JPH10328185A - Ultrasonic diagnostic system and ultrasonic wave transmitting/receiving method for diagnosis - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniform ultrasonic images by equalizing an angle and a signal level in the transmission of two scanning lines to be provided in one time of transmission. SOLUTION: A transmission delay data generating part 12 generates transmission delay data determining delay time for each vibrator at a probe 10 in order to form a transmission beam in the target transmission direction. On the other hand, both reception adder circuits 22a and 22b respectively output the angle of deviation between target and real reception directions to a correction value determining part 32 as the error of delay characteristics. The correction value determining part 32 determines the amount of correction in the target transmission direction required for forming the transmission beam at the center of two reception beams to be really formed. Based on this correction amount, a transmission delay data converting part 14 corrects the transmission delay data. While using the corrected data, the transmission beam is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an ultrasonic diagnostic apparatus,
In particular, the present invention relates to an ultrasonic diagnostic apparatus that performs two-way simultaneous reception in which two reception beams are formed for one transmission beam.

[0002]

2. Description of the Related Art An ultrasonic diagnostic apparatus that transmits an ultrasonic pulse to a subject, receives ultrasonic waves reflected in the subject, processes the received waves, and obtains information on the subject is well known. In the ultrasonic diagnostic apparatus, it is desired to increase the number of scanning lines in one frame or increase the number of frames (frame rate) obtained per unit time in order to improve the image quality of an ultrasonic image. In order to meet such a demand, it is effective to increase the number of ultrasonic beams formed per unit time. In order to increase the number of beams, an ultrasonic diagnostic apparatus that performs simultaneous two-way reception has been proposed.

FIG. 7 shows an ultrasonic beam (transmission beam and reception beam) formed when two-way simultaneous reception is performed in sector scanning. In FIG. 7, a transmission beam Tx is formed in a certain direction. Then, on both sides of the transmission beam Tx, two symmetric reception beams Rx1,
Rx2 is formed (actually, the angle formed by the transmission beam and the reception beam is about 1 degree, but is schematically shown in the figure; the same applies hereinafter). Therefore, for each transmission, the combined beams (scanning lines) X1 and X2 of the transmission and reception beams are 2
The book is obtained. As a result, the number of scanning lines in one frame is reduced to two.
It is possible to double the frame rate or double the frame rate.

As is well known, the direction of a transmission beam (hereinafter, referred to as
The transmission direction) can be controlled by a delay process that slightly shifts the timing of driving each ultrasonic vibration element (piezoelectric element) constituting the array transducer. The transmission direction is determined by the distribution of the delay time of each vibration element. Similarly, the direction of the reception beam (hereinafter referred to as reception direction) can be controlled by a delay process that slightly shifts the reception timing.
When performing two-way simultaneous reception, two reception delay addition circuits are generally provided to simultaneously form two reception beams.

[0005]

In an ultrasonic diagnostic apparatus, there is a considerable difference between a direction in which a reception beam is to be formed and a direction in which a reception beam is actually formed. A typical cause of this shift is an error in the delay characteristics of the delay line provided in the delay addition circuit for reception. The delay line has, for example, a plurality of connected LC delay elements. Since the delay elements vary in performance, the set value of the delay time of the delay line differs from the actual delay time.

[0006] In a device that performs two-way simultaneous reception, there are two delay addition processing circuits, and in each delay addition circuit, a shift occurs between the target and the actual reception direction. Therefore, the two reception beams are not formed symmetrically with respect to the transmission beam, that is, the transmission beam is shifted from the center of the two reception beams. The angle θ1 between the left receiving beam Rx1 and the transmitting beam Tx and the angle θ2 between the right receiving beam Rx2 and the transmitting beam Tx are not actually equal as shown in FIG.

