JPH02193653A - Dynamic focus system ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To improve a frame rate and to improve resolution using a delay line having fixed delay quantity without increasing cost by equipping the subject ultrasonic diagnostic device with a reception signal image data storing means, a data write-in control means, a switching timing control means, etc. CONSTITUTION:For a scanning beam 1, in a first transmission, while image data are written an image memory 10 at a depth position indicated with a continuous line, the image is never written in the memory 10, and null is obtained in the periods of noise generating periods (tap switching periods) P1, P2, and P3. However, in a second transmission, the image data are written in the image memory 10 at another depth position indicated with a broken line. Consequently, the P1, P2, and P3 parts in the first transmission can be compensated with the broken line (the second transmission), and an omitted part in the second transmission can be compensated with the continuously line (the first transmission). Consequently, image quality can be improve. Further, it becomes unnecessary to provide plural delay circuit systems for each piezoelectric transducer, composition of the device can be simplified, and the cost of the device can be made low in cost.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ultrasonic diagnostic device that performs electronic focusing, and particularly to an ultrasonic diagnostic device that focuses on a plurality of tilted walls by switching the taps of a delay circuit with a fixed delay amount. Regarding diagnostic equipment.

[Conventional technology]

An electronic scanning method is generally used as a beam scanning method in an ultrasonic diagnostic apparatus. In this electronic scanning method, the ultrasonic beam is made to have directivity by giving different delay amounts to each of the plurality of micro-oscillators that make up the probe.

In such an electronic scanning method, so-called electronic focusing, in which the beam is focused at an arbitrary position, is possible.

In this electronic focusing method, for example, ultrasonic waves reflected from a focal point within a living body are received by each micro-oscillator, and an appropriate delay time is given to each signal obtained by each of these micro-oscillators. The phase of the signals from the focal point is matched and the signals are added. The focus setting during wave transmission is similar, and by giving each micro-oscillator a delay time similar to that for wave reception, the transmitted ultrasonic beam is focused at a predetermined focus point.

By using the electronic focusing method as described above, it is possible to perform a transmission dynamic focusing method (multi-step focusing method) for obtaining images with good resolution over the entire region from the shallow part to the deep part of the living body.

In the transmission dynamic focus method, multiple focal points are set according to the depth of the living body, ultrasound is transmitted and received to each of these focal points, and the data obtained at each focal point is stored in memory and transmitted into a single focal point. This is to create scanning line data.

In such a transmission dynamic focusing method, an image with very high resolution can be obtained, but when the focal point is n points, it is necessary to perform transmission and reception three times to obtain one scanning line. Therefore, the time required to obtain one frame of data, ie, the frame rate, becomes small. Therefore, image quality can be effectively improved for organs that move relatively slowly, such as the abdomen.

C. Problems to be Solved by the Invention] There is a reception dynamic focus method that solves the drawback of the transmission dynamic focus method as described above, that is, the drawback that the frame rate is reduced. This reception dynamic focusing method sets multiple focal points during reception for one transmitted beam, and obtains one scanning line data based on the reception data obtained from each of these focal points. be.

In such a reception dynamic focusing method, the disadvantage of a low frame rate as described above is eliminated. However, since it is necessary to set a plurality of focal points for one scanning beam, it is necessary to accurately control the amount of delay of the delay circuit over time (according to depth). For this reason, it is conceivable to control the amount of delay using a variable delay line, or to provide a delay line with a fixed amount of delay that has multiple taps and to control the amount of delay by switching and selecting the taps. . Here, if the delay amount is controlled by switching the taps of a delay line with a fixed delay amount, noise at the time of tap switching will appear on the monitor. Therefore, two sets of delay circuit systems are provided for each vibrator.
The taps on the delay line that are not capturing image data are switched to prevent noise from appearing on the monitor when switching taps.

However, when using the variable delay line, it is difficult to accurately control the delay time, and
When a fixed delay line is used, two sets of delay circuit systems are required for each vibrator, which poses a problem of significantly increasing costs.

The purpose of this invention is to improve the frame rate compared to the conventional transmission dynamic focus method, and to provide ultrasound diagnostic images with improved resolution by using a delay line with a fixed delay amount without increasing cost. The object of the present invention is to provide a dynamic focus type ultrasonic diagnostic device that can obtain the following.

[Means to solve the problem]

The dynamic focus ultrasonic diagnostic apparatus according to the present invention has a delay circuit provided corresponding to each transducer constituting the probe, and focuses by switching and selecting a plurality of taps provided in the delay circuit. This is what you set. and tap selection means for switching and selecting the taps of the delay circuit, image data storage means for storing the received signal obtained from the selected tap as image data, data writing control means, and switching timing control means. and data replacement means.

The data writing means prohibits writing of received wave data during a period in which noise occurs due to tap switching when writing data to the image data storage means. The switching timing control means controls tap switching timing. Further, the data rewriting means is for replacing the received wave data during the noise generation period due to the tap switching with other image data/data.

