JPH02182245A - Transmitting-receiving apparatus of ultrasonic diagnostic apparatus - Google Patents

Abstract

PURPOSE:To reduce cost by minimizing the number of transmitting-receiving circuits or delay elements by reducing the number of the ultrasonic vibrators connected to the transmitting-receiving circuit blocks connected to the delay elements in the vicinity of both terminals of a theoretical delay pattern as compared with the number of those connected in the vicinity of the central part of the theoretical delay pattern. CONSTITUTION:The transmitting-receiving circuit blocks 402-404 constituting a transmitting-receiving circuit 40 are connected to the respective delay elements 301-303 constituting a delay circuit 30 and an ultrasonic vibrator block 601 composed of one ultrasonic vibrator is connected to the transmitting-receiving circuit block 401 and an ultrasonic vibrator block 602 composed of two ultrasonic vibrators is connected to the transmitting-receiving circuit block 403 and an ultrasonic vibrator block 603 consisting of three ultrasonic vibrators is connected to the transmitting-receiving circuit block 403 and an ultrasonic vibrator block 604 consisting of five ultrasonic vibrators is connected to the transmitting-receiving circuit block 404. Nine ultrasonic vibrators in total are connected to the transmitting-receiving circuit 40. An ultrasonic vibrator selection circuit 50 is possible in switching operation with respect to all of the ultrasonic vibrators constituting an ultrasonic probe 6.

Description

Detailed Description of the Invention (Industrial Field of Application) This invention converges and scans ultrasound through electrical control, and uses the reflection of the ultrasound inside the human body to create a cross-sectional image of a subject. The present invention relates to a transmitting/receiving device of an ultrasonic diagnostic apparatus for performing medical diagnosis by visualizing a surface.

[Conventional technology]

Ultrasonic diagnostic equipment emits ultrasonic waves into the body of a human subject and receives the ultrasonic waves that are reflected from the interfaces of organs within the body, which is repeated by changing the position. It is used to obtain tomographic images of the subject.

In order to obtain two-dimensional tomographic images, ultrasound diagnostic equipment transmits ultrasound that focuses at several different positions in the depth direction of the human body, obtains image data in the depth direction for each focus, and A single piece of image data in the depth direction is obtained by appropriately combining the data. Furthermore, one tomographic image can be obtained by scanning the surface direction of the human body perpendicular to the depth direction at predetermined intervals to obtain two-dimensional image data. Creation of such a tomographic image 1
By performing this several dozen times per second and displaying it on a monitor television as a display device, images can be obtained that are synchronized with changes inside the human body and movements of the ultrasound probe as an ultrasound transmitter/receiver by the operator. In order to obtain such a tomographic image, high-speed processing is required, so all processing is performed using electronic circuits.

FIG. 3 is a block diagram of the transmitting and receiving device of the ultrasonic diagnostic apparatus. In this figure, the operation during transmission is as follows.

The pulse generation circuit 1 periodically generates pulses based on commands from a control circuit (not shown) that controls the entire ultrasonic diagnostic apparatus. This pulse signal is input to the delay circuit 3. This delay circuit 3 is composed of a plurality of delay elements having different delay amounts, as will be described later.The above-mentioned pulse signals are inputted in parallel to these delay elements, and the pulses delayed by different delay amounts for each delay element are transmitted to each delay element. output every time.

These pulse signals are input to the transmitter/receiver circuit 4, inputted to a plurality of transmitter circuit blocks provided in one-to-one correspondence with the delay elements constituting the transmitter/receiver circuit, and delayed for each transmitter circuit block. A transmission signal of a predetermined frequency is output according to the pulse signal. An ultrasonic transducer selection circuit 5 is provided in the ultrasonic probe 6 to select an ultrasonic transducer to which this transmission signal is input. The number of ultrasonic transducers excited in one transmission is a small portion of the ultrasonic transducers that constitute the ultrasonic probe 6. Which ultrasonic transducer to select is determined by the scanning position, and this is also controlled by the aforementioned control circuit.