Here, the smaller the angle between the transmission beam and the reception beam, the higher the signal level of the combined beam and the higher the sensitivity. Assume that θ1> θ2 as shown in FIG. In this case, as shown in FIG. 9, the signal level of the right combined beam X2 is higher than that of the left combined beam X1. When such beam forming is repeatedly performed by electronic scanning, the signal level of the scanning line becomes 1
It fluctuates every other book, and does not become an equal angle signal. As a result, as shown in FIG. 10, a stripe pattern appears in the ultrasonic image obtained using the received signal, and a uniform ultrasonic image cannot be obtained, making it difficult to view the ultrasonic image.

[0008] In the sector scanning type ultrasonic diagnostic apparatus, the above-mentioned problem is remarkable. In the sector scanning method, since the delay time between the vibrating elements is increased as the scanning angle (the angle between the center direction of the probe and the transmission / reception direction) increases, the error of the delay characteristic of the delay addition circuit in a region where the scanning angle is large. Strongly appears.

Conventionally, in order to solve the above-mentioned problem, the sensitivity difference between two scanning lines has been reduced by setting the focus setting of the transmission beam and the reception beam to broad focus. However, in this case, the range in which the focus can be narrowed is restricted, and the sharpness (sharpness) of the ultrasonic image is affected. Further, if the focus setting is broad focus, the transmission power is reduced, so that the setting range of the opening angle between the transmission beam and the reception beam is restricted. These restrictions differ depending on the opening width of the probe used. Therefore, it is desired to prevent the occurrence of a stripe pattern in an ultrasonic image without employing broad focus.

As described above, in the conventional two-way simultaneous reception, since there are errors in the receiving directions of the two receiving beams, the two receiving beams are not formed symmetrically with respect to the transmitting beam. Therefore, a stripe pattern that makes the ultrasonic image non-uniform occurs. The error in the receiving direction is caused by an error in the delay characteristic of the delay addition circuit. The delay addition circuit has, for example, a structure including a plurality of connected delay elements, and an error in the delay characteristic is a variation in performance due to this structure. With such a structure, it is difficult to sufficiently improve the image quality by improving the accuracy and correction of the receiving direction. Further, if the beam focus setting is set to be broad, the sharpness of the image is adversely affected.

The present invention has been made in view of the above problems. An object of the present invention is to provide an ultrasonic diagnostic apparatus capable of equalizing an ultrasonic image by equalizing an angle with respect to transmission of two scanning lines obtained for one transmission and a signal level with a simple configuration in simultaneous two-way reception, and It is an object of the present invention to provide a diagnostic ultrasonic transmitting / receiving method.

[0012]

According to an ultrasonic diagnostic apparatus of the present invention, there is provided an array vibrator in which a plurality of ultrasonic vibrating elements are arranged, a transmission control unit for forming a transmitting beam by electronic scanning of the array vibrator, 2 symmetrical about each transmit beam
And a reception control unit having two reception delay addition circuits for forming the reception beams. As a feature of the present invention, in order to form a transmission beam in a target transmission direction, a transmission delay data generation unit that generates transmission delay data that defines a drive delay time for each of the ultrasonic transducers, Correction amount for obtaining a correction parameter indicating a correction amount in the target transmission direction required to form a transmission beam at the center of two actually formed reception beams based on an error in delay characteristics of the delay addition circuit for use. A deciding unit and a transmission delay data correction unit that corrects transmission delay data according to the correction parameter are included.

Each of the two delay addition circuits for simultaneous two-way reception has an error in delay characteristics. If the error of the delay characteristic is known, the direction in which the two reception beams are actually formed can be known. Here, as described above, it is difficult to finely adjust the reception direction, and it is not easy to make the two reception beams symmetric with respect to the transmission beam by correcting the reception direction. However, the transmission direction can generally be finely adjusted. In the transmission circuit, for example, when the drive timing of each ultrasonic vibration element indicated in the transmission delay data matches the count number of the control clock, a trigger signal for driving the vibration element is issued. As described above, the transmission circuit has a delay processing configuration different from that of the reception circuit, and allows fine control of the transmission direction.

