JPH04109941A - Ultrasonic wave diagnostic device - Google Patents

Abstract

PURPOSE:To obtain a good quality picture image in a short time by determining a delay compensation value only for limited focus points by a first compensation value calculating means, etermining the other focus points by the same for the other focus points by a second compensation value calculating means, and performing transmission/receiving control for a probe using obtained delay compensation values. CONSTITUTION:An ultrasonic wave diagnostic device 1 has a device main body 3 including an ultrasonic wave probe 2 having M elements, and a first and a second compensation value-calculating means 4, 5 connected with it. A designation control means 9 sets a subject measurement range, a subject interpolation range, a subject non-measurement range, etc., by an input part 8 and a CPU 7, and the first compensation value-calculating means 4 has a compensation value computation control part 24 for taking reflection signals after a signal receiving delay process from a signal receiving delay circuit 12 and performing control. The second compensation value- calculating means 5 determines a delay compensation value for the other focus points based on delay compensation values memorized in a first and a second memories 20a, 20b in the first compensation value-calculating means 4 by an interpolation process by an interpolation process part 21.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an ultrasonic diagnostic apparatus, and more specifically, to a method for reliably obtaining high-quality ultrasonic images of a target region in a short time. The present invention relates to an ultrasonic diagnostic device that can perform

(Prior Art) In conventional ultrasonic diagnostic apparatuses, so-called phasing and addition processing is performed in order to form ultrasonic beams as thin as possible inside a living body.

This is a process in which a delay amount calculated from the geometrical relative positional relationship between the focus point and each element is given to the transmission drive signal and the reception signal during transmission and reception. This results in
Since the phases of the signals emitted from each element or received by each element match near the focus point, a thin ultrasonic beam is obtained near the focus point.

However, in the phasing addition process, it is necessary to calculate the amount of delay from the geometrical relative positional relationship, and for this purpose, it is necessary to satisfy the following two conditions.

a, The sound speed of the propagation medium is − between the focus point and the element group.
Being like that.

b. The speed of sound is known.

It is thought that organs such as the liver satisfy the above two conditions to some extent, but they do not satisfy the above two conditions in the body surface layer composed of fat and muscle.

Therefore, when transmitting and receiving an ultrasound beam to and from a living body, such non-uniformity within the living body impedes phase consistency near the focus point and deteriorates the ultrasound beam.

As a result, both the spatial resolution and contrast resolution of the ultrasound image deteriorate due to this deterioration of the ultrasound beam.

In order to improve this point, there is a method to prevent deterioration of the ultrasound beam by calculating the propagation time difference between each signal from the received signal of each element and applying the delay correction value obtained from this during transmission and reception. .

By the way, as shown in FIG. 17, the propagation paths when focusing the ultrasound beam on the focus points P and Q of the living body 51 using the probe 50 with M elements are different. .

Q requires a different delay correction value.

The focus points P and Q as described above are not only two points, but actually, if the number of scanning lines of the ultrasound beam in the cross section of the living body 51 is i, and the number of focus points in each scanning line is j, then i
xj pieces, usually 1=100 to 300. j=10 to about 30, which is a very large number.

On the other hand, in order to measure the propagation time difference of the ultrasound beam due to non-uniformity of tissue within the living body 51, a reflected signal from within the living body is required.

(Problem to be Solved by the Invention) However, when determining the delay correction value for the focus point as described above, a lot of calculation processing is required just to obtain the delay correction value for one focus point. As described above, it is practically very difficult to measure the phase difference (propagation time difference) of the reflected signals received by each element for all the many focus points and use the results to obtain all the delay correction values.

In addition, there are parts of the living body where the ultrasound beam is not reflected, such as the gallbladder and blood vessels, so if the focus point as the measurement target area falls exactly on the gallbladder, etc., no reflected signal will be obtained and it will be difficult to obtain the delay correction value. There is also the problem that it is not always possible to obtain a reflected signal suitable for measurement.

