the second time difference calculation data Dc2 acquired by the time difference calculation data acquisition unit 22 while changing the value of the local assumed sound speed Vb until the threshold Th1 becomes equal to or less than the threshold Th1. . As the determination value G2, the sum of absolute values of the difference ΔD2 or the sum of squares of the absolute values of the difference ΔD2 can be used.
In this way, the assumed local sound speed Vb at which the determination value G2 is equal to or less than the first threshold value Th1 is determined as the local sound speed V2.

Next, the operation of the first embodiment will be described with reference to the flowchart of FIG.
First, in Step S1, the region of interest R2 is set by the region of interest setting unit 17 between the plurality of elements E1 to En of the array transducer 1 and the reflection point A in the subject.
In subsequent step S2, ultrasonic waves are transmitted / received only once from the plurality of elements E1 to En of the array transducer 1 toward the reflection point A in the subject, and in step S3, element data is acquired. That is, ultrasonic waves are transmitted from the plurality of elements E1 to En to the reflection point A according to the drive signal supplied from the transmission circuit 2, and reception signals are received from the elements E1 to En that have received the ultrasonic echoes from the reflection point A. The data is output to the receiving circuit 3, element data is generated by the receiving circuit 3, and sequentially stored in the element data memory 7.

Next, in step S4, the time difference measurement data acquisition unit 21 of the sound velocity quantification unit 8 compares a plurality of element data, and acquires time difference measurement data Dm representing the time difference ΔT between element data of adjacent elements. Is done. Furthermore, in step S5, the initial value of the overall assumed sound velocity Va corresponding to the region R1 other than the region of interest R2 is set by the overall sound velocity determination unit 23, and the first difference for the region R1 other than the region of interest R2 is set by the time difference calculation data acquisition unit 22. Time difference calculation data Dc1 is acquired.
Then, in step S6, based on the first time difference measurement data Dm1 and the first time difference calculation data Dc1 corresponding to the element that has received the ultrasonic echo passing through the region R1 other than the region of interest R2 by the overall sound speed determination unit 23. The difference ΔD1 and the determination value G1 are calculated, and the first difference acquired by the time difference calculation data acquisition unit 22 while changing the value of the overall assumed sound speed Va until the determination value G1 becomes equal to or less than the first threshold Th1. The calculation of the difference ΔD1 and the determination value G1 is repeated using the time difference calculation data Dc1, and the total assumed sound speed Va at which the determination value G1 is equal to or less than the first threshold Th1 is the total sound speed in the region R1 other than the region of interest R2. Determined as V1.

Thereafter, in step S7, the initial value of the assumed local sound speed Vb corresponding to the region of interest R2 is set by the local sound speed determination unit 25, and the second time difference calculation data Dc2 for the region of interest R2 is acquired by the time difference calculation data acquisition unit 22. The
In step S8, the local sound speed determination unit 25 determines the difference ΔD2 based on the second time difference measurement data Dm2 and the second time difference calculation data Dc2 corresponding to the element that has received the ultrasonic echo passing through the region of interest R2. The determination value G2 is calculated, and the second time difference calculation data Dc2 acquired by the time difference calculation data acquisition unit 22 while changing the value of the local assumed sound speed Vb until the determination value G2 becomes equal to or less than the first threshold Th1. The calculation of the difference ΔD2 and the determination value G2 is repeated using, and the local assumed sound speed Vb at which the determination value G2 is equal to or less than the first threshold value Th1 is determined as the local sound speed V2 in the region of interest R2.

Further, based on the element data generated by the receiving circuit 3 by scanning the ultrasonic beam from the plurality of elements E1 to En of the array transducer 1, a B-mode image signal is generated by the image generator 4, and this B The mode image signal is output to the display control unit 5, and the ultrasonic image is displayed on the display unit 6.
The total sound speed V1 and the local sound speed V2 determined by the sound speed quantification unit 8 are output to the image generation unit 4, and the values of the total sound speed V1 and the local sound speed V2 are displayed on the display unit 6 together with the ultrasonic image. Only the value of the local sound speed V2 may be displayed instead of both the overall sound speed V1 and the local sound speed V2.

