JP5255999B2 - Ultrasonic diagnostic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize a sound speed stipulating a reception delay data set (reception condition) in an ultrasonic diagnostic apparatus. <P>SOLUTION: In a test operation mode, the sound speed to be the base of computing a delay data set is changed in trial. Thus, a plurality of profiles corresponding to a plurality of reference areas are acquired. Each profile indicates the change of the evaluation value of a phasing addition result to the change of the speed. The evaluation value is equivalent to the total sum of signals after phasing addition inside the reference area for instance. One or two or more appropriate profiles are determined from the plurality of profiles, and the optimum sound speed is computed on the basis of them. The optimum sound speed is utilized as a parameter for calculating the delay data set in normal ultrasonic diagnosing. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to a technique for optimizing reception conditions.

An ultrasonic diagnostic apparatus is an apparatus that is used in the medical field and forms an ultrasonic image by transmitting and receiving ultrasonic waves to and from a living body. Ultrasonic wave transmission / reception is normally performed by an array transducer (a 1D array transducer, a 2D array transducer, or the like) composed of a plurality of transducer elements. Specifically, at the time of transmission, a plurality of transmission signals having a transmission delay relationship corresponding to the transmission focus point are supplied to the array transducer, thereby forming a transmission beam. At the time of reception, the reflected wave (echo) from the living body is received by the array transducer, and the phasing addition processing according to the reception delay condition is executed on the plurality of reception signals from the array transducer, thereby Thus, a reception beam is formed. An ultrasonic image is formed based on the plurality of beam data after the phasing addition. Note that, at the time of reception, reception dynamic focus is generally applied in which the reception focus point is dynamically changed from a short distance to a deep direction along the beam axis.

The phasing addition processing in the receiving unit will be described in detail. For the delay processing of a plurality of received signals, the receiving unit is given delay data (delay time set) that defines the delay condition from the control unit. The delay data is data for realizing reception dynamic focus and reception beam scan, and is configured by a data set corresponding to a plurality of reception channels or a plurality of vibration elements. In calculating the delay data, a constant value is usually adopted as the sound speed in the living body, and for example, it is 1530 m / s.

Japanese Patent Laid-Open No. 3-146039 JP-A-8-317926 JP-A-5-329159 JP 2008-264531 A

However, the speed of sound of ultrasonic waves in a living body actually changes depending on the properties of the tissue in the living body.
If delay data is configured on the premise of uniform sound speed, an appropriate reception focus condition cannot be realized depending on an actual diagnosis situation, and there arises a problem that reception sensitivity and image resolution are lowered. In this regard, in Patent Document 1, the sound speed coefficient is changed on a trial basis, the echo level of the ultrasonic video signal (echo signal received by the probe) is detected, and the sound speed coefficient that maximizes the echo level is obtained. An ultrasonic diagnostic apparatus that obtains delay data of a transmission unit and a reception unit based on this is disclosed. This Patent Document 1 also describes detecting an echo level for an arbitrary depth or range in a subject. However, if the echo level changes irregularly with the change in the sound speed coefficient, an inappropriate sound speed may be set. Patent Document 2 discloses an ultrasonic diagnostic apparatus that obtains an optimum sound speed value at a time point when the maximum value is reached based on a received signal amplitude value that changes with a change in sound speed by an operator. Also in this case, if the received signal amplitude value does not draw a beautiful maximum curve with the change in the sound speed, an inappropriate sound speed may be adopted. Patent Document 3 describes an ultrasonic diagnostic apparatus that obtains a plurality of images with different focus patterns and selects an image in an optimal focus state based on the feature amount of those images. In the ultrasonic diagnostic apparatus described in Patent Document 4, a curve representing a change in contrast value when a sound speed for delay data calculation is changed is generated for each region on the scanning plane. And the optimal sound speed about each area | region is calculated | required from the maximum value in each curve. Here, it is presumed that the contrast value represents the difference between light and dark, and it is recognized that it is not necessarily information indicating the quality of the phasing addition result itself. This document also describes that when a plurality of sound velocities are obtained for a plurality of regions, an average value thereof is obtained as the optimum sound speed (Example 3). However, since it is not determined whether or not the curve is appropriate for each region, there is a possibility that a problem occurs in the reliability of the optimum sound speed.

  An object of the present invention is to provide an ultrasonic diagnostic apparatus capable of optimizing reception delay conditions.

Another object of the present invention is to provide an ultrasonic diagnostic apparatus capable of optimizing reception delay conditions based on reliable information.