Therefore, the present invention eliminates the need to measure all the phase differences of the reflected signals from many focus points on the living body to the ultrasound probe (in addition, it is possible to reliably obtain the required delay correction value in a short time and with high quality). An object of the present invention is to provide an ultrasonic diagnostic apparatus that can obtain accurate ultrasonic images.

[Structure of the Invention] (Means for Solving the Problems) The present invention solves the problem of deterioration of an ultrasound beam from an ultrasound probe due to inhomogeneity of tissue in a living body, by reducing the amount of deterioration caused by in-vivo tissue based on the ultrasound beam. In the ultrasonic diagnostic apparatus, the correction is made by detecting the phase difference of the reflected signal of the ultrasonic probe to each element in the ultrasonic probe, and correcting the transmission/reception delay time in the ultrasonic probe based on the detection result. The phase difference of the reflected signal for each element is calculated only for a limited number of focus points, which are fewer than all focus points in a large number of ultrasonic beams used when constructing a tomographic image of a specific area of a living body by driving an ultrasonic probe. a first correction value calculation means that calculates a delay correction value for the transmission/reception delay time based on the measurement result; a second correction value calculation means for calculating a delay correction value through interpolation processing using the delay correction value of a neighboring focus point calculated by the first correction value calculation means for each focus point; and displaying a tomographic image of the specific area. and a control means that controls the first and second correction value calculation means and also controls transmission and reception of the ultrasound probe.

The control means specifies the entire region or a limited arbitrary number of regions of the tomographic image displayed by the display means, and also controls the first delay correction value for the designated region. It is constituted by a designation control means that controls the second correction value calculation means and also controls transmission and reception of the ultrasonic probe.

(for production) The operation of the ultrasonic diagnostic apparatus described above will be explained below.

When each element of the ultrasound probe of this ultrasound diagnostic device is driven and an ultrasound beam is transmitted in a certain direction to a specific region of the living body, a continuous reflected signal is received by each element of the ultrasound probe. Ru.

At this time, the first correction value calculation means measures the phase difference of the reflected signal only for a limited number of focus points smaller than all focus points, and from this measurement result, a delay correction value for the transmission/reception delay time in the ultrasound probe is determined. seek.

Further, the second correction value calculation means calculates the already calculated delay correction value of the neighboring focus points for each of the remaining focus points other than the limited focus points based on the calculation result of the first correction value calculation means. Determine the delay correction value by interpolation using .

Next, the designation control means as a control means designates the entire region or a limited arbitrary number of regions of the tomographic image displayed by the display means, and calculates both of the delay correction values for the designated region. 1st. Controls the second correction value calculation means.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

The ultrasonic diagnostic apparatus 1 shown in FIG. It has second correction value calculation means 4 and 5.

The device main body 2 includes the probe 2, a multiplexer 6 for switching the transmitting/receiving elements of the probe 2, and a specification control means 9 consisting of an input section 8 consisting of a CPU 7 and a keyboard or trackball, details of which will be described later. First thing to do. a delay control section 10 that sends out a transmission control signal and a reception control signal based on the delay correction values from the second correction value calculation means 4 and 5; Transmission drive signal generation unit 11 to send out
, a reception delay circuit 12 that takes in the reception control signal and performs reception processing of the reflected signal according to a predetermined reception delay time, and an adder 1 that performs addition processing of the processing results of the reception delay circuit 12.
3, and a display control section 14 that controls the display of a display section 15 such as a cathode ray tube display based on the addition result of the addition section 13.

The designation control means 9 is configured so that a measurement target area, an interpolation process target area, a non-measurement target area, etc. can be set using the input unit 8 and the CPU 7.