[Effect]

In this invention, a single transmitted beam is focused in a plurality of areas and reflected echoes are received. In this respect, it is similar to the received wave dynamic focus method. At this time, it is necessary to switch the taps of the delay circuit when setting each focus, but noise is generated when switching the taps.

During this noise generation period, writing of received wave data to the image data storage means is prohibited, and data containing noise is removed from the image data. At this time, the tap switching timing is controlled such that, for example, the noise generation period for each transmission beam differs in the depth direction.

Image data missing due to such writing control can be obtained by, for example, transmitting a beam twice in the same scanning line direction and changing the tap switching timing for each beam in the depth direction. Interpolate data or create interpolated data in a direction orthogonal to the depth direction. Furthermore, interpolation is performed using data from the previous frame.

As a result, the frame rate is improved compared to the conventional transmitting dynamic focusing method, and diagnostic images with good resolution can be obtained without the need for multiple delay circuits as in the conventional receiving dynamic focusing method. .

〔Example〕

FIG. 1 is a block diagram of an ultrasonic diagnostic apparatus according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a probe consisting of a plurality of transducers, which generates an ultrasonic beam based on a pulse signal from a wave transmitting circuit 2 and receives reflected echoes from inside the living body. Amplifiers 3a to 31 amplify received signals from each vibrator. Delay lines 4a to 41 have a fixed delay amount, and have a plurality of taps for controlling the delay amount. 5a-51 are analog multiplexers for switching and selecting a plurality of taps of delay lines 4a-41, and data for tap selection is stored in RAMs 6a-61.

7 is an adder that adds the received signals selectively output by each analog multiplexer 5a to 51, 8 is a circuit that processes the output of the adder 7 into an analog signal, and 9 converts the output of this analog signal processing circuit 8 into a digital signal. A/D to convert
It is a converter. IO is an image memory in which image data of reflected echoes converted into digital signals is stored according to a predetermined address signal; 11 is this image memory 1;
This is a CRT monitor that displays 0 image data.

Reference numeral 12 denotes a control unit composed of a CPU, RAM, ROM, etc., which includes a switching timing control unit 13 for sending data for tap switching to the RAMs 6a to 61, and a switching timing control unit 13 for writing data to the image memory 10. The data write control means 14 generates an address.

In this embodiment, in order to fill in data missing due to write control, the transmission beam is transmitted twice in the same scanning line direction, and the switching timing control means 13 controls the tap switching timing for the first and second times. Timing control is performed to shift in the depth direction.

Next, the operation will be explained.

The wave transmission operation is similar to that in the conventional reception dynamic focus method, but in this embodiment, the ultrasonic beam is transmitted twice in the same scanning line direction. In addition, the ultrasonic beam is transmitted without particularly setting a focus.

The reflected echo from within the living body is received by the probe 1, and this received signal is amplified by the amplifiers 3a-31 and input to each delay line 4a-41. The taps of each delay line 4a-41 are switched and controlled approximately every tans by corresponding analog multiplexers 5a-51.

As a result, data for tap switching, in which focus is set on a plurality of depth regions within the living body and data with good resolution is taken in, is sequentially output from the RAMs 6a to 61 to the analog multiplexers 5a to 51.

In this way, the received signals for each transducer whose delay amount is controlled for each depth are added by the adder 7, processed by the analog signal processing circuit 8, and sent to the A/D conversion circuit 9. is input. The received signal input to the A/D conversion circuit 9 is
It is converted into a digital signal and written into the image memory 10 as image data.

When writing the image data into the image memory 10, an address signal is output from the data write control means 14 of the control section 12, and the image data is written based on this address signal. This write control will be explained in detail below.

The timing of tap switching of the delay lines 4a to 41 is set by the switching timing control means 13 of the control section 12, and this data is stored in each of the RAMs 6a to 61. Therefore, the control unit 12 can accurately grasp the tap switching timing, that is, the period during which noise occurs. Therefore, during this noise generation period, the data write control means 14 controls so that no image data is written into the image memory 10. That is,
During the noise generation period, an image data write inhibit signal is output while an address signal for writing is output. As a result, image data will not be written to addresses in the image memory 10 that correspond to the noise generation period.

After the above operation is performed for the first ultrasonic beam in a certain scanning line direction, the switching timing control means 13 shifts the tap switching timing in the depth direction and transmits the second ultrasonic beam in that direction. do. Then, image data is written into the image memory 10 by the same operation as described above. The data obtained by this second ultrasonic beam fills in the missing part from the first ultrasonic beam, and all data regarding the scanning beam in that direction is obtained.

FIG. 2 schematically shows this situation.

For example, regarding the scanning beam, in the first wave transmission, image data is written to the image memory 10 at the depth position shown by the solid line, but during the noise generation period (during tap switching) P,, P, P, In this case, no image will be written and it will be blank. However, in the second wave transmission, image data is written into the image memory 10 at the depth position shown by the broken line.

