JPS62148656A - Linear array ultrasonic diagnostic apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a linear array ultrasonic diagnostic apparatus, and more particularly to a linear array ultrasonic diagnostic apparatus effective for high-magnification observation.

(Prior Art) In recent years, many linear array ultrasonic diagnostic devices are equipped with a digital scan converter, and many also allow selection of several display magnifications such as tomographic diagnosis mode. Furthermore, most display images on a CRT using standard television signals. However, when changing the display magnification, the conventional linear array ultrasonic diagnostic apparatus changes the li input clock and readout clock around the frame without changing the sound ray density. An example of this case will be explained with reference to FIG.

Assume that under normal conditions with a display ratio of 1x, the probe emits 224 ultrasonic beams (hereinafter referred to as sound rays) with an interval of 0.375 mm, and the diagnostic depth is 15 cm. , the number of picils, which is the vertical component of the sound ray, is 40.
Set to 0. Find the frequency of the write clock to the frame at this time.

The speed of sound is 1540 m/s, and the sound wave reaches a depth of 15 cm before returning, so the time t required for the round trip is t −2X
0.15 (In ＞/ 1540 (m /s ＞=
195μs The first pixel is 15 to make the Viquerel number 400
Since it is 1/400 of cm, ' + = 195 μs/400 = 487.5 ns Therefore, the frequency [ is r = 1/487.5 (ns> = 2, 05 M) - (z = 2 MHz). The readout clock is 12MH2 due to the relationship with the scanning frequency of the display device.This relationship is shown in Figure 4 (a) and (b).
, as shown in (c). Next, double the display magnification. This means that 1/2 the depth of the diagnostic section 1 is observed at the same display image size compared to when the display magnification is 1, and the number of pixels remains unchanged at 400. Since it is necessary to store in the frame memory the reflections from a distance that is 1/2 of that when the display magnification is 1, the frequency of the write clock must be set to 4 MHz, which is twice that when the display magnification is 1. However, since the number of sound rays does not change, the image written in the frame memory stores pixels with high density in the vertical direction, as shown in FIG. 4(E).

However, compared to the previous version, Lee's is the same, simply having 2-8 vertical increments, but the resolution is twice as high. Since there is no change in the number of sound rays in the horizontal direction (
The interval is the same as (b). Show this 'r-F? When displayed, the display screen displays 400 pixels in the same size, so the image when the display magnification is 2x is displayed as 2-8 and 41' in the vertical direction. Is the horizontal direction 1'+? If it is the same as +, the image of the diagnosed area will look different from the actual shape, so the fourth
In order to obtain a similar triangular image 17 as shown in the example in the figure, it is necessary to enlarge the image twice in the horizontal direction, and therefore the frequency of the read clock is halved to 6MH2 for enlargement.

(Problems to be Solved by the Invention) When the display magnification is doubled as shown in the previous example, the following problems occur.

(1) The resolution in the sound ray direction (vertical direction) improves, but the resolution in the element direction (horizontal direction) does not change.

(2) In the vertical direction, 400 pixels are displayed on the same size display screen, so the correspondence between the frame memory and the coordinates on the CRT remains the same, but in the horizontal direction, the correspondence between the coordinates is unchanged because it is enlarged regardless of the blue line. It is necessary to convert for each different A8 rate, which complicates the digital transmission of images and the processing of digital files.

(3) M-lock with different frequencies for different magnifications,
It must have a readout clock, and must also have cut-off frequencies corresponding to the respective frequencies of the Δ/D converter and low-pass filters installed before and after the D/to converter. . Therefore, the degree of freedom in selecting the magnification is limited by the hardware described above.

The present invention has been made in view of the above points, and its purpose is to eliminate the above-mentioned drawbacks and to provide a near-array ultrasonic diagnostic apparatus.

(Means for Solving the Problems) The present invention solves the above-mentioned problems in a linear array ultrasonic diagnostic apparatus equipped with a digital scan converter and capable of selecting display magnifications such as a tomographic diagnosis mode. The sending/receiving lifetime data based on the rate data set by the means is sent to the sending means and the receiving means via the storage means.
Furthermore, the number of sound rays is increased or decreased according to a set magnification, and the read address signal is set to a constant frequency.

(Function) Set the multiplication S← using the condition setting means, calculate the number of phonos to increase or decrease the number of sound rays according to the multiplication data, and set the generation order and delay amount of the elements based on the desired number of sound rays. are determined and transmitted sequentially. On the other hand, the read clock from the frame memory remains unchanged, and images are displayed in accordance with the rate of increase in the number of sound rays.