Further, based on the total sound speed V1 and the local sound speed V2 output from the sound speed quantification unit 8, the image generation unit 4 generates a B-mode image signal using the total sound speed V1 for the region R1 other than the region of interest R2. For the region of interest R2, a B-mode image signal using the local sound speed V2 can also be generated. In this way, it is possible to generate a high-quality ultrasound image in the region R1 other than the region of interest R2 and also in the region of interest R2.

In the first embodiment, the time difference measurement data acquisition unit 21 acquires the time difference measurement data Dm representing the time difference ΔT between the element data of the adjacent elements, and the time difference calculation data acquisition unit 22 acquires the time difference of the adjacent elements. Although the first time difference calculation data Dc1 and the second time difference calculation data Dc2 representing the calculation value of the time difference ΔT between the element data are acquired, the present invention is not limited to this. For example, the time difference measurement data acquisition unit 21 acquires time difference measurement data Dm representing the time difference ΔT between the element data of one element serving as a reference and the element data of another element among the plurality of elements E1 to En. Similarly, the time difference calculation data acquisition unit 22 calculates the time difference ΔT between the element data of one element serving as a reference and the element data of other elements among a plurality of elements in the region R1 other than the region of interest R2. The first time difference calculation data Dc1 representing the value and the calculation value of the time difference ΔT between the element data of one reference element and the element data of the other elements among the plurality of elements in the region of interest R2. The second time difference calculation data Dc2 can also be acquired.

Embodiment 2
In the first embodiment, the total sound speed V1 and the local sound speed V2 are quantified by transmitting and receiving ultrasonic waves only once toward one reflection point A in the subject. Thus, it is possible to quantify the total sound speed V1 and the local sound speed V2 by transmitting and receiving ultrasonic waves once each.
For example, as shown in FIG. 20, the element data obtained by transmitting and receiving ultrasonic waves once toward the reflection point Av on one scanning line Cv, and the scanning line as shown in FIG. Element data acquired by performing ultrasonic wave transmission / reception once toward the reflection point Aw on the scanning line Cw different from Cv is used.

As shown in the flowchart of FIG. 22, in the second embodiment, the region of interest R2 is set by the region of interest setting unit 17 in step S1, and in step S2, the plurality of elements E1 to En of the array transducer 1 are covered. Ultrasonic waves are transmitted / received only once toward the reflection point Av in the specimen, and element data is acquired and stored in the element data memory 7 in step S3.
In subsequent step S9, it is determined whether or not transmission / reception of ultrasonic waves to / from the plurality of set reflection points has been completed. If it is determined that transmission / reception has not been completed, the reflection point is changed in step S10, and then step S2 and S3 are repeated. That is, instead of the scanning line Cv to the scanning line Cw, ultrasonic waves are transmitted / received only once toward the reflection point Aw, and element data is acquired and stored in the element data memory 7.

If it is determined in step S9 that transmission / reception of ultrasonic waves to all reflection points has been completed, the time difference measurement data acquisition unit 21 of the sound speed quantification unit 8 corresponds to each of the reflection points Av and Aw in step S4. A comparison between a plurality of element data is performed to obtain time difference measurement data Dm, and in step S5, an initial value of the total assumed sound speed Va in the region R1 other than the region of interest R2 is set by the total sound speed determination unit 23, and a time difference calculation is performed. The data acquisition unit 22 acquires first time difference calculation data Dc1 corresponding to the region R1 other than the region of interest R2 corresponding to each of the reflection points Av and Aw.
Further, in step S6, as shown in FIG. 23, the entire sound speed determination unit 23 performs first time difference measurement data Dm1 corresponding to the region R1 other than the region of interest R2 corresponding to each of the reflection points Av and Aw. Differences ΔD1v and ΔD1w of the first time difference calculation data Dc1 are calculated, and the first difference acquired by the time difference calculation data acquisition unit 22 corresponding to each of the reflection points Av and Aw while changing the value of the overall assumed sound speed Va. The calculation of the differences ΔD1v and ΔD1w is repeated using the time difference calculation data Dc1 and the overall assumed sound velocity Va at which the differences ΔD1v and ΔD1w with respect to all the reflection points Av and Aw are minimized by using the least square method or the like. It is determined as the overall sound velocity V1 in the region R1 other than the region R2. Here, “the difference ΔD1v and ΔD1w is the smallest” means that the sum of the absolute values of the differences ΔD1v and ΔD1w in each element corresponding to the region R1 other than the region of interest R2 is the smallest, or the region of interest R2 This means that the sum of squares of the absolute values of the differences ΔD1v and ΔD1w in each element corresponding to the region R1 other than the region R1 is minimized.