The ultrasonic transducer is excited by the transmission signal and generates ultrasonic waves. The ultrasound probe 6 is in contact with the subject, and ultrasonic signals are transmitted into the subject. The transmitted ultrasonic waves are reflected within the subject, and the reflected waves are captured by the ultrasonic probe 6. The ultrasonic transducer constituting the ultrasonic probe 6 enters the receiving state after transmitting an ultrasonic signal as described above, receives the reflected wave, and converts it into an electrical signal as a received signal. The reception operation after the reception signal is received is as follows.

The received signal converted into an electric signal by the ultrasound probe 6 is input to the transmission/reception circuit block of the transmission/reception circuit 4 via the ultrasound transducer selection circuit 5. Ultrasonic transducer selection circuit 5
maintains the same connection relationship as at the time of transmission. The received signal is amplified by a receiving circuit block serving as a preamplifier that constitutes the transmitting/receiving circuit 4, passes through the delay circuit 3, and is given a delay based on a different amount of delay for each delay element, thereby adjusting the phase. The signals are combined into one electrical signal and input to the received signal processing circuit 8.

The received signal processing circuit 8 performs analog signal processing such as filter processing and detection processing, and then converts it into a digital signal by an A/D conversion circuit (not shown) and stores it in an image storage device of a digital scan controller abbreviated as DSC. It will be stored. The image data in the image storage device is retrieved by a predetermined method and visualized on a monitor television. Approximately 30 pieces of two-dimensional image data as tomographic images are generated per second, and the two-dimensional image data stored in the image storage device mentioned above is sequentially rewritten, so the image displayed on the monitor TV does not match the subject or ultrasound probe. The resulting moving image follows the child's movements, which is a major advantage of ultrasound diagnostic equipment.

The delay element selection circuit 2 instructs which delay element group to use for each different delay pattern.In recent ultrasound diagnostic equipment, multiple focal points are set for one scanning position. to obtain image data for each focal position, combine these to obtain one-dimensional image data on one scanning line, and move the scanning line sequentially to obtain two-dimensional image data as described above. A method is adopted in which two-dimensional image data is stored in an image data storage device within the DSC. Since the combination of delay elements differs depending on the focus position, the delay element selection circuit 2 selects and specifies the delay element group corresponding to the target focus position from among the plurality of delay element groups.

FIG. 4 is a diagram for explaining delay patterns. A focal point II is set at a position within the subject by a distance DF from the subject surface 12 to which the ultrasonic probe 6 is applied. The width dimension LF of the delay pattern 10 is determined from the number of ultrasonic transducers that transmit simultaneously and the size of one ultrasonic transducer. The theoretical delay pattern 10 is an arc of width formed on the surface 12 of the subject with the center position at the focal point if l l. Also, 1
3 represents a scanning line.

Assume that ultrasonic transducers are arranged on the arc of the delay pattern 10 so that the direction of emitting ultrasonic waves is parallel to the scanning line 13, and ultrasonic waves of the same phase are emitted.

It is assumed that the propagation speed of the ultrasonic waves on the paper surface is all constant. Since the distance between all the ultrasonic transducers on the theoretical delay pattern 10 and the focal point W11 is the same, all the phases of the ultrasonic waves emitted from each ultrasonic transducer are aligned at the focal point 11, and the ultrasonic waves are The intensity of the sound waves increases.

The actual ultrasonic probe 6 has ultrasonic transducers arranged on the surface 12 of the subject, and instead, for the ultrasonic transducer located at point P in the figure, the distance δ between the theoretical delay pattern 10 and point P is By giving the transmission signal a delay amount corresponding to the propagation time of the ultrasonic wave, the equivalent ε is made to exhibit the same effect as if the ultrasonic transducers were arranged on the theoretical delay pattern 10.

FIG. 5 is a diagram showing the relationship between the delay amount of the delay element and the delay pattern. This figure shows the left half of the delay pattern, and the actual delay pattern has a right half that is line-symmetrical to the one shown. The theoretical delay pattern 10 shown as a circular arc is theoretically determined as described above. What is shown in a step-like manner is an actual delay pattern 100 that is an actual delay pattern when delayed by a delay amount corresponding to each ultrasonic transducer having a finite width.