The first correction value calculation means 4 includes the reception delay circuit 12
The signals from the measurement target area (usually aligned with the transmission focus point) from adjacent elements are captured in time, and the two temporally limited signals are captured. Based on the calculation results of a total of N-1 cross-correlation calculation units 16-1 to 16-(N-1) that perform cross-correlation processing and each cross-correlation calculation unit 16-1 to 16-(N-1), A total of N-1 peak detectors 17 that calculate the phase difference of the reflected signal between two elements from the peak value of
-1 to 17-(N-1) and each peak detection section 17-1
A multiplexer 18 that switches the output signals of 17-(N-1), an accumulative adder 19 that cumulatively adds the output signals of the multiplexer 18, and sends the result as a delay correction value, and processing of the accumulative adder 19. First to third memories 20a, 20b, 20 for storing results
c, the cumulative addition section 19 and the first to third memories 2
The first switch S provided between 0a, 20b, and 20c
W1, and the second. from the third memory to the delay control unit 1
A second switch SW that switches the sending of the delay correction value to 0
2, and the cross-correlation calculation units 16-1 to 16- (N-
1), peak detection units 17-1 to 17- (N-1
), multiplexer 18, cumulative adder 19. The correction value calculation controller 24 controls the first to third memories 20a to 20c.

Here, N is the number of elements that are driven to transmit and receive at the same time for scanning. Incidentally, in the case of sector scan, N=M.

The second correction value calculation means 5 is configured to calculate the first correction value. A third switch S for switching the output of the second memories 20a and 20b
W3 and an interpolation processing section 21, and this interpolation processing section 2
1 in the first correction value calculating means 4.
Second memory 20a.

Based on the delay correction values stored in 20b, delay correction values for the remaining focus points are determined by interpolation or extrapolation.

FIG. 2 shows the positions of each focus point when performing a sector scan (scanning) of a specific area of the living body using the probe 2. That is, when forming a tomographic image of a specific region, several hundred (for example, 256) scanning lines and ten to several tens of focus points are set for each scanning line.

FIG. 3 shows delay correction values necessary to correct all focus points included in the tomographic image. That is, the delay correction value means an element of a cubic matrix, which is expressed as D (n, i, D
It can be expressed as.

Here, n is the number of elements, i is the number of scanning lines, and j is the number of focus points.

FIG. 4 shows a case where a delay correction value when focusing on the (i, j)th focus point of the n-th element is determined by interpolation processing.

That is, the delay correction value D (n, i, j
) can be expressed by the following formula (1).

D (n, i, D = Σ Σ H (αL-i, β to -j) 11+l
+ 1 β −β 1S (n, αL,
βK) (1) Here, L indicates the gap between the scanning lines to be measured, and L indicates the gap between the focus points in the depth direction to be measured.

Further, S is the delay correction value obtained by the first correction value calculation means 4, H is a function for correcting the value of S in order to obtain the delay correction value, and α and β are the delay correction value S. Coordinates in scanning line change direction and focus point depth direction (n, αL, βK
) is a variable (natural number) to represent.

α1. α2. β□ and β2 are samples used for interpolation on the ij plane of the coordinates (n, i, j) of a specific focus point, that is, values representing the range of the focus point where measurement was performed.

Further, in FIG. 4, * indicates a focus point, and ■ indicates a focus point from which the delay correction value S is obtained from the first correction value calculation means 4 through measurement.

Incidentally, FIG. 5 shows the case of determining the delay correction value distribution in the scanning line direction for the n-th element.

The delay correction value D (n, i, j) in this case can be expressed by the following equation (2).

D(n, i, j) (2) Furthermore, FIG. 6 shows the case of determining the delay correction distribution in the depth direction for the n-th element.

The delay correction value D (n, i, j) in this case can be expressed by the following equation (3).

D (n, i, j) ... (3) Figures 7 (a) and (b) show the function H(i.

It is an explanatory diagram when creating j).