Thereafter, in step S7, an initial value of the assumed local sound speed Vb in the region of interest R2 is set by the local sound speed determination unit 25, and the time difference calculation data acquisition unit 22 corresponds to the region of interest R2 corresponding to each of the reflection points Av and Aw. Second time difference calculation data Dc2 to be acquired is acquired.
Further, in step S8, the local sound speed determination unit 25 calculates the differences ΔD2v and ΔD2w between the second time difference measurement data Dm2 and the second time difference calculation data Dc2 corresponding to the reflection points Av and Aw, respectively, and the local assumption While changing the value of the sound speed Vb, the calculation of the differences ΔD2v and ΔD2w is repeated using the second time difference calculation data Dc2 acquired corresponding to each of the reflection points Av and Aw by the time difference calculation data acquisition unit 22, By using the least square method or the like, the local assumed sound speed Vb at which the differences ΔD2v and ΔD2w with respect to all the reflection points Av and Aw are minimum is determined as the local sound speed V2 of the region of interest R2. Here, “the difference ΔD2v and ΔD2w is the smallest” means that the total value of the absolute values of the differences ΔD2v and ΔD2w in each element corresponding to the region of interest R2 is minimized, or each of the elements corresponding to the region of interest R2 This means that the sum of squares of absolute values of the differences ΔD2v and ΔD2w in the element is minimized.

In step S6, the overall assumed sound speed Va at which the differences ΔD1v and ΔD1w with respect to all the reflection points Av and Aw are minimized is determined as the overall sound speed V1, but the present invention is not limited to this. For example, the reflection points Av and Determination values G1v and G1w are calculated for each reflection point based on the differences ΔD1v and ΔD1w between the first time difference measurement data Dm1 and the first time difference calculation data Dc1 with respect to Aw, and the determination values G1v and G1w are the first threshold values. An overall hypothetical sound speed Va that is equal to or less than the value Th1 is calculated as a candidate value for the total sound speed, and an average value and a mode value are calculated based on the plurality of total sound speed candidate values calculated for the plurality of reflection points Av and Aw. The overall sound speed V1 can also be determined by taking

Similarly, in step S8, determination values G2v and G2w are calculated for each reflection point based on the differences ΔD2v and ΔD2w between the second time difference measurement data Dm2 and the second time difference calculation data Dc2 for the reflection points Av and Aw, respectively. Then, the local assumed sound speed Vb at which the determination values G2v and G2w are equal to or less than the first threshold value Th1 is calculated as a local sound speed candidate value, and a plurality of local sound speeds calculated for the plurality of reflection points Av and Aw are calculated. The local sound velocity V2 can be determined by taking an average value, a mode value, or the like based on the candidate values.

Thus, by transmitting / receiving ultrasonic waves to / from a plurality of reflection points to acquire element data, the total sound speed V1 and the local sound speed V2 can be quantified with higher accuracy.