In this figure, the number of ultrasonic transducers in the left half is 15, and three ultrasonic transducers are connected to one delay element. Therefore, including the right half (not shown), the number of ultrasonic transducers that simultaneously emit ultrasonic waves is 30, and the number of delay elements is 10. These numbers are for illustration purposes only.
The actual value is slightly larger than this. In fact, the delay pattern 100 consists of steps with five different delay amounts, and if the steps are numbered 101, 102, 103, 104, and 1.05 from the smallest, the delay steps 101 to 105 The respective delay amounts are determined so that the shape is closest to the theoretical delay pattern IO. When actually manufacturing an ultrasound transducer, a computer numerically simulates the phenomenon of ultrasound transmission to determine the amount of delay that will yield the best tomographic image.

FIG. 6 is a block circuit diagram conceptually showing the connection relationship of the respective blocks of the delay circuit 3, the transmitting/receiving circuit 4, the ultrasonic transducer selection circuit 5, and the ultrasonic probe 6. In this figure, the transmitting/receiving circuit 4 is composed of seven transmitting/receiving blocks 41 to 47, and correspondingly, the delay circuit 3 has five delay elements 32 to 47 with the delay elements connected to the transmitting/receiving circuit blocks 41 and 47 omitted. It consists of 36 pieces.

The delay amounts of the delay elements on both sides are omitted because the delay amounts of the transmitting/receiving circuit blocks 41 and 47 are subtracted from the delay amounts of all delay elements.

The three ultrasonic transducers 60 that constitute the ultrasonic probe 6 are one
They constitute a set of ultrasonic transducer blocks 61 to 67. Although the ultrasonic transducer selection circuit 5 is shown as being composed of switches 51 to 57, it is actually constructed not as a mechanical switch but as an electronic circuit using semiconductor elements. Also, check if all the ultrasonic transducer blocks constituting the ultrasonic transducer 6 are connected to any of the seven transmitting/receiving circuits 41 to 47.
Since only one ultrasonic transducer block is connected, the number of switches required is seven for one ultrasonic transducer block. In an actual ultrasound diagnostic device, the number of transmitter/receiver circuit blocks is 30.
Since the number of ultrasonic transducer blocks is about 120, the ultrasonic transducer selection circuit 5 is composed of a group of switches arranged in a 30×120 matrix.

As mentioned above, in an actual ultrasonic diagnostic apparatus, the number of ultrasonic transducer blocks constituting the ultrasonic probe 6 is 120, so the number of ultrasonic transducers is about 360, which is three times this number. The reason why the number of parts is shown in small numbers in FIGS. 5 and 6 is simply for the purpose of simplifying the illustration. The number of ultrasonic transducer blocks is approximately 120, while the number of ultrasonic transducer blocks that simultaneously emit ultrasonic waves is approximately 30, so the total number of ultrasonic transducers 60 that are excited simultaneously is approximately 120. 1/4 of the number of sound wave oscillators
That's about it. By shifting the positions of the ultrasonic transducer blocks that simultaneously emit ultrasonic waves by one ultrasonic transducer block, the positions of the scanning lines can be sequentially shifted.

As shown in FIG. 5, since the number of ultrasonic transducers that simultaneously transmit ultrasonic waves is limited, the actual delay pattern is 10.
0 changes discontinuously in a step-like manner, resulting in an overall shape close to an arc shape. Since the delay pattern has a discontinuous shape in this way, there is a phenomenon in which regions where the intensity of the ultrasonic waves is high are generated on the left and right sides of the focal position, and these regions are called grating lobes. As described above, in the array type ultrasound probe in which ultrasound transducers are arranged, the grating lobes create a virtual image in the tomographic image, which causes misdiagnosis in ultrasound diagnosis.

The position where the grating lobe is generated is the surface 12 of the object to be examined.
The angle formed with the scanning line 13 is roughly expressed by the following equation, with the origin being the intersection of the scanning line 13 and the scanning line 13.

θ, = sin - + (λ/nd) where, λ; Wavelength of ultrasound n; Number of ultrasound transducers in the ultrasound transducer block d; Width dimension of ultrasound vibration This formula is This equation relates to the grating lobe that occurs when the ultrasonic waves are arranged linearly on the object surface 91 and emit ultrasonic waves of the same phase. Although it is different, there is no problem in using it for qualitative understanding.