By finding the function H(i, j) which is the product of the function H1(t) shown in FIG. 7(a) and the function H2(j) shown in FIG. 7(b), a specific focus point can be determined. Using the samples used for interpolation in the ij plane, that is, the values representing the range of focus points where measurements were taken, the delay correction values for all focus points in the n-th element can be obtained by so-called linear interpolation, and all By performing similar processing on the elements, it is possible to obtain delay correction values for all focus points.

The above explanation is for the case where the delay correction value is obtained by measuring the phase difference of the reflected signal with respect to a certain focus point for all elements, but the above-mentioned concept of interpolation processing can also be extended between elements.

That is, the delay correction value can be expressed by the following equation (4).

H(γJ-n, αL-i, β-j)S (γ
J, αL, βK) (4) Here, J is the distance between the elements to be measured.

The γ is a variable (natural number) representing the coordinates (γJ, αL, βK) in the element direction. γ1. γ2 is a sample used for interpolating the coordinates (n, i, j) of a specific focus point, that is, a value representing the range of the focus point where measurement was performed.

This formula (4) is expressed as follows, when the number of elements with the interval J is equal to
Cross-correlation calculation units 16-1 to 16-(N-
1) Input the reflected signals from adjacent elements to 1
This means that the elements in between are not measured.

In this case, the cross-correlation calculation unit 16 for phase difference measurement
-1 to 16-(N-1) circuit scale can be reduced to 1/k.

Next, the area specification by the specification control means 9 and the display section 1
An example of the display mode of the tomographic image in 5 will be explained with reference to FIGS. 8 to 16.

First mentioned above. In order to improve the accuracy of the delay correction value obtained by the second correction value calculation means 4.5, it is necessary that the object reflecting the ultrasonic beam is suitable for measurement.

FIG. 8 is an example in which the operator specifies region A as the interpolation target region, and the first. Second correction value calculation means 4
, 5 of each scanning line in area A under the control of the CPU 7.
Calculation of the delay correction value at the focus point indicated by . and calculation of the delay correction value by interpolation processing at the focus point indicated by . are performed, respectively. In FIG. 8, the shaded area is an area where no correction is performed, and 25 is a liver parenchymal image, 22 is a blood vessel image, and 23 is a diaphragm image.

In FIG. 9, area B corresponding to the liver parenchyma 25 of each scanning line forming a tomographic image is specified as the measurement target area, only the delay correction value marked with ■ is calculated by the first correction value calculation means 4, and the remaining This is a case where the second correction value calculation means 5 calculates delay correction values by interpolation processing for all the focus points.

FIG. 10 shows that by specifying relatively small areas C corresponding to the liver parenchymal image 25 as measurement target areas, the CPU
This is a case in which an analogous area including the area C is automatically designated based on the control in step 7 and displayed on the display unit 15.

Considering that the accuracy of the analogically obtained delay correction value deteriorates as the distance from region C increases, it is highly effective to obtain the delay correction value only in the vicinity of the required region, as in the region shown in FIG.

FIG. 11 shows an example in which the operator specifies that a certain region E corresponding to the blood vessel image 22 should not be measured. For example, when the area to which measurement correction is to be performed as indicated by →← is displayed on the display unit 15 under the control of the CPU 7, if there is an area in the area indicated by →← that does not emit a reflected signal, such as a blood vessel, , region E where the operator should not measure this region
This is the case when specified as .

Note that it is possible to use various designation modes other than →←. .

FIG. 12 shows two areas F1. Specify F2, area F1
In this case, F2 indicates the area to be measured, and F2 indicates the area to be interpolated.

FIGS. 13 and 14 show areas Gl, G2 and H, respectively.
This is a case where two of 1 and 'H2 are specified, both of them are the measurement target area, and the remaining area is the interpolation target area.

The one shown in Fig. 13 is suitable for inferring the value of one measurement focus point on the same scanning line, and the one shown in Fig. 14 is suitable for inferring the value of one measurement focus point on the same scanning line. Suitable for inferring other things using point values.