Embodiment 3
In Embodiment 1 described above, when the region of interest R2 is set by the region of interest setting unit 17, both the overall sound velocity V1 in the region R1 other than the region of interest R2 and the local sound velocity V2 in the region of interest R2 are determined. Depending on the size of the region of interest R2 set by the region-of-interest setting unit 17, the sound speed to be quantified can be selected from the overall sound speed V1 and the local sound speed V2.
The ultrasonic diagnostic apparatus according to Embodiment 3 quantifies both the total sound speed V1 and the local sound speed V2 when both the length in the scanning direction and the length in the depth direction of the region of interest R2 are larger than the set values. When at least one of the length in the scanning direction and the length in the depth direction of the region of interest R2 is equal to or less than the set value, only the total sound speed V1 is quantified without quantifying the local sound speed V2. is there.

FIG. 24 shows the operation of the ultrasonic diagnostic apparatus according to the third embodiment.
First, in step S1, the region of interest R2 is set by the region of interest setting unit 17, and in step S2, ultrasonic waves are transmitted only once from the plurality of elements E1 to En of the array transducer 1 toward the reflection point A in the subject. Transmission and reception are performed, and element data is acquired and stored in the element data memory 7 in step S3.

Thereafter, in step S11, the controller 9 determines whether or not the condition Y1 regarding the length in the scanning direction and the length in the depth direction of the region of interest R2 is satisfied. The condition Y1 is a condition that both the length in the scanning direction and the length in the depth direction of the region of interest R2 are larger than a preset set value. The set value can be, for example, a length that is 1/10 of the arrangement pitch of the plurality of elements E1 to En of the array transducer 1. When the length in the scanning direction and the length in the depth direction of the region of interest R2 are equal to or smaller than such set values, the propagation time of the ultrasonic echo that reaches the element of the array transducer 1 from the reflection point through the region of interest R2 It is difficult to accurately quantify the local sound speed V2 in the region of interest R2 because the influence of the region of interest R2 on the region is too small.

Therefore, when it is determined in step S11 that the length in the scanning direction and the length in the depth direction of the region of interest R2 are both greater than the set value and the condition Y1 is satisfied, the process proceeds to step S12, where the overall sound speed V1 and the local sound speed V1 A quantification process 100 for quantifying both the sound speeds V2 is executed. On the other hand, it is determined that the condition Y1 is not satisfied because at least one of the length in the scanning direction and the length in the depth direction of the region of interest R2 is equal to or less than the set value. If so, the process proceeds to step S13, and a quantification process 200 for quantifying only the overall sound speed V1 is executed.

In the quantification process 100, as shown in FIG. 25, in step S4, the time difference measurement data acquisition unit 21 compares the plurality of element data, and in step S5, the total sound speed determination unit 23 performs the total assumed sound speed. The initial value of Va is set, and in step S6, the overall sound speed determination unit 23 changes the value of the overall assumed sound speed Va until the determination value G1 becomes equal to or less than the first threshold value Th1, and the difference ΔD1 and the determination value G1. Is repeated, and the overall assumed sound speed Va at which the determination value G1 is equal to or less than the first threshold Th1 is determined as the overall sound speed V1 of the region R1 other than the region of interest R2. Further, in step S7, the initial value of the assumed local sound speed Vb is set by the local sound speed determination unit 25, and in step S8, the local sound speed determination unit 25 sets the local value until the determination value G2 becomes equal to or less than the first threshold value Th1. The calculation of the difference ΔD2 and the determination value G2 is repeated while changing the value of the assumed sound speed Vb, and the local assumed sound speed Vb at which the determination value G2 is equal to or less than the first threshold Th1 is defined as the local sound speed V2 of the region of interest R2. It is determined.

On the other hand, in the quantification process 200, as shown in FIG. 26, in step S4, the time difference measurement data acquisition unit 21 compares the plurality of element data, and in step S5, the total sound speed determination unit 23 performs overall comparison. An initial value of the assumed sound speed Va is set, and in step S6, the overall sound speed determining unit 23 changes the value of the overall assumed sound speed Va and the determination while changing the value of the overall assumed sound speed Va until the determination value G1 becomes equal to or less than the first threshold value Th1. The calculation of the value G1 is repeated, and the overall assumed sound speed Va at which the determination value G1 is equal to or less than the first threshold Th1 is determined as the overall sound speed V1 of the region R1 other than the region of interest R2. Note that the local sound speed V2 in the region of interest R2 is not quantified.