[Problem to be solved by the invention]

In order to prevent a virtual image due to the grating lobe from occurring in the tomographic image, it is sufficient to satisfy the condition that the angle θ6 is greater than 90 degrees, and this angle θ. The smaller the value, the greater the intensity of the grating lobe, and therefore the stronger the virtual image will be displayed. Assuming that the frequency of the ultrasound is 3.5 MHz, the width dimension d of the ultrasound transducer is 0-35 mm, and the number n of ultrasound transducers constituting the ultrasound transducer block is 3, the ultrasound inside the subject Considering that the propagation velocity V of
．． 4. The angle θ6 is approximately 24 degrees, which means that a virtual image due to the grating lobe may occur in the tomographic image. By the way, if n is 1, the value in parentheses is 1.
．． 2, which satisfies the condition that grating lobes do not occur.

In order to prevent the generation of grating lobes, it would be sufficient to provide a transmitter/receiver circuit and a delay element for each ultrasonic transducer, but this would increase the number of these circuits and increase the price of the ultrasonic diagnostic equipment. There is a problem with the increase in

An object of the present invention is to provide a low-cost ultrasonic diagnostic apparatus that minimizes the number of transmitting/receiving circuits and delay elements while maintaining the quality of tomographic images at a predetermined level.

[Means to solve the problem]

In order to solve the above problems, according to the present invention, the focus position is set in the depth direction of the subject, the ultrasound is transmitted, the reflected waves are received, and the primary beam on one scanning line in the depth direction is transmitted. Transmission of ultrasonic pulses by an ultrasonic diagnostic apparatus that obtains original tomographic image data, obtains two-dimensional tomographic image data by electronically moving in a scanning direction perpendicular to the scanning line, and visualizes this image data. It is a transmitting/receiving device that also functions as a receiver, and it contacts the subject and transmits an ultrasonic pulse into the subject using an electrical signal as an input signal as an input signal, and also receives a reflected wave and transmits an electrical signal as a received signal. An ultrasonic probe comprising a plurality of ultrasonic transducers that output signals arranged in the scanning direction, and a delay amount determined from an arc-shaped theoretical delay pattern corresponding to the focal position for each ultrasonic transducer. A transmitting/receiving device comprising: a delay circuit including a plurality of delay elements for providing a transmitted signal and the received signal; and a transmitting/receiving circuit block that outputs the transmitted signal and amplifies the received signal, corresponding to each of the delay elements. In a transmitting/receiving device of an ultrasound diagnostic apparatus, the transmitting/receiving device of an ultrasound diagnostic apparatus includes a circuit and an ultrasound transducer selection circuit that changes the position of the scanning line by changing the connection relationship between the ultrasound transducer and the transmitting/receiving circuit block. The number of ultrasonic transducers connected to the transmitting/receiving circuit blocks connected to the delay elements located near both ends of the pattern is the theoretical number of the ultrasound transducers connected to the transmitting/receiving circuit blocks connected to the delay elements located near the center of the delay pattern. The number shall be smaller than that.

[Effect]

In the configuration of this invention, instead of keeping the number of ultrasonic transducers connected to one delay element constant, the number of ultrasonic transducers connected to delay elements at large slope positions at both ends of the theoretical delay pattern is The number of ultrasonic transducers is reduced, and instead, a large number of ultrasonic transducers are connected to delay elements located at a central portion with a small inclination. The angular position of the grating lobe is determined by the width of the steps in the actual step-like delay pattern.
Since the intensity is determined by the steps of the stairs, the grating lobes can be created by reducing the width of the stairs by reducing the number of ultrasonic transducers for each delay element at both ends of the arc with a large slope in the theoretical delay pattern. The generated angle is increased to prevent the formation of a virtual image, and the central portion of the arc with a small inclination is connected to one delay element. Increase the number of ultrasonic transducers and reduce the number of transmitting/receiving circuits and delay elements. Since the change in delay amount is small in the center of the arc,
Even if the number of ultrasonic transducers with the same amount of delay is large, the intensity of the grating lobe is small, so a virtual image with enough intensity to cause a problem will not occur in the tomographic image.