FIG. 15 is an example in which one area (2) to be subjected to analogical correction is specified and one area I2 which is not to be measured is specified.

In this case, by specifying the area T1, the area to be measured is automatically determined under the control of the CPU 7, but if there is an area in that area that should not be measured, such as a blood vessel, etc. By specifying this area as area (2), the area to be measured is automatically moved under the control of the CPU 7, thereby improving the efficiency of area specification.

FIG. 16 shows three areas J□, J2. This is an example when J3 is specified.

Area J1 indicates an area for performing analogy correction, and area J2+J3 indicates an area to be measured.

In addition to the embodiments described above, the present invention can be modified in various ways within the scope of its gist.

[Effects of the Invention] According to the present invention described in detail above, with the above-described configuration, the first correction value calculation means calculates the delay correction value only for a certain limited focus point, and calculates the delay correction value for the remaining focus points. Since the delay correction value is obtained through interpolation processing by the second correction value calculation means and the transmission and reception of the probe is controlled using these delay correction values, it is possible to obtain high-quality ultrasound images in a short time. An ultrasonic diagnostic device can be provided.

Further, the designation control means designates all or a limited number of target regions, and based on the designation results, the first. Since the second correction value calculation means is controlled and the transmission and reception of the probe is controlled, an ultrasonic diagnostic apparatus is provided that can obtain ultrasonic images only of areas where reflected signals suitable for measurement can be reliably obtained. can do.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention, FIG. 2 is an explanatory diagram when sector scanning is performed using a probe of the same apparatus, and FIG. 3 is an explanatory diagram showing changes in scanning line and focus point depth. Fig. 4 is an explanatory diagram of the correction value distribution for the n-th element, Fig. 5 is an explanatory diagram of the correction value distribution in the scanning line direction for the n-th element, and Fig. 6 is an explanatory diagram of the correction value distribution for the n-th element in the depth direction. An explanatory diagram of the distribution, Figures 7 (a) and (b) are explanatory diagrams showing functions for linear interpolation, and Figures 8 to 11 are tomographic images and focus points when specifying one area each. Figures 12 to 15 are explanatory diagrams showing tomographic images and focus points when two areas are each specified, and Figure 16 is an explanatory diagram showing tomographic images and focus points when three areas are specified. FIG. 17 is an explanatory diagram showing a propagation path between a focus point in a living body and a probe element. 1... Ultrasonic diagnostic device, 2... Probe, 3...
Apparatus body, 4... First correction value calculation means, 5... Second correction value calculation means, 9... Designation control means, 15... Display section.

Claims (2)

[Claims] (1) Deterioration of the ultrasound beam from the ultrasound probe due to inhomogeneity of tissue within the body, and the phase difference between the reflected signal from the inside of the body based on the ultrasound beam and each element in the ultrasound probe. In the ultrasonic diagnostic apparatus, the ultrasonic diagnostic apparatus detects the ultrasonic probe and corrects it by correcting the transmission/reception delay time in the ultrasonic probe based on the detection result. The phase difference of the reflected signal for each element is measured only for a limited number of focus points that are fewer than all the focus points in the large number of ultrasonic beams used in the process, and from this measurement result, a delay correction value for the transmission/reception delay time is determined. a first correction value calculation means for calculating the first correction value calculation means; and a neighborhood calculated by the first correction value calculation means for each of the remaining focus points other than the limited focus points based on the calculation results of the first correction value calculation means; a second correction value calculating means for calculating a delay correction value by interpolation using the delay correction value of the focus point; a display means for displaying a tomographic image of the specific area;
, and control means for controlling the second correction value calculation means and for controlling transmission and reception of the ultrasound probe. (2) The control means specifies the entire region or a limited arbitrary number of regions of the tomographic image displayed by the display means, and also controls the first delay correction value to be determined for the designated region. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein said control means controls said second correction value calculation means and controls transmission and reception of said ultrasonic probe.