Further, the region of interest R2 set by the region of interest setting unit 17 is long in the scanning direction, and the region of interest R2 is selected from the plurality of straight lines connecting the reflection points in the subject and the plurality of elements E1 to En of the array transducer 1. When the passing straight line exceeds a predetermined ratio (for example, 80%), there are few elements that have received an ultrasonic echo passing through the region R1 other than the region of interest R2, and the total sound velocity V1 in the region R1 is accurately quantified. It becomes difficult to do.

Therefore, a condition where the straight line passing through the region of interest R2 out of a plurality of straight lines connecting the reflection point and the plurality of elements E1 to En of the array transducer 1 exceeds a predetermined ratio (for example, 80%) is defined as a condition Y2. As shown, if it is determined in step S11 that the length in the scanning direction and the length in the depth direction of the region of interest R2 are both greater than the set value and the condition Y1 is satisfied, in the subsequent step S14, the control unit 9 determines whether or not the condition Y2 is satisfied. If the condition Y2 is satisfied, the process further proceeds to step S15 to execute the quantification process 300 for quantifying only the local sound velocity V2.
In step S14, the condition Y2 is satisfied because the straight line passing through the region of interest R2 out of a plurality of straight lines connecting the reflection point and the plurality of elements E1 to En of the array transducer 1 is equal to or less than a predetermined ratio (for example, 80%). When it is determined not to proceed, the process proceeds to step S12, and a quantification process 100 for quantifying both the overall sound speed V1 and the local sound speed V2 is executed.

In the quantification process 300, as shown in FIG. 28, after the time difference measurement data acquisition unit 21 compares a plurality of element data in step S4, the local sound speed determination unit 25 performs local comparison in step S7. The initial value of the assumed sound speed Vb is set, and in step S8, the local sound speed determination unit 25 changes the difference ΔD2 and the determination while changing the value of the local assumed sound speed Vb until the determination value G2 becomes equal to or less than the first threshold value Th1. The calculation of the value G2 is repeated, and the assumed local sound speed Vb at which the determination value G2 is equal to or less than the first threshold Th1 is determined as the local sound speed V2 of the region of interest R2. Note that the overall sound speed V1 is not quantified.
As in the third embodiment, the sound speed to be quantified is selected from the overall sound speed V1 and the local sound speed V2 according to the size of the region of interest R2 set by the region of interest setting unit 17, and the like. Quantification of sound speed is possible.

Similarly, in the second embodiment in which the total sound speed V1 and the local sound speed V2 are quantified using a plurality of reflection points, the size of the region of interest R2 set by the region of interest setting unit 17 is also determined. The sound speed to be quantified can be selected from the overall sound speed V1 and the local sound speed V2.
Note that even if the reflection point is changed, the length in the scanning direction and the length in the depth direction of the region of interest R2 do not change. Therefore, the determination in step S11 as to whether or not the condition Y1 is satisfied is determined by a plurality of reflection points. Produces the same result. On the other hand, since the ratio of the straight line passing through the region of interest R2 among the plurality of straight lines connecting the reflection point and the plurality of elements E1 to En of the array transducer 1 varies depending on the position of the reflection point, the condition Y2 is satisfied. The determination in step S14 as to whether or not may give different results for a plurality of reflection points.

Therefore, among the plurality of reflection points, the reflection point that does not satisfy the condition Y2 in step S14, that is, a straight line that passes through the region of interest R2 when connecting the plurality of elements E1 to En of the array transducer 1 with a plurality of straight lines. When there is a reflection point with a value of 80% or less, the total sound speed V1 quantified in the quantification process 100 in step S12 for the reflection point may be adopted as the sound speed of the region R1 other than the region of interest R2. it can.