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

First, the mechanism of sound ray generation will be explained with reference to FIG. The ultrasonic deep probe (as shown in the figure) emits a large number of T8 sound waves 1! It is made up of ii' elements. The sound ray is created by a plurality of superblind wave emitting Iff elements. Figure 3 shows an example of making one sound or gland with one element. Also, one element can be used to create multiple sound rays.

Now, I will explain the mechanism of creating one tree of sound rays from multiple elements. First, the elements S and [ at both far ends of the sound ray (1) are oscillated, then the elements e and C on both sides thereof are oscillated, and after a further delay, the element d at the center is oscillated. In this way, if the oscillation time is set appropriately to avoid oscillation, the oscillated waves will interfere with each other, parts of the same phase will strengthen each other, and parts of the opposite phase will cancel each other out, as shown in Figure 3. Sound rays are formed. In the example of the mouth, 5 elements are used and the focus is connected to the desired position (for example, 3 cm).The adjacent sound ray (2) has element d, primary e, g,
The f8 oscillation is further delayed. The oscillation timing of each element is R
The transmit/receive focus is stored in AM. Even in reception, the center part is moved 1 and the phase is matched in a 8-point pattern.

In order to eliminate the above-mentioned disadvantages, it is sufficient to increase the number of sound rays according to the display magnification. In Figure 2, the display magnification is doubled and the write clock frequency is increased from 2MHz to 4MHz.
Although it is unavoidable to use M l-1z, the number of sound rays is 2.
12M1-1z with the doubled I read clock as it is
However, since the sampling points are doubled, this shows that the aspect ratio of 1:1 is maintained even if the image is enlarged.

FIG. 1 is a block diagram of an embodiment of the invention.

1 is a wave transmission trigger generation circuit, and 2 is a wave transmission delay control circuit. Transmission trigger signals 1 to 1 are output from the generation circuit 1 and enter the transmission delay $l control circuit. On the other hand, the mask controller 3 outputs data based on the set display magnification, the focus calculation processor 4 calculates the transmission/reception focus, determines the small transmission/reception delay, and outputs the transmission/reception delay data. Writing to focus RAM5. At this time, if the magnification is 11, the sound ray bit is 1 compared to the 1x sword.
/n times the focus of each sound and gland so that the number of sound rays is n IffC). The transmission delay Ll control circuit 2 controls the oscillation order and delay ffi e I of each element based on data from the focus RAM 5, and sends a signal to each element of the wave transmission circuit 6. The wave transmitting circuit 6 excites the radiator 1 and transmits a sound ray of n4a from the probe 7. The sound waves returned from the subject enter the reception delay circuit 8. The transmission/reception delay data from the focus RAM 5 enters the reception delay control circuit 9, and when the wave is received, the phase of the received sound wave is aligned by the delay line of the detour path 8,
The received wave signal is sent to the next stage logarithmic amplifier circuit 10, and the received wave level is approximately equalized and inputted to the ilJ wave reducer 11. The reduction filter 11 receives the magnification data from the mask controller 3 and selects a cutoff frequency that is suitable for the frequency of the write clock according to the magnification. On the other hand, the mask con [-
Based on the magnification data from the roller 3, the write/read address generator 14 sends a Δ/D clock to the A/D converter 12 when the display magnification is n times, compared to when the display magnification is 1 times. give. Also, the write address of the frame memory 13 is set to n18, and the received wave data is written to the frame memory 13.
let them get involved. D/A from write/read address generator 14
The clock has a constant frequency regardless of the magnification, reads out the image (τξ data from frame frame 13,
The signal is converted into an analog signal by 2, passed through the video filter 16 which is a reduction filter, and the same 1v1 signal is added by the sum circuit 17 and displayed on the monitor 18 as a (voice T\telephone signal).In the above circuit, The part that is different from the conventional one is the signal path shown by the double line in FIG. 4. A new signal circuit for the focus RAM 5 and Frame memory 1 with the clock of
It is now possible to read from 3. Therefore D/
The video filter 16, which is a reduction filter installed after the A converter, no longer needs to change the readout clock for each magnification, so there is no need to use filters with different cutoff frequencies depending on the magnification, and one type can suffice. Ta. On the other hand, the correspondence between the coordinates of the frame memory 13 and the absolute display position on the CRT monitor 18 does not change depending on the magnification. This increased the degree of freedom in changing the magnification.

It should be noted that the present invention is not limited to the examples listed here.
A ROM capable of storing the focus of all sound rays may be used instead of the focus RAM and the focus measurement processor. Also, the focus meter version [! The mask controller 3 may act as the sensor 4.

(Effects of the Invention) As described above in detail, according to the present invention, when the magnification in the sound ray direction is increased in order to improve the resolution, the resolution is improved both in the sound ray direction and in the element direction. Furthermore, even if the magnification is changed, the display absolute position on the CRT and the frame memory location 1 correspond, making image processing easier. Furthermore, there is no need