An ultrasonic diagnostic apparatus according to the present invention includes an array transducer including a plurality of transducer elements for forming an ultrasonic beam, and a phasing addition of a plurality of reception signals from the array transducer in accordance with a set delay condition. And a sound speed calibration means for performing sound speed calibration as a parameter for defining a delay condition during a test operation, and the sound speed calibration means is configured to scan the ultrasonic beam. Reference region setting means for setting a plurality of reference regions in a three-dimensional or three-dimensional scanning region, and a trial delay condition setting for sequentially setting a plurality of trial delay conditions corresponding to a plurality of sound velocities for the receiver And the phasing addition result when the trial delay condition is changed for each reference region based on the received signal after the phasing addition Profile generation means for generating a profile representing a change in evaluation value, determination means for determining one or more appropriate profiles from among a plurality of profiles corresponding to the plurality of reference regions, and the one or more appropriate profiles. And an optimum sound speed calculating means for calculating an optimum sound speed that defines a delay condition to be used during normal operation.

According to the above configuration, the sound speed calibration is executed before or during the normal operation (ultrasound diagnosis). In the sound speed calibration, the sound speed (sound speed parameter) that defines the reception delay condition is adapted to the actual living tissue. Therefore, the sound velocity calibration is executed under a situation where ultrasonic waves are transmitted / received to the living body, and preferably the sound velocity calibration is executed when the probe is brought into contact with the subject. Of course, a plurality of sound velocity calibrations are executed according to the type of the subject (for example, body type, physique) and the diagnosis site, and a plurality of optimum sound speeds are preset, and in actual ultrasonic diagnosis, the type of the subject The optimum sound speed to be actually used may be selected from a plurality of preset optimum sound speeds with different diagnosis parts or the like. Conventionally, a fixed value is used as the sound speed. However, if the delay condition is obtained using the sound speed (optimum sound speed) according to the subject, the sensitivity can be increased, or the resolution of the ultrasonic image can be increased.

The reference area setting means sets a plurality of reference areas (sub-ROIs) in the scanning area. A plurality of reference regions may be set in a matrix or may be set discretely. There may be partial overlap with each other.
A plurality of reference areas may be set over the entire scanning area, or a plurality of reference areas may be set in a part (for example, the central portion) of the scanning area. A single reference area may be set, but in that case, the optimum sound speed is likely to be greatly influenced by the setting location of the reference area, and an inappropriate sound speed may be calculated as the optimum sound speed. Increase. On the other hand, if a plurality of reference areas are set, a plurality of profiles can be obtained and appropriate ones can be selected and used. The trial delay condition setting means is configured to trially set a plurality of delay conditions corresponding to a plurality of sound speeds for the receiving unit. A delay condition corresponding to a sound speed scan may be scanned, or the delay conditions may be set in a predetermined order. The delay condition may be switched in units of one beam scan, or the delay conditions may be switched in units of a plurality of beam scans. Alternatively, the delay condition may be switched in units of one or a plurality of beams. As a result, the beam scanning and the trial switching of the sound velocity for calculation are executed so that a plurality of profiles corresponding to a plurality of reference regions are obtained. The reference area is preferably a two-dimensional or three-dimensional area, but can be a one-dimensional area.

The profile generation means generates a profile for each reference area. The profile represents a change in evaluation value with respect to a change in sound speed. Desirably, the horizontal axis of the coordinate system in which the profile is represented represents the speed of sound, and the vertical axis represents the evaluation value. The evaluation value is obtained from the received signal after the phasing addition, and is preferably the sum or average value of the signal intensities in one reference region. Here, the signal strength is preferably amplitude or power. An RF signal before detection may be evaluated, or an envelope signal after detection may be evaluated. Desirably, the signal prior to image formation (ie, scan conversion) is evaluated. The present invention evaluates the phasing addition result in view of the best reception focus if the sound speed used in the calculation of the delay data is optimal, that is, the signal level after phasing addition increases. . Since interpolation processing or the like is applied at the time of image formation, it is difficult to faithfully evaluate the phasing addition result at that stage. Therefore, it is desirable to evaluate the signal immediately after the phasing addition.

When a plurality of profiles corresponding to a plurality of reference regions are obtained, one or more appropriate profiles are determined by the determination means. This eliminates an inappropriate profile and increases the reliability of sound speed calculation. In view of the principle of phasing addition, the evaluation value for the phasing addition result is optimal at the optimum sound speed, and the evaluation value typically decreases as it moves back and forth (that is, it has a mountain shape). Therefore, it is desirable to determine whether or not there is an effective maximum as a criterion for determining an appropriate profile. When the profile exhibits a tendency such as monotonous increase, monotonous decrease, or poor level change, it is desirable to exclude the profile from being calculated as inappropriate.

As described above, when one or more appropriate profiles are obtained, the appropriate sound speed calculation means
The appropriate sound speed is calculated based on one or more appropriate sound speeds obtained from them. For example, when each sound speed corresponding to the effective maximum (maximum value) of each profile can be regarded as an appropriate sound speed, the optimum sound speed is obtained as an average value of a plurality of appropriate sound speeds. The optimum sound speed determines the delay condition to be used during normal operation thereafter. A plurality of delay conditions (that is, a plurality of delay data sets) may be prepared in advance, and a delay condition corresponding to the optimum sound speed may be selected from the delay conditions and set in the receiving unit. At that time, the optimum delay condition may be calculated immediately and then set in the receiving unit. In the present invention, the sound speed may be a sound speed in a physical sense, but may be information (such as a coefficient) corresponding to such a sound speed.

The optimum sound speed may be used for setting a reception delay condition, setting a transmission delay condition, setting a conversion condition at the time of image formation, setting a measurement condition, and the like. Since the sound speed that defines the reception delay condition is not a fixed value as in the prior art, if necessary, information indicating the optimum sound speed may be provided to the user. Alternatively, the information may be recorded together with the reception data and the ultrasonic image.

Preferably, the determination means checks whether or not there is an effective maximum for each profile, and determines that a profile having an effective maximum is an appropriate profile. Preferably, a plurality of determination conditions are defined in order to check whether or not the effective maximum exists.
The plurality of determination conditions include a first determination condition for determining whether or not the sound speed corresponding to the maximum is within the first range, and a second determination for determining whether or not the evaluation value corresponding to the maximum is within the second range. And conditions. Desirably, the plurality of determination conditions further include a third determination condition for determining whether the degree of change in the evaluation value in the profile is larger or smaller than a predetermined value. As a result, it is desirable to exclude profiles that tend to monotonically increase, monotonously decrease, evaluation value fluctuation is insufficient, and evaluation value is indefinite.

Preferably, the evaluation value for the phasing addition result corresponds to a total value or an average value of received signals after phasing addition in each reference region. Preferably, the optimum sound speed calculation means is
When the determination unit determines a plurality of appropriate profiles, a plurality of appropriate sound velocities corresponding to a plurality of effective maximums in the plurality of appropriate profiles are obtained, and the optimum sound speed is calculated based on the appropriate sound speeds. In that case, the optimum sound speed may be determined as an average value of a plurality of appropriate sound speeds. Desirably, the optimal sound speed calculating means obtains an appropriate sound speed corresponding to an effective maximum in the appropriate profile when the determining means determines one appropriate profile, and sets it as the optimal sound speed. In addition, when one appropriate profile cannot be determined, an error may be output and the standard sound speed may be used as it is.

Preferably, the profile generation unit generates a profile for each reference region by generating an approximate curve based on a plurality of evaluation values corresponding to the plurality of trial delay conditions. According to this configuration, a significant profile can be acquired even if the number of sound speeds set on a trial basis is small. Preferably, the information processing apparatus includes means for displaying or recording information indicating an optimum sound speed calculated during the test operation during execution of the ultrasonic diagnosis during the normal operation. Although it is possible to calculate the optimum sound velocity for each part of the scanning area individually, it is possible that the ultrasonic image is distorted or the uniformity of image quality is impaired in that case. It is desirable to set a unique (single) optimum sound speed throughout the region. It is also possible to obtain the optimum sound speed in real time while performing an ultrasonic diagnosis, but when the sound speed is changed on a trial basis, the image quality of the ultrasonic image cannot be guaranteed. It is desirable that the sound velocity calibration is executed at the timing (in the middle of ultrasonic diagnosis).

As described above, according to the present invention, the delay condition can be optimized by evaluating the signal after phasing addition while changing the sound speed (sound speed parameter) defining the delay condition on a trial basis.
In particular, since a plurality of reference areas are used, the reliability can be improved.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

FIG. 1 shows a preferred embodiment of an ultrasonic diagnostic apparatus according to the present invention, and FIG. 1 is a block diagram showing the overall configuration thereof. This ultrasonic diagnostic apparatus is used in the medical field,
It is an apparatus that forms an ultrasonic image by transmitting / receiving ultrasonic waves to / from a living body.

In FIG. 1, an array transducer 10 is provided for a probe not shown. The array transducer 10 is composed of a plurality of transducer elements 10a. An ultrasonic beam is formed by the array transducer 10, and the ultrasonic beam is electronically scanned. As electronic scanning methods, electronic sector scanning, electronic linear scanning, and the like are known. The array transducer 10 is a 1D array transducer, but a 2D array transducer may be provided instead to scan the ultrasonic beam two-dimensionally. In the present embodiment, the ultrasonic beam is scanned one-dimensionally, thereby forming a two-dimensional scanning plane.

The transmission unit 12 is a transmission beam former, and during transmission, the transmission unit 12 supplies a plurality of transmission signals to the array transducer 10 in parallel. As a result, a transmission beam is formed. On the other hand, at the time of reception, the reflected wave from the living body is received by the array transducer 10, and a plurality of reception signals from the array transducer 10 are output to the receiving unit 14 in parallel. The receiving unit 14 is a receiving beam former.

Specifically, the receiving unit 14 includes a plurality of A / Ds provided corresponding to the plurality of vibration elements 10a.
A converter 16, a memory 18 such as a FIFO provided corresponding to the plurality of vibration elements 10 a, and an adder 20 are included. Note that an amplifier or the like provided for each reception channel is not shown. The receiver 14 constitutes a so-called digital beam former,
Echo data for one ultrasonic beam is stored in the memory for each reception channel, and the echo data is read out from the memory with a delay time according to the delay data and then received by adding multiple echo data. A received signal corresponding to the beam is obtained.
That is, the phasing addition process is executed in the receiving unit 14, and in that case, delay data is provided for each receiving channel, and delay data sets corresponding to a plurality of receiving channels are supplied from the control unit 30. . The ultrasonic beam is a beam obtained by combining the transmission beam and the reception beam, and transmission beam focus control is executed at the time of transmission, and reception dynamic focus control is executed at the time of reception.

When the phasing addition processing is executed in the receiving unit 14, the receiving signal (RF signal) after the phasing addition is output from the receiving unit 14. The received signal is input to the detector 22, and the detection process is performed on the received signal in the detector 22, thereby converting the received signal into a baseband region received signal. The received signal output from the detector 22 is processed by a beam data processing unit (not shown), and the processed signal is input to a digital scan converter (DSC) 24. The DSC 24 has a coordinate conversion function, an interpolation processing function, and the like, and forms an ultrasonic image (two-dimensional tomographic image) based on a plurality of beam data. The image data is sent to the display unit 28 via the display processing unit 26. The display unit 28 displays a two-dimensional tomographic image as an ultrasonic image. In FIG. 1, a circuit for processing Doppler information and the like are not shown.

The control unit 30 performs operation control of each configuration shown in FIG. 1, and is configured by a CPU and an operation program. In the present embodiment, the control unit 30 functions as a transmission / reception control unit. The ultrasonic diagnostic apparatus according to the present embodiment has a test operation mode for performing speed calibration in addition to a normal operation mode. The control unit also has a function of performing control in the test operation mode, which is depicted as a test operation control unit 32 in FIG. The specific control content will be described in detail later.

An operation panel 34 is connected to the control unit 30, and the operation panel 34 includes a keyboard, a trackball, and the like. The user can instruct execution of speed calibration using the operation panel 34. The speed calibration, that is, the test operation mode is executed before performing the normal ultrasonic diagnosis, or is executed by a predetermined operation of the user during the normal ultrasonic diagnosis.

FIG. 1 shows a configuration 35 for performing speed calibration as a block diagram. Specifically, an area division unit 36, a profile generation unit 38, a suitability determination unit 40, an optimum sound speed calculation unit 42, and a test operation control unit 32 are shown. They function when performing the speed calibration, and each configuration will be described in detail below.

The area dividing unit 36 is a module that sets a plurality of reference areas (sub-ROIs) on the scanning plane and extracts a signal corresponding to each reference area in the received signal, as will be described later with reference to FIG. The plurality of reference regions may have the same size and shape, or the size and shape may be different among the plurality of reference regions.

The profile generation unit 38 is a module that generates a plurality of profiles corresponding to a plurality of reference areas. The profile is generated from the received signal corresponding to the reference area. In the present embodiment, the predetermined evaluation when the sound speed for delay data calculation is changed on a trial basis, that is, when the reception condition is changed. A profile is generated as a change in value, and the predetermined evaluation value is a sum of signal intensities in the reference region. That is, the evaluation value is obtained by integrating the phasing addition results in the reference region. If the phasing addition is properly performed and the phases between the plurality of received signals are ideally aligned, the maximum amplitude can be obtained, that is, the phasing addition result becomes the maximum value. On the other hand, if the phasing addition process is inappropriate, the phasing addition result is at a low level. From such a viewpoint, the profile is configured to indicate the quality of the phasing addition result when the sound speed that is the basis for calculating the delay condition is changed by using the sum of the phasing addition results as an evaluation value. It becomes possible. An example of the profile will be described later with reference to FIG.

The suitability determination unit 40 determines whether or not each of the plurality of profiles generated corresponding to the plurality of reference regions is an appropriate profile. In the present embodiment, a plurality of conditions are defined as determination conditions, and a profile that satisfies these conditions is determined to be an appropriate profile.

The optimum sound speed calculation unit 42 is a module that calculates the optimum sound speed based on one or more appropriate speeds obtained from one or more appropriate profiles. Specifically, when a plurality of appropriate profiles are obtained, an average value of a plurality of appropriate speeds corresponding to the profiles is obtained, and the average value is regarded as the optimum sound speed. The calculated optimum sound speed is passed to the control unit 30 for delay data calculation.

The control unit 30 has a function of calculating a delay data set based on the optimum sound speed. The delay data set defines a delay time difference between a plurality of received signals. Specifically, the delay data set defines a read timing for each memory. In this embodiment, the delay data set is calculated based on the optimum sound speed. However, if a plurality of delay data sets corresponding to a plurality of sound speeds are obtained in advance and the optimum sound speed is calculated, the corresponding delay data set is calculated. A data set may be selected immediately.

In this embodiment, the reception delay data set is calculated. However, the transmission delay data set may be further calculated. The area dividing unit 36 shown in FIG.
Although the profile generation unit 38, the suitability determination unit 40, and the optimum sound speed calculation unit 42 can be configured as dedicated hardware, they may be realized as software functions.

FIG. 2 shows an example of setting a plurality of reference areas. A region of interest 46 is set on the scanning plane 44, and the region of interest is divided into a plurality of reference regions (sub-ROI) 48-1 to 48-6. Here, the number m in the horizontal direction and the number n in the vertical direction of the reference region array can be arbitrarily determined by the user. In the figure, m = 3 and n = 2.

In the example shown in FIG. 2, a plurality of reference areas are set at the center of the scanning surface 44.
A plurality of reference areas may be set over the entire scanning surface 44. In the test operation mode, the ultrasonic beam may be scanned within a range in which a plurality of reference areas are covered. That is, during normal operation, the ultrasonic beam B is scanned and the scanning surface 4
However, in the test operation mode, the ultrasonic beam B may be scanned only in the section covering the plurality of reference regions 48-1 to 48-6 to perform the rapid processing. Incidentally, the x direction is the scanning direction of the ultrasonic beam, and the y direction is the depth direction. In FIG. 2, a rectangular scanning surface 44 formed by electronic linear scanning is shown. However, when electronic sector scanning is applied, a fan-shaped scanning surface is formed.

In FIG. 2, the reference regions 48-4 and 48- are included in the reference regions 48-1 to 48-6.
For 6, the boundary between the two tissues appears prominently. If such a reference area is used as the basis for calculating the optimum speed, the sound speed to be set may not be optimized. Therefore, in the present embodiment, the optimum speed is calculated based on the appropriate sound speed obtained from the remaining reference areas excluding those reference areas. The determination as to which reference area is appropriate is made by examining the form of the profile.

FIG. 3 shows an example of a profile. The horizontal axis represents the speed c set on a trial basis, and the vertical axis represents the evaluation value A (c). Here, the evaluation value A (c) corresponds to the sum of signals after phasing addition in the reference region. A profile 100 is obtained in which the evaluation value is plotted while changing the speed c on a trial basis, that is, while changing the reception delay condition. The profile 100 shown in FIG. 3 has a mountain shape, and the maximum value 100A is the maximum value.
One has occurred. That is, it is possible to confirm that the phasing addition condition is optimized at such a peak. It is possible to recognize the appropriate rate C _P as a speed that caused such maxima 100A. That is, during the test operation, the speed c, which is the basis for the calculation of the delay data set, is changed stepwise, and transmission / reception of ultrasonic waves is performed using the delay data set calculated based on that for each speed. That is, a beam scan is executed, an evaluation value that is a phasing addition result obtained at that time is plotted, and a profile 100 is generated by repeating the process, and the maximum 100A is specified in such a profile 100. it makes the most appropriate speed C _P is found as a result. Actually, a plurality of profiles are obtained, and an appropriate speed _CP is calculated for each of them, so that the optimum sound speed is obtained as an average value thereof. Such optimum sound speed is used as a parameter when calculating the delay data set during normal operation.

In FIG. 3, C1 and C2 represent the lower limit and the upper limit of the effective range on the horizontal axis. A1 and A2 represent the lower and upper limits of the effective range on the vertical axis. It is determined whether or not the profile is appropriate using the effective range on the horizontal axis and the effective range on the vertical axis. In the present embodiment, the rate of change described in detail later is calculated for each profile. If the rate of change is smaller than a certain value, it is determined that the profile is inappropriate. Below, the determination method about a profile is explained in full detail.

In FIG. 4, two improper profiles are shown. Profile 102 shown in (A)
, The maximum occurs on the lower side of the lower limit C1 on the horizontal axis, that is, there is no effective maximum within the effective range. In such a case, it is determined that the profile is inappropriate. Even if the maximum value is recognized but the monotonic decreasing characteristic, it is determined that the profile is inappropriate. In the profile 104 shown in FIG. 4B, the maximum occurs at a position higher than the upper limit C2 on the horizontal axis. Such a profile 104 is determined to be an inappropriate profile. Even when the maximum value is recognized, the profile is determined to be an inappropriate profile even when the monotonically increasing characteristic is obtained.

5A to 5C show other inappropriate profiles. In the profile 106 shown in (A), the maximum value on the profile is lower than the lower limit A1 on the vertical axis. Therefore, such a profile is determined to be an inappropriate profile. As a result, it is possible to exclude a noise level profile or a profile left in the air from the calculation target. In the profile 108 shown in (B), the maximum value of the profile exceeds the upper limit A2, and it is determined that such a profile 108 is also an inappropriate profile. That is, it is recognized that it is not appropriate to use a profile that is saturated as a basis for calculating the optimum speed. In such a case, it is determined that the profile is an inappropriate profile. Profile 110 shown in (C)
As for, the maximum value exists between the lower limit A1 and the upper limit A2 on the vertical axis, and when viewed microscopically, it is recognized that the local maximum is within the effective range on the horizontal axis, but such a profile is too Since it is too flat, it is determined that the profile is inappropriate based on the rate of change of the profile.

As described above, by setting the effective range on the vertical axis and the effective range on the horizontal axis, and using the rate of change or the degree of change as a criterion, a reference that should actually be referenced in multiple reference areas Only the profile corresponding to the region can be regarded as the appropriate profile, and as a result, the calculation accuracy of the optimum speed can be improved.

Incidentally, with respect to A1 and A2 above, when the effective range is 5% in the positive and negative directions from the standard sound speed 1530 m / s in the living body,
1455 m / s may be set, and 1605 m / s may be set as A2.

Next, a test operation in the ultrasonic diagnostic apparatus according to the present embodiment will be described with reference to FIGS.

FIG. 6 shows the main routine. In S301, it is determined whether or not sound speed resetting (sound speed calibration) is executed prior to normal operation (ultrasound diagnosis). When the user operates a predetermined switch, S302 is executed. In S302,
Each process of FIG. 7 thru | or FIG. 9 mentioned later is performed. As a result, the optimum sound speed is obtained, and the reception condition (delay data set) is recalculated or the reception condition is selected based on the optimum sound speed. The optimum sound speed may be used for calculation of transmission conditions, or may be used for image formation or measurement. If it is determined in S301 that the sound speed is not reset, S303 is immediately executed, and the normal operation is executed. In normal operation, when the user operates a predetermined switch, sound speed calibration may be executed as an interruption process (see A in FIG. 6).

7 and 8 show a specific example of the sound speed calibration shown in S302 of FIG. In S101, initial setting is executed. That is, the starting sound speed (scan initial value) is substituted for the variable c representing the sound speed set on a trial basis, zero is substituted for the maximum search variable C _P (n), and the maximum value search variable MaxA (n ) Is substituted with zero, and the minimum value search variable MinA (
Infinity (that is, the maximum value that the variable can take) is assigned to n). Here, n represents a reference area, that is, a sub ROI number.

In S102, it is determined whether c exceeds the end sound speed (scan end value). If not, S103 and subsequent steps are executed. In S103, a delay condition (delay data set for phasing addition) is calculated based on c currently set on a trial basis. Of course, a delay condition to be used on a trial basis may be selected from a plurality of delay conditions that have already been calculated. When the delay condition is set, scanning of the ultrasonic beam is performed. For example, one ultrasonic beam scan is executed per delay condition (that is, the speed of sound). In S104, 1 is substituted into the variable n, and in S105, it is determined whether n is N or less. Here, N is the number of reference regions, that is, sub-ROIs. The following loop from S106 to S109 is executed N times.

In S106, the evaluation value A (c, n) is acquired for the nth reference region. In this embodiment, A (c, n) is the total sum (echo data integrated value) of signals after phasing addition in the nth reference region when the sound speed c is set on a trial basis. . However, other information may be used as the evaluation value as long as the quality of the phasing addition result can be determined. In S107, if A (c, n) is greater than or equal to MaxA (n), A (c, n) is assigned to MaxA (n), and A (c, n) is substituted.
And the current c is substituted into C _P (n). In S108, if A (c, n) is equal to or smaller than MinA (n), A (c, n) is substituted into MinA (n). In this manner, after the update process for the variable for maximum value search and the variable for minimum value search is executed, n is incremented in S109. Therefore, in a situation where a certain sound speed c is set, when the loop from S106 to S109 is executed N times, n evaluation values are obtained for n reference areas. When n exceeds N, the process proceeds from S105 to S110. In S110, the increment step is added to the current c, and c is updated. And the process after S102 is performed again. At the stage where c exceeds the end sound speed by repeating the loop from S103 to S110, profiles are obtained for all reference regions. However, for each reference area,
It is desirable to generate (shape) a profile as a smooth curve by applying a spline interpolation process or the like to a plurality of evaluation values corresponding to a plurality of sound speeds. Such a process is provided, for example, between S102 and S111. Such an interpolation process can be executed at any timing between S102 and S118. For example, between S102 and S111, between S117 and S118, and between S112 and S115.
May be executed between. From the viewpoint of increasing the efficiency of the arithmetic processing, S117 and S11
It is desirable that an interpolation process is executed between

In the process shown in FIG. 7, a plurality of evaluation values corresponding to a plurality of reference areas are obtained at each stage while increasing c in stages, but the reference area to be calculated is changed in stages. However, c may be changed from an initial value to an end value at each stage. If a plurality of profiles corresponding to a plurality of reference regions are obtained as a result, the sequence for obtaining them has a degree of freedom. However, according to the method shown in FIG. 7, since necessary information can be sequentially acquired in the process of repeatedly performing beam scanning, it is possible to expect rational and quick processing.

After S111, the rate of change RA (n) is calculated for each profile. Specifically, 1 is substituted for n in S111, and it is determined whether or not n is N or less in S112. If N or less, the rate of change R in S113 according to the following formula:
A (n) is calculated.

RA (n) = [MaxA (n) −MinA (n)] / MaxA (n)
The above change rate represents the degree of difference in height of the nth profile, and other parameters may be used as a determination criterion if it can be determined that the gradient of the profile is very poor. In S114, n is incremented and each process after S112 is repeatedly executed. If it is determined in S112 that n exceeds N, S shown in FIG.
Each process after 115 is executed.

In FIG. 8, in S115, an initial setting for determining whether or not the profile is appropriate is made. Specifically, the variable C _x for searching for the maximum (effective maximum) that is the maximum value that satisfies a certain condition.
Is substituted with zero, and zero is substituted into the variable M for investigating the number of appropriate profiles,
1 is substituted for n. In S116, it is determined whether or not n is equal to or smaller than N. If it is equal to or smaller than N, whether or not the nth profile is appropriate is determined in S117. This will be described later with reference to FIG. If the profile of interest is determined to be NG, that is, if it is an inappropriate profile, the process proceeds to S119. If the profile of interest is determined to be OK, that is, if it is an appropriate profile, the process is performed. The process proceeds to S118, where C _P (n) is added to the current C _x , and the addition result is newly set to C _x and the calculation to increment M is executed. In step S119, n is incremented. That is, the suitability of the first to Nth profiles is determined in order. The number of appropriate profiles can be recognized as the value of M. The final C _x is a cumulative value of the speed corresponding to an effective maximum with proper profiles. The accumulated value is for calculating an average value described later.

If it is determined in S116 that n exceeds N, it is determined in S120 whether or not M is 1 or more, that is, whether or not at least one appropriate profile has been acquired. In S121, by dividing the C _x with M, optimal speed (the optimum value) is calculated as an average value of the proper speed. In S122, the optimum speed is output to the control unit. On the other hand, if the proper profile is not obtained, an error is notified in S123, and the standard speed (specified speed) as in the conventional case is used as the optimum speed.

FIG. 9 shows an operation example performed in S117 of FIG. In S201, it is determined whether the speed C _P (n) corresponding to the maximum value MaxA (n) in the profile of interest is within or outside the effective range on the speed axis. For example, in the case shown in FIGS. 4A and 4B, it is determined that the profile is inappropriate. That is, if the speed C _P (n) is outside the effective range on the speed axis, it is determined as NG, and otherwise it is determined as OK. In S202,
It is determined whether the maximum value MaxA (n) in the profile of interest is within or outside the effective range on the evaluation value axis. For example, in the case shown in FIGS. 5A and 5B, it is determined that the profile is inappropriate. That is, if the maximum value MaxA (n) is outside the effective range on the evaluation value axis, it is determined as NG, and otherwise it is determined as OK. In S203
It is determined whether the rate of change RA (n) in the profile of interest is smaller or larger than a predetermined determination value (effective value). For example, in the case shown in FIG. 5C, it is determined that the profile is inappropriate. That is, if the rate of change RA (n) is smaller than the predetermined determination value, it is determined as NG, and otherwise it is determined as OK.

As described above, a plurality of reference areas are set on the scanning plane, a plurality of profiles are acquired, an appropriate profile is selected, and an optimum sound speed is calculated based on the selected profile. It can be obtained. As a result, the reception delay condition can be improved.
Sensitivity can be improved or resolution can be increased. In the above embodiment, the RF (high frequency) signal after phasing addition is referred to, but the signal after detection may be referred to.

1 is a block diagram showing an overall configuration of an ultrasonic diagnostic apparatus according to the present invention. It is a figure for demonstrating the setting of a some reference area. It is a figure which shows an example of a suitable profile. It is a figure which shows the example of an improper profile. It is a figure which shows the other example of an improper profile. It is a figure which shows the main routine of the ultrasonic diagnosing device which concerns on this embodiment. It is a figure which shows the execution process of speed calibration. It is a figure which shows the execution process of speed calibration. It is a figure which shows the specific operation example of S117 shown in FIG.

Explanation of symbols

10 array transducers, 12 transmitting units, 14 receiving units, 30 control units, 32 test operation control units, 36 area division units, 38 profile generation units, 40 suitability determination units, 42 optimum sound speed calculation units, 100, 102, 104, 106,108,110 profiles.

Claims (7)

An array transducer composed of a plurality of transducer elements for forming an ultrasonic beam;
In accordance with a set delay condition, a receiving unit that performs phasing addition of a plurality of reception signals from the array transducer,
A sound speed calibration means for performing a sound speed calibration as a parameter for defining a delay condition during a test operation;
Including
The sound velocity calibration means includes
Reference region setting means for setting a plurality of reference regions in a two-dimensional or three-dimensional scanning region scanned by the ultrasonic beam;
Trial delay condition setting means for sequentially setting a plurality of trial delay conditions corresponding to a plurality of sound speeds for the receiving unit;
Profile generating means for generating a profile representing a change in an evaluation value for a phasing addition result when the trial delay condition is changed for each reference region based on the received signal after the phasing addition;
Determination means for determining one or a plurality of appropriate profiles from a plurality of profiles corresponding to the plurality of reference regions;
Based on the one or more appropriate profiles, optimum sound speed calculating means for calculating an optimum sound speed that defines a delay condition to be used during normal operation;
Only including,
The determination means examines whether or not there is an effective maximum for each profile, determines that a profile having an effective maximum is an appropriate profile,
In order to check whether or not the effective maximum exists, a plurality of determination conditions are defined,
The plurality of determination conditions include a first determination condition for determining whether or not the sound speed corresponding to the maximum is within the first range, and a second determination for determining whether or not the evaluation value corresponding to the maximum is within the second range. and conditions include, ultrasonic diagnostic apparatus characterized by. The apparatus of claim 1 .
The ultrasonic diagnostic apparatus characterized in that the plurality of determination conditions further include a third determination condition for determining whether the degree of change in the evaluation value in the profile is larger or smaller than a predetermined value. The apparatus according to claim 1 or 2 ,
The ultrasonic diagnostic apparatus according to claim 1, wherein an evaluation value for the phasing addition result corresponds to a total value or an average value of reception signals after phasing addition in each reference region. The device according to any one of claims 1 to 3 ,
The optimum sound speed calculating means obtains a plurality of appropriate sound speeds corresponding to a plurality of effective maximums in the plurality of appropriate profiles when the determining means determines a plurality of appropriate profiles, and based on the appropriate sound speeds An ultrasonic diagnostic apparatus characterized by calculating an optimum sound speed. The apparatus of claim 4 .
The optimum sound speed calculation means obtains an appropriate sound speed corresponding to an effective maximum in the appropriate profile when the determination means determines one appropriate profile, and sets the optimum sound speed as the optimum sound speed. Diagnostic device. The apparatus of claim 1.
The ultrasonic diagnostic, wherein the profile generation means generates a profile for each reference region by generating an approximate curve based on a plurality of evaluation values corresponding to the plurality of trial delay conditions. apparatus. The apparatus of claim 1.
An ultrasonic diagnostic apparatus comprising: means for displaying or recording information indicating an optimum sound speed calculated during the test operation during execution of the ultrasonic diagnosis during the normal operation.

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