The control unit 9 determines whether or not the condition Y1 is satisfied in step S11 and whether or not the condition Y2 is satisfied in step S14. However, the present invention is not limited to this. The local sound speed determination unit 25 can also be configured to make these determinations.

In the above first to third embodiments, the total sound velocity V1 and the local sound velocity V2 are quantified using the element data output from the plurality of elements E1 to En of the array transducer 1, amplified by the receiving circuit 3, and digitized. However, the present invention is not limited to this, and the total sound speed V1 and the local sound speed V2 can be quantified using element data that has been digitized and phase-matched.

1 array transducer, 2 transmission circuit, 3 reception circuit, 4 image generation unit, 5 display control unit, 6 display unit, 7 element data memory, 8 sound velocity quantification unit, 9 control unit, 10 operation unit, 11 storage unit, 12 Amplification unit, 13 AD conversion unit, 14 signal processing unit, 15 DSC, 16 image processing unit, 17 region of interest setting unit, 21 time difference measurement data acquisition unit, 22 time difference calculation data acquisition unit, 23 global sound speed determination unit, 25 local sound speed Determining unit, V1 overall sound speed, V2 local sound speed, Va overall assumed sound speed, Vb local assumed sound speed, R1 region other than the region of interest, R2 region of interest, E1 to En, Ec, Ek, Ek + 1, Ei, Ej, Er element, Fr Adjacent element, A, Av, Aw reflection point, Cv, Cw scanning line, ΔT time difference, Dm time difference measurement data, Dm1 First time difference measurement data, Dm2, second time difference measurement data, Dc1, first time difference calculation data, Dc2, second time difference calculation data, Ti propagation time, Li, Lj1, Lj2, Lj3 distance, ΔD1, ΔD2, ΔD1v, ΔD1w difference.