Therefore, in the present invention, the transmission direction of the transmission beam is corrected. The shift between the target and the actual receiving direction can be determined from the delay characteristics of the delay adding circuit. Therefore, it is possible to know in which direction each of the two reception beams is actually formed.
Thereby, a line passing through the center of the two reception beams is known. A correction parameter indicating the amount of correction in the target transmission direction required to form a transmission beam in the direction of this line is obtained, transmission delay data is corrected according to this parameter, and transmission of ultrasonic waves is performed using the corrected delay data. Is performed. Therefore, the reception beam is formed symmetrically on both sides of the transmission beam, and the signal levels of the combined beam of the transmission beam and the reception beam are equal on the left side and the right side, and as a result,
The ultrasonic diagnostic image becomes uniform. The correction of the transmission delay data for correcting the transmission direction can be realized by a simple configuration such as a ROM storing a correction table.

As described above, according to the present invention, by correcting the transmission direction of the transmission beam, it is possible to prevent the occurrence of a stripe pattern in the ultrasonic image when two-way simultaneous reception is performed. The transmission direction is
It can be easily and finely corrected. The correction of the transmission direction can be realized with a simple configuration. There is no degradation in image quality as in the case of employing broad focus. Therefore, the image quality of the ultrasonic image can be improved with a simple configuration while taking advantage of the simultaneous reception in two directions.

Further, according to the diagnostic ultrasonic transmission / reception method of the present invention, a transmission beam is formed by electronic scanning of an array vibrator in which a plurality of ultrasonic vibrating elements are arrayed, and the transmission / reception beam is symmetrical about each transmission beam. A method of forming two reception beams, wherein a target transmission direction of a transmission beam is corrected based on an error between a target reception direction of the two reception beams and an actual reception direction to form two reception beams. A transmission beam is formed at the center of the reception beams of the book. For example, the correction amount of the transmission beam in the target transmission direction is determined based on the error of the delay characteristics of the two delay addition circuits forming one reception beam.

According to the present invention, the same effects as those of the above-described ultrasonic diagnostic apparatus can be obtained. In the present invention, the transmission delay data may be generated first, and then the transmission delay data may be subjected to an appropriate conversion process for the correction of the present invention. Alternatively, the determined target transmission direction may be corrected first, and transmission delay data may be generated based on the corrected target transmission direction. When generating the transmission delay data, correction of the target transmission direction can be taken into account. Thus, the correction of the target transmission direction may be performed at any stage of the transmission system.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention (hereinafter, referred to as embodiments) will be described below with reference to the drawings. FIG. 1 is a block diagram showing a sector scanning ultrasonic diagnostic apparatus according to the present embodiment. In the present apparatus, a B-mode image and a Doppler mode image (using autocorrelation, the direction of blood flow and the average velocity are represented by colors) are synthesized and displayed.

The probe 10 is provided with a plurality of ultrasonic vibration elements (hereinafter, referred to as vibration elements) arranged.
Ultrasonic waves are transmitted / received using the probe 10, and one transmission / reception forms one transmission beam and two reception beams on both sides thereof. The transmission and reception of ultrasonic waves are sequentially repeated while changing the direction, thereby performing sector scanning. Hereinafter, a direction in which a transmission beam is to be formed in one transmission / reception is called a target transmission direction, and a direction in which a reception beam is to be formed is called a target reception direction. Since simultaneous two-way reception is performed, there are two target reception directions for one transmission / reception.

The transmission delay data generation section 12 has a ROM, and generates transmission delay data (transmission focus delay data) that defines a delay time when the probe 10 is driven for each vibration element. A transmission beam is formed by a delay process for gradually shifting the driving time of the vibrating element. The direction in which the transmission beam is formed is determined by the distribution of the drive delay time. Therefore, transmission delay data is generated such that a transmission beam is formed in the target transmission direction. The transmission delay data is digital data of a plurality of bits for each transducer.

The transmission delay data generator 12 is connected to a transmission delay data converter 14 characteristic of the present invention. The transmission delay data conversion unit 14 receives an angle correction parameter from the correction value determination unit 32. The angle correction parameter indicates a correction amount in the target transmission direction. The transmission delay data converter 14 converts the transmission delay data so that a transmission beam is formed in a direction corrected using the correction amount. The transmission delay data converter 14 will be described later together with the correction value determiner 32.

The transmission delay data converter 14 is connected to the transmission trigger generator 16. Transmission trigger generator 1
6 receives a clock signal. The transmission trigger generator 16 counts the clock signal until the delay time indicated by the transmission delay data has elapsed. Then, when the delay time has elapsed, a transmission trigger signal for driving the vibrating element is generated and output. The generation of the transmission trigger signal is performed for each vibration element based on the drive delay time of each vibration element. As described above, in the transmission of the ultrasonic wave, control based on the clock signal is performed. Therefore, the transmission beam is accurately formed in the target transmission direction, and the error is small. Further, fine adjustment of the transmission direction can be easily performed by converting the transmission delay data.

The transmission trigger generator 16 includes a transmission driver 18
It is connected to the. The transmission driver 18 amplifies the transmission trigger and supplies it to the probe 10. The vibration element of the probe 10 emits an ultrasonic wave when driven by a transmission trigger. As described above, the transmission trigger is supplied at a timing shifted for each vibration element. As a result, the transmission beam Tx is formed in the direction corrected by the transmission delay data conversion unit 14.

As a configuration of a receiving system, a wave receiving amplifier 20 is connected to the probe 10. Each vibrating element of the probe 10 receives an ultrasonic wave and converts it into an electric signal. The receiving amplifier 20 amplifies the electric signal input from the probe 10.

The receiving amplifier 20 includes a first receiving and adding circuit 2
2a and the second receiving and adding circuit 22b are connected.
First and second reception delay data are input to the first and second reception addition circuits 22a and 22b from the first and second reception delay data generators 24a and 24b, respectively. First,
The second reception delay data is data that defines a delay time at the time of reception for each vibration element. The target reception directions of the first and second received delay data are symmetrical left and right about the transmission target direction. The target receiving directions of the first and second received delay data are referred to as a first target receiving direction and a second target receiving direction, respectively. A reception beam is formed by adding the reception signals for each vibrating element after slightly shifting the reception signals in time. The direction in which the reception beam is formed is determined by the distribution of the reception delay time. The first and second reception delay data are generated such that reception beams are formed in the first and second target reception directions, respectively.

Each of the receiving and adding circuits 22a and 22b has a plurality of LC type delay lines. Using this delay line, a delay indicated in the received delay data is given to the received signal for each vibrating element. The delay time is slightly shifted for each vibration element. The delayed received signals are added and output as an echo signal. Thus, the first reception beam Rx1 and the second reception beam Rx2 are formed in the first and second target reception directions, respectively.

However, the first receiving and adding circuit 22a uses a plurality of delay lines, and the delay lines have relatively large performance variations. Therefore, there is an error in the delay characteristic of the first reception adder circuit 22a, and a difference occurs between the delay time indicated in the received delay data and the actually realized delay time. As a result, a deviation occurs between the first target reception direction and the actual reception direction of the first reception beam Rx1. The first receiving and adding circuit 22a stores a deviation angle between the target and the actual receiving direction as a first delay device performance value indicating an error in the delay characteristic. The performance value of the first delay unit is measured at the time of manufacturing the first receiving and adding circuit 22a, and is stored in the circuit.

The same applies to the second reception and addition circuit 22b. The second reception and addition circuit 22b stores the second delay device performance value. The error of the delay characteristic usually differs for each circuit, and therefore, the first delay device performance value and the second delay device performance value also differ.

The first delay unit performance value and the second delay unit performance value are sent to the correction value determination unit 32. Correction value determination unit 32
Calculates the correction amount in the target transmission direction required to form a transmission beam at the center of the reception beam based on both input performance values, and transmits a correction parameter indicating the correction amount to the transmission delay data conversion unit 14. Output.

For example, in FIG. 2, dotted lines indicate a target transmission direction used by the transmission delay data generator 12 and a target reception direction used by the first and second reception delay data generators 24a and 24b. In the target reception direction and the direction in which the reception beams Rx1 and Rx2 are actually formed,
As shown, there are deviations of the angles Δθ1 and Δθ2, respectively. These Δθ1 and Δθ2 are input as a first delay device performance value and a second delay device performance value, respectively. In FIG. 2, Δα is a correction amount of a target transmission direction necessary for forming a transmission beam at the center of two reception beams. That is, the angle indicates how far the transmission beam is shifted so that the transmission beam is located at the center of the two reception beams. The correction amount Δα is obtained based on the delay performance values Δθ1 and Δθ2 (Δα = (Δθ1 + Δθ2) / 2). Then, a correction parameter indicating the correction amount Δα is output.

The correction value determining section 32 has a ROM,
The ROM stores the correction parameter determination table of FIG. 3 in advance. The first delay performance value, the second delay performance value, and the correction parameter are associated with each other in the correction parameter determination table. Correction value determination unit 32
Reads out the correction parameters corresponding to the input delay performance values and outputs the correction parameters to the transmission delay data conversion unit 14. Further, the correction value determination unit 32 can be realized by a configuration having an adder.

The transmission delay data conversion section 14 has a ROM, in which the conversion table of FIG. 4 is stored in advance. In FIG. 4, the horizontal axis represents the input value of the delay time, and the delay time input value is included in the transmission delay data input from the transmission delay data generation unit 12 to the transmission delay data conversion unit 14. The delay time is a plurality of bits of digital data for each vibration element as described above. The vertical axis is the converted delay time data output from the transmission delay data converter 14 to the transmission trigger generator 16.

In the conversion table of FIG. 4, a plurality of conversion characteristic lines having slightly different inclinations are set. One of the characteristic lines is selected, and conversion is performed using the selected line. The slope of the line m0 in the drawing is 1, and when the line m0 is selected, a delay time having the same value as the input value is output. The slope of the line m1 is slightly larger than 1,
When the line m1 is selected, the input value is gradually converted to a larger value and output. The opposite is true when line m2 is selected. By changing the delay time little by little according to the conversion characteristic line, the transmission direction of the transmission beam can be shifted from the original target transmission direction.

In the transmission delay data conversion section 14, the correction parameter is associated with the conversion characteristic line to be selected based on the angle change of the transmission direction when each conversion characteristic line is used. Then, a conversion characteristic line corresponding to the input correction parameter is selected. Accordingly, the transmission direction of the transmission beam formed using the output data of the transmission delay data conversion unit 14 is a direction obtained by correcting the initial target transmission direction by the correction amount indicated by the correction parameter. In the table of FIG. 4, the conversion characteristic line is a straight line. In the case of the angle correction intended in the present embodiment, a sufficient degree of correction is possible by the setting in FIG.

On the other hand, the first reception and addition circuit 22a and the second reception and addition circuit 22b are connected to a B-mode compression detection circuit 26 and an autocorrelation type Doppler processing unit 27 having the same configuration as the conventional one. Both the B-mode compression detection circuit 26 and the autocorrelation Doppler processing unit 27 are connected to the image processing circuit 28,
The display 30 is connected to the image processing circuit 28. The echo signals generated by the delay addition processing in the first reception addition circuit 22a and the second reception addition circuit 22b are output to the B-mode compression detection circuit 26 and the autocorrelation Doppler processing unit 27. The B-mode compression detection circuit 26 extracts information representing the shape of the subject based on the received signal by processing such as detection. The autocorrelation type Doppler processing unit 27 performs orthogonal detection processing, autocorrelation processing, and the like on the echo signal, and extracts information on the direction of blood flow and the average velocity in each part of the subject.

The image processing circuit 28 generates a B-mode tomographic image of the subject based on the input information from the B-mode compression detection circuit 26. The blood flow information input from the autocorrelation type Doppler processing unit 27 is colored to indicate the direction of the blood flow and the average velocity. The image processing circuit 28 superimposes the colored information on the B-mode tomographic image. As a result, 2
A tomographic image representing the direction and the flow velocity of the blood flow in each part together with the dimensional shape is generated. The display 30 has a CRT or the like, and displays the generated tomographic image. In this embodiment, two-way simultaneous reception is performed, and two combined beams (transmission beam + reception beam) are formed for each transmission / reception. Therefore, if the number of scanning lines in one frame is the same as usual, the frame rate can be doubled. If the frame rate is the same as normal, the number of scanning lines in one frame can be doubled. Therefore, the image quality of the ultrasonic image displayed on the display 30 can be improved.

Next, the operation of the above ultrasonic diagnostic apparatus will be described. The ultrasonic diagnostic apparatus is controlled by a higher-level control unit (not shown) to sequentially change the scan angle to form an ultrasonic beam, thereby performing a sector scan. Then, an echo image for one frame is generated by combining echo data on a large number of scanning lines obtained from a predetermined angle range. Here, the transmission and reception of ultrasonic waves when the center direction of the probe 10 and the target transmission direction make an angle α will be described with reference to FIG.

First, the transmission delay data generation unit 12
Transmission delay data is generated such that a transmission beam is formed in a target transmission direction indicated by a chain line Tx0 in FIG.
A one-dot chain line curve f0 shown in FIG. 5 schematically shows the distribution of the delay time (delay amount) for each vibration element in the transmission focus delay data generated here.
The transmission delay data is transmitted by the transmission delay data converter 14.
Output to

The transmission delay data converter 14 receives the correction parameters from the correction value determiner 32. The correction parameter is determined by the correction value determination unit 32. The correction value determining unit 32 includes a first reception adding circuit 2
A correction parameter is determined using the correction parameter determination table of FIG. 3 based on the first delay unit performance value and the second delay unit performance value input from the 2a and the second reception addition circuit 22b, respectively. The correction parameters determined here are:
This corresponds to the correction amount Δα described above.

The transmission delay data converter 14 selects a change characteristic line corresponding to the input correction parameter from the conversion table shown in FIG. The transmission delay data input from the transmission delay data generation unit 12 is converted using the selected line. For example, line m in FIG.
Assume that 2 has been selected. The input transmission delay data includes a delay time for each vibration element. The input value of the delay time of each vibration element is converted so as to be slightly smaller. As a result, the distribution of the delay amount of the transmission delay data is as shown by the solid line curve f1 in FIG. The converted transmission delay data is used as the transmission trigger generator 1
6 is output.

The transmission trigger generator 16 generates a transmission trigger based on the clock signal and the transmission delay data, and outputs the transmission trigger to the transmission driver 18. The transmission driver 18 amplifies the transmission trigger and outputs it to the probe 10. This allows
A transmission trigger is supplied to each vibration element at a timing corresponding to a delay time of the vibration element. The vibration element emits an ultrasonic wave when a transmission trigger is supplied.

Thus, the transmission beam Tx is formed. As a result of the conversion of the transmission delay data by the transmission delay data conversion unit 14, the transmission direction of the transmission beam Tx is a direction obtained by correcting the initial transmission direction applied by the transmission delay data generation unit 12 by the correction angle Δα.

The transmitted ultrasonic wave is reflected inside the subject,
It returns to the probe 10. Each vibrating element of the probe 10
The received ultrasonic wave is converted into an electric signal and output to the wave receiving amplifier 20. The receiving amplifier 20 amplifies the received signal and
The signal is output to the reception addition circuit 22a and the second reception addition circuit 22b.

The first reception addition circuit 22a performs a delay addition process of the reception signal based on the first reception delay data sent from the first reception delay data generation section 24a. Thereby, the reception beam Rx1 is formed. Due to the error in the delay characteristic of the first reception addition circuit 22a, the reception beam R
The receiving direction of x1 is shifted from the original target receiving direction (not shown). Similarly, the second receiving and adding circuit 22 b
The delay addition processing of the reception signal is performed based on the second reception delay data sent from the reception delay data generation unit 24b. Thereby, the reception beam Rx2 is formed. The receiving direction of the receiving beam Rx2 also deviates from the target receiving direction.

Therefore, assuming that the transmission delay data generated by the transmission delay data generator 10 is used as it is to form the transmission beam Tx0, the reception beams Rx1 and Rx2 are not bilaterally symmetric on both sides of the transmission beam. Therefore, as shown in FIG. 9 described above, the signal levels of the two combined beams X1 and X2 are different.

However, in the present embodiment, the transmission beam Tx is formed at the center of the two reception beams Rx1 and Rx2 by correcting the transmission delay data. As a result, as shown in FIG. 6, the combined beam X1 and the combined beam X
2 are almost equal.

The echo signals after the addition processing in the first reception addition circuit 22a and the second reception addition circuit 22b are output to the B-mode compression detection circuit 26 and the autocorrelation type Doppler processing unit 27. In the B-mode compression detection circuit 26, information indicating the shape of the subject is obtained. Further, the autocorrelation type Doppler processing unit 27 obtains the direction of blood flow and the average velocity.
These pieces of information are output to the image processing circuit 28. In addition,
The processing in the B-mode compression detection circuit 26 includes the echo signal from the first reception addition circuit 22a and the second reception addition circuit 22a.
This is performed for each of the echo signals from b. The same applies to the processing in the autocorrelation type Doppler processing unit 27.

The image processing circuit 28 combines the input data for all the scanning lines in the sector scanning range to generate an ultrasonic image for one frame. B-mode compression detection circuit 26
A B-mode tomographic image representing the two-dimensional shape of the subject is generated based on the input information from. The blood flow information input from the autocorrelation type Doppler processing unit 27 is colored so as to indicate the blood flow direction and the average velocity, and the colored information is superimposed on the B-mode tomographic image. As a result, an ultrasonic image representing the direction and flow velocity of the blood flow in each part together with the two-dimensional shape of the subject is generated. This ultrasonic image is displayed on the display 30. As described above, in the present embodiment, 2 obtained by one transmission / reception is used.
The signal levels of the scanning lines are made uniform. Therefore, the signal level of the scanning line does not fluctuate every other line unlike the related art. Thus, the occurrence of a stripe pattern in the ultrasonic image is avoided, and a uniform and easy-to-view ultrasonic image is obtained.

The preferred embodiment of the present invention has been described above. In the present embodiment, the present invention is applied to a sector scanning type ultrasonic diagnostic apparatus. On the other hand, the present invention can be similarly applied to devices other than the sector scanning system, and devices of the linear scanning system and the convex scanning system.

In a preferred modification of the present embodiment, the correction amount of the target transmission direction may be changed for each probe. Conditions such as the size of the aperture and the degree of directivity are different for each probe. By correcting the transmission direction according to the difference between the conditions, it is possible to further improve the image quality of the ultrasonic image. Therefore, the correction parameter determination table of FIG. 3 is created for each probe, and the plurality of tables are stored in the correction value determination unit 32. Further, a ROM for storing probe parameters for identifying the probe is provided. The correction value determination unit 32 determines a correction parameter using a table corresponding to the probe parameters sent from the ROM.

Further, as a modification, the correction amount in the target transmission direction may be changed for each scanning angle. As the scanning angle increases, it is necessary to increase the delay time of each vibration element. As is well known, the control of the delay time is, for example,
This is realized by changing the connection relationship between the line to which the received signal is input and the delay line by operating a switch. A multiplexer or the like is provided for this connection switching. Therefore, the manner in which the delay circuit is used differs depending on the scanning angle. As a result, the deviation between the target and the actual receiving direction
It varies slightly depending on the scanning angle. Taking this point into account,
At the full scan angle, the transmit delay data is corrected so that the transmit beam is more accurately formed at the center of both receive beams.

For example, the correction parameter determination table of the correction value determination section 32 is modified. Information indicating the scanning angle is input to the correction value determination unit 32 from a higher-level control unit (not shown).
The correction value determination unit 32 determines a correction parameter according to the first delay unit performance value, the second delay unit performance value, and the scan angle, and outputs the correction parameter to the transmission delay data conversion unit 14.

For example, the transmission delay data converter 1
4 is transformed. Information indicating the scanning angle is input to the transmission delay data conversion unit 14 from a higher-level control unit (not shown). The transmission delay data conversion unit 14 selects a characteristic line to be used for conversion according to the correction parameter and the scan angle. For different scan angles, different lines are selected from the table of FIG. Thus, the correction amount in the transmission direction can be changed according to the scanning angle.

[0054]

According to the present invention, it is possible to equalize the signal levels of the scanning lines in the two-way simultaneous reception with a simple configuration without taking measures to reduce the image quality such as broad focus, etc. A sound image is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an overall configuration of an embodiment of the present invention.

FIG. 2 is a diagram illustrating a method of obtaining a correction amount in a target transmission direction.

FIG. 3 is a diagram illustrating a correction parameter determination table for obtaining a correction parameter indicating a correction amount in a target transmission direction.

FIG. 4 is a diagram showing a conversion table for converting transmission delay data according to a correction parameter.

FIG. 5 is a diagram illustrating transmission delay data and an ultrasonic beam generated by the diagnostic device of FIG. 1;

6 is a diagram schematically showing a signal level of an ultrasonic beam formed by the diagnostic device of FIG.

FIG. 7 is a diagram illustrating the principle of two-way simultaneous reception.

FIG. 8 is a diagram showing an ultrasonic beam formed when an actual receiving direction deviates from a target in two-way simultaneous reception.

9 is a diagram schematically showing signal levels of two combined beams in the situation of FIG.

10 is a diagram schematically showing a stripe pattern generated in an ultrasonic image due to a difference in signal level in FIG. 9;

[Explanation of symbols]

10 probe, 12 transmission delay data generator, 14
Transmission delay data conversion unit, 16 transmission trigger generation unit, 18 transmission driver, 20 reception amplifier, 22a
First receiving and adding circuit, 22b Second receiving and adding circuit, 24a
1st received delay data generation unit, 24b 2nd received delay data generation unit, 26 B-mode compression detection circuit, 2
7 Autocorrelation Doppler processing unit, 28 image processing circuit, 3
0 indicator, 32 correction value determination unit.

Claims (3)

[Claims] 1. An array transducer in which a plurality of ultrasonic transducers are arranged, a transmission control unit for forming a transmission beam by electronic scanning of the array transducer, and two reception devices symmetrical about each transmission beam. And a reception control unit having two reception delay addition circuits for forming beams. In the ultrasonic diagnostic apparatus, in order to form a transmission beam in a target transmission direction, a drive delay time for each of the ultrasonic vibration elements is determined. A transmission delay data generating unit for generating the transmission delay data, and forming a transmission beam at the center of two actually formed reception beams based on an error in delay characteristics of the two reception delay addition circuits. A correction amount determining unit for obtaining a correction parameter indicating a correction amount in the target transmission direction required for transmission delay data for correcting transmission delay data according to the correction parameter An ultrasonic diagnostic apparatus, comprising: 2. A diagnostic ultrasonic diagnostic device that forms a transmission beam by electronic scanning of an array transducer in which a plurality of ultrasonic transducers are arranged, and forms two reception beams that are bilaterally symmetric about each transmission beam. In the sound wave transmitting / receiving method, a target transmission direction of a transmission beam is corrected based on an error between a target reception direction of the two reception beams and an actual reception direction, and transmitted to the center of the two reception beams actually formed. A diagnostic ultrasonic transmission / reception method, comprising forming a beam. 3. The method according to claim 2, wherein a correction amount of a transmission beam in a target transmission direction is determined based on an error in delay characteristics of two delay addition circuits each forming one reception beam. A diagnostic ultrasonic transmission / reception method, characterized by the following.