〔Example〕

The present invention will be explained below based on examples. FIG. 1 shows a delay circuit 30, a transmitter/receiver circuit 40, and an ultrasonic transducer selection circuit 5.
2 is a block circuit diagram showing the connection relationship between the ultrasonic probe 0 and the ultrasonic probe 6. FIG. In this figure, the lower half is omitted and only the upper half is shown. Transmitting/receiving circuit blocks 402 to 404 constituting the transmitting/receiving circuit 40 are connected to delay elements 301 to 303 constituting the delay circuit 30, respectively. The transmitter/receiver circuit block 402 includes an ultrasonic transducer block 60 consisting of two ultrasonic transducers.
2, an ultrasonic transducer block 603 consisting of three ultrasonic transducers is connected to the transmitting/receiving circuit block 403, and an ultrasonic transducer block 604 consisting of five ultrasonic transducers is connected to the transmitting/receiving circuit block 404. There is. The ultrasonic transducers connected to the transmitting/receiving circuit block 404 include four ultrasonic transducers not shown in the figure and omitted in the lower half, for a total of nine ultrasonic transducers. The numbers of delay elements 301 to 303, transmitting/receiving circuit blocks 401 to 404, and the number of ultrasound transducers 60 connected to each transmitting/receiving circuit block are hypothetical, and may not be actually employed in the ultrasound diagnostic apparatus to which this invention is applied. It is not a numerical value. These values are determined by the numerical simulation described above and by considering the quality of the tomographic image taking into account the occurrence of grating lobes, and by selecting the minimum delay element and transmitting/receiving circuit block that can obtain acceptable image quality. A delay element group having a number and an optimal delay amount corresponding to this number is determined. Furthermore, when determining acceptable image quality, a comprehensive judgment is made that also takes into consideration the prices of delay elements, transmitting/receiving circuit blocks, and the like.

The ultrasonic transducer selection circuit 50 needs to be able to perform a switching operation on all the ultrasonic transducers 60 that constitute the ultrasonic probe 6. That is, one ultrasonic transducer is sometimes connected to the transmitting/receiving circuit block 401 and forming the ultrasonic transducer block 601 with one ultrasonic transducer; Ultrasonic transducer block 6 consisting of two ultrasonic transducers
This is because it may be one of 04. Therefore, three times as many switching elements are required as compared to the conventional technique shown in FIG. 6, in which three ultrasonic transducers are connected to a transmitter/receiver circuit block as one ultrasonic transducer block. However, if you adopt a configuration in which the number of ultrasonic transducers connected to the transmitting/receiving circuit block is a multiple of 2 and two ultrasonic transducers become one ultrasonic transducer block, the number of switch elements can be 1.5 times. It turns out. Furthermore, in a conventional high-frequency ultrasonic diagnostic apparatus in which a set of delay elements and a transmitting/receiving circuit block are associated with one ultrasonic transducer, in applying the present invention, the switching element in the ultrasonic transducer selection circuit 50 is No increase occurs.

Since the transmitting/receiving circuit block 401 only excites one ultrasonic transducer, its output is sufficient for one ultrasonic transducer, the transmitting/receiving circuit block 402 has an output for two, and the transmitting/receiving circuit block 403 has an output for three. It becomes necessary. Similarly, the transmitter/receiver circuit block 404 requires nine outputs. In the same way, delay elements 301 to 303 having different allowable powers are prepared.

FIG. 2 is a diagram showing a delay pattern in an embodiment of the invention. In this figure, an actual delay pattern 110 is composed of seven delay steps 111 to 117 having different delay amounts with respect to the theoretical delay pattern IO. In FIG. 1, this value is set to 4, but this value is also simply illustrated for ease of drawing and visual recognition, and the difference between FIG. 1 and FIG. 2 has no meaning.

The delay amount stairs 11L112, 113 are each composed of one ultrasonic transducer, and the delay amount stairs 114, 115
, the delay amount staircase 116 consists of three ultrasonic transducers, and the delay amount staircase 117 consists of five ultrasonic transducers.

Since the slope of the theoretical delay pattern 10 is large at the positions of the delay steps 111, 112, and 113, the number of ultrasonic transducers constituting the delay steps at this portion is reduced to determine the angle θ at which the grating lobe is generated. The central delay step 117, where the slope of the theoretical delay pattern 10 becomes gentle, is made larger to prevent a virtual image from appearing in the tomographic image, and the delay step 117 in the center is made up of a large number of ultrasonic transducers to reduce the number of delay elements and transmitting/receiving circuits. is decreasing. The delay steps 114 to 116 are composed of an appropriate number of ultrasonic transducers between the delay step 11L112113 and the delay step 117. As mentioned above, the delay amount and the number of ultrasonic transducers that make up each of these delay steps are determined by numerical simulation, and the configuration shown in this figure shows the optimal configuration in a strict sense. It's not a thing. The conditions for determining the optimal configuration are the width dimension of one ultrasonic transducer, the frequency of the ultrasonic wave,
There are the number of delay elements, the degree of acceptable tomographic image quality, etc., and the optimum actual delay pattern 110 can only be set after these are set.

〔Effect of the invention〕

As described above, this invention reduces the number of ultrasonic transducers connected to delay elements at positions with large inclinations at both ends of a theoretical delay pattern to increase the angle at which grating lobes of high intensity are generated, thereby producing tomographic images. Instead, we connected a large number of ultrasonic transducers to the central delay element, which has a small slope, within the range where the grating lobe is acceptable in terms of image quality, thereby suppressing the increase in the number of transmitter/receiver circuits and delay elements.

In this way, by optimally setting the number of ultrasonic transducers connected to one delay element, we can create a low-cost ultrasonic device that minimizes the number of delay elements and transmitting/receiving circuit blocks within the range of acceptable image quality. It can be a sonic diagnostic device.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing an embodiment of the present invention, and FIG.
3 is a block diagram showing the configuration of the transmitter/receiver, FIG. 4 is a diagram for explaining the delay pattern, and FIG. 5 is a diagram showing the delay pattern of the prior art. , FIG. 6 is a block circuit diagram of a device according to the prior art. 10... Theoretical delay pattern, 11... Actual delay pattern, 3.30... Delay circuit, 4.40... Transmitting/receiving circuit, 5.50... Ultrasonic transducer selection circuit, 6...・Ultrasonic probe, 31, 32, 33, 34. 35. 36, 301, 302
゜303...Delay element, 41.42, 43, 44, 45, 46, 47゜401,
402.403.404... Transmission/reception circuit block, 6
0... Ultrasonic vibrator, 61.62, 63, 64, 65, 66.67°601,
602.603.604...Ultrasonic transducer block.

Claims (1)

[Claims] 1) Set the focus position in the depth direction of the subject, emit ultrasound, receive the reflected waves to obtain one-dimensional tomographic image data on one scanning line in the depth direction, A transmitting/receiving device for transmitting and receiving ultrasonic pulses of an ultrasonic diagnostic apparatus that obtains two-dimensional tomographic image data by electronically moving in the scanning direction and visualizes this image data. An ultrasonic transducer is moved in the scanning direction to contact the specimen and transmit an ultrasonic pulse into the specimen using an electrical signal as a transmission signal as an input signal, and to receive a reflected wave and output an electrical signal as a received signal. a plurality of ultrasonic probes arranged in a row, and a plurality of delays that apply delay amounts to the transmitted signal and the received signal, each of which is determined from an arc-shaped theoretical delay pattern corresponding to the focal position for each of the ultrasonic transducers. a delay circuit including a delay element; a transmitting/receiving circuit including a transmitting/receiving circuit block that outputs the transmitted signal and amplifies the received signal, corresponding to each of the delay elements; the ultrasonic transducer and the transmitting/receiving circuit; In the transmitter/receiver of an ultrasonic diagnostic apparatus comprising an ultrasonic transducer selection circuit that changes the position of the scanning line by changing the connection relationship with the block, The number of the ultrasonic transducers connected to the transmitting/receiving circuit block is smaller than that of the transmitting/receiving circuit block connected to the delay element located near the center of the theoretical delay pattern. Transmitting/receiving device for sonic diagnostic equipment.