Therefore, the first P+, Pg, and Ps parts are broken lines (2
The missing portion of the second time will be compensated for by the solid line (first time). For the next scanning beam 2, the timing of tap switching is shifted in the depth direction, and in the same manner as described above, the data excluding the noise generation period is transferred to the image memory 1 by the second wave transmission.
Take it into 0. The same applies to the scanning beam 3.

It is desirable that the timing of tap switching in such an operation be varied randomly, but if the movement of the image is gradual, there is no particular problem even if the switching timing is fixed and varied.

In such an embodiment, image data is not written to the image memory 10 during the noise generation period at the time of tap switching, and the noise generation period is compensated for by other data obtained by shifting the timing switching timing in the depth direction.
Image quality can be improved. In addition, since tap switching is performed at different depths for adjacent scanning beams, the data interpolation position will not be on the same line on the monitor, and the diagnostic image displayed on the monitor will not look like an image based on the interpolated data. There is no noticeable deviation. Therefore, there is no need to provide multiple delay circuit systems for each vibrator, as in the conventional wave receiving dynamic focusing method that uses a delay line with a fixed delay amount, resulting in a simpler configuration and lower cost. Become.

[Other Examples]

In the above embodiment, waves are transmitted twice in each scanning beam direction, and the data obtained by these transmissions is used to compensate for missing data during the noise generation period.
Data interpolation may be performed in a direction perpendicular to the depth direction or frame averaging may be performed in one wave transmission.

(a) In the embodiment shown in FIG. 3, a data interpolation circuit 15 is provided between the image memory IO and the monitor 11, and the structure of other parts is the same as that shown in FIG. Note that in this example, waves are transmitted only once in each scanning line direction.

The data interpolation circuit 15 is a circuit that creates interpolation data to compensate for image data missing due to noise, and interpolates data missing due to noise from previous and subsequent data in a direction perpendicular to the depth direction. By widening the range of this data interpolation, the data missing due to noise can be more smoothly connected.

(b) In the embodiment shown in FIG. 4, a frame averaging circuit 16 is provided between the A/D conversion circuit 9 and the image memory 10, and the configuration of other parts is the same as that shown in FIG. It is similar to In this embodiment as well, the wave is transmitted only once in each scanning line direction. Further, for the same scanning beam, the timing is controlled so that the timing of tap switching differs in the depth direction for each frame.

The frame averaging circuit 16 provided in this embodiment averages the data stored at each address of the image memory 10 between the previous frame and the current frame, and writes the averaged image data to the address. It is. As for the noise generation period, the average frame data up to the previous time is held as is. This allows images to be connected more smoothly.

In addition to the configuration shown in FIG. 4, the data interpolation circuit 15 shown in FIG. 3 may be provided.

(C) In the embodiment shown in FIG. 1, the timing of tap switching is made different in the depth direction for each adjacent beam, but there is no particular need to make the timing different when data interpolation is performed by transmitting waves twice.

(d) In addition to the configuration of the embodiment shown in FIG. 1, both or one of the data interpolation circuit 15 shown in FIG. 3 and the frame averaging circuit 16 shown in FIG. 4 may be provided.

〔Effect of the invention〕

According to the present invention, the frame rate is improved compared to the transmitting dynamic focus method, and there is no need to provide multiple delay circuit systems for each vibrator as in the conventional receiving dynamic focus method. . therefore,
It is possible to realize a receiving dynamic focus method using accurate delay control without reducing the frame rate and suppressing cost increase, and it is possible to improve resolution.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an ultrasonic diagnostic apparatus according to an embodiment of the present invention, FIG. 2 is a diagram for explaining its operation, and FIGS. 3 and 4 are diagrams showing other embodiments of the present invention. FIG. 1...Probe, 4a-41...Delay line,
5a-51...Analog multiplexer, 6a-61
...RAM, 10...image memory, 11...
Monitor, 12...Control unit, 13...Switching timing control means, 14...Data writing control means, 1
5...Data interpolation circuit, 16...Frame averaging circuit.

Claims (1)

[Claims] (1) Dynamic focus comprising a probe consisting of a plurality of transducers and a delay circuit each having a plurality of taps and provided corresponding to each transducer, and setting a focus point by switching and selecting the taps. In the ultrasonic diagnostic apparatus, the tap selection means switches and selects the taps of each of the delay circuits, and the image data storage means stores the received signal obtained from the tap selected by the tap selection means as image data. , a data write control means for prohibiting writing of received wave data during a noise generation period associated with the tap switching when data is written to the image data storage means; a switching timing control means for controlling the tap switching timing; and the tap switching timing control means for controlling the tap switching timing. A dynamic focus ultrasonic diagnostic apparatus comprising: data replacement means for replacing received wave data during a period in which noise occurs due to switching with other image data;