Claims

An ultrasonic diagnostic apparatus that transmits an ultrasonic beam toward an object from an array transducer in which a plurality of elements are arranged, receives an ultrasonic echo from the object, and generates an ultrasonic image,
A region-of-interest setting unit that sets a region of interest on the ultrasound image;
Element data by comparing a plurality of element data output from the plurality of elements having received an ultrasonic echo reflected by the reflection point in response to transmission of an ultrasonic beam toward the reflection point in the subject A time difference measurement data acquisition unit for acquiring time difference measurement data representing a time difference between;
A time difference calculation data acquisition unit for acquiring time difference calculation data representing a time difference between element data based on a distance from the reflection point to each of the plurality of elements and a set assumed sound speed;
The first time difference measurement data acquired by the time difference measurement data acquisition unit corresponding to the element that has received the ultrasonic echo passing through the region other than the region of interest among the plurality of elements, and the overall assumption as the assumed sound velocity The difference from the first time difference calculation data acquired by the time difference calculation data acquisition unit corresponding to the element that has set the speed of sound and has received the ultrasonic echo passing through the region other than the region of interest among the plurality of elements. And an overall sound speed determining unit for determining an overall sound speed corresponding to a region other than the region of interest based on the ultrasonic diagnostic apparatus.
The overall sound speed determination unit calculates the overall assumed sound speed at which a determination value calculated based on a difference between the first time difference measurement data and the first time difference calculation data is equal to or less than a first threshold value. The ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic diagnostic apparatus is determined as a speed of sound.
3. The total sound speed determination unit according to claim 2, wherein a sum of absolute values of differences between the first time difference measurement data and the first time difference calculation data or a sum of squares of absolute values of the differences is used as the determination value. Ultrasound diagnostic equipment.
The second time difference measurement data acquired by the time difference measurement data acquisition unit corresponding to the element that has received the ultrasonic echo passing through the region of interest, a local assumed sound speed is set as the assumed sound speed, and the region of interest is A local sound speed determination unit that determines a local sound speed in the region of interest based on a difference from the second time difference calculation data acquired by the time difference calculation data acquisition unit corresponding to the element that has received the ultrasonic echo passing therethrough. The ultrasonic diagnostic apparatus according to any one of claims 1 to 3, further comprising:
The total sound speed determination unit is set by the region of interest setting unit when at least one of the length in the scanning direction and the length in the depth direction of the region of interest set by the region of interest setting unit is a set value or less. The length of the region of interest in the scanning direction and the length of the depth direction are both larger than the set value, and a straight line passing through the region of interest is predetermined among a plurality of straight lines connecting the reflection point and the plurality of elements. The ultrasonic diagnostic apparatus according to claim 4, wherein the overall sound velocity is determined only when the ratio is equal to or less than the ratio.
The local sound speed determination unit determines the local sound speed only when the length in the scanning direction and the length in the depth direction of the region of interest set by the region of interest setting unit are both larger than the set value. 5. The ultrasonic diagnostic apparatus according to 5.
The time difference measurement data acquisition unit acquires time difference measurement data representing a time difference between adjacent elements, and the time difference calculation data acquisition unit acquires time difference calculation data representing a time difference between adjacent elements. The ultrasonic diagnostic apparatus according to any one of the above.
The time difference measurement data acquisition unit acquires time difference measurement data representing a time difference between a reference element and other elements among the plurality of elements, and the time difference calculation data acquisition unit includes the reference element and The ultrasonic diagnostic apparatus according to any one of claims 1 to 6, wherein time difference calculation data representing a time difference with another element is acquired.
The time difference measurement data acquisition unit acquires the time difference measurement data for each of the plurality of reflection points by transmitting an ultrasonic beam toward the plurality of reflection points located on different scanning lines.
The time difference calculation data acquisition unit acquires the time difference calculation data for each of the plurality of reflection points,
The overall sound speed determination unit corresponds to an element that has received the ultrasonic echo passing through a region other than the region of interest among the plurality of elements, and a plurality of the first time difference measurement data with respect to the plurality of reflection points, and The overall sound velocity is determined based on a plurality of first time difference calculation data corresponding to an element that has received the ultrasonic echo passing through a region other than the region of interest among a plurality of elements and the plurality of first time difference calculation data for the plurality of reflection points. Item 9. The ultrasonic diagnostic apparatus according to any one of Items 1 to 8.
10. The total sound speed determination unit according to claim 9, wherein the total assumed sound speed at which a difference between the plurality of first time difference measurement data and the plurality of first time difference calculation data is minimized is determined as the total sound speed. Ultrasonic diagnostic equipment.
The total sound speed determination unit is configured to select a plurality of global sound speed candidates for each of the plurality of reflection points based on a difference between the first time difference measurement data and the first time difference calculation data for each of the plurality of reflection points. The ultrasonic diagnostic apparatus according to claim 9, wherein a value is calculated and the overall sound speed is determined based on the plurality of overall sound speed candidate values.
The ultrasonic diagnostic apparatus according to any one of claims 1 to 11, wherein the region-of-interest setting unit sets the region of interest as specified by a user.
The ultrasonic diagnostic apparatus according to any one of claims 1 to 11, wherein the region of interest setting unit automatically sets the region of interest from the generated ultrasonic image.
Set the region of interest on the ultrasound image,
A device that compares a plurality of element data output from a plurality of elements of an array transducer that receives an ultrasonic echo reflected by the reflection point in response to transmission of an ultrasonic beam toward the reflection point in the subject. Obtain time difference measurement data that represents the time difference between data,
Obtaining time difference calculation data representing a time difference between element data based on a distance from the reflection point to each of the plurality of elements and a set assumed sound speed;
First time difference measurement data acquired corresponding to an element that has received the ultrasonic echo passing through a region other than the region of interest among the plurality of elements, and an overall assumed sound speed as the assumed sound speed, and the plurality The total sound speed corresponding to the region other than the region of interest based on the difference from the first time difference calculation data acquired corresponding to the device that has received the ultrasonic echo passing through the region other than the region of interest A sound velocity quantification method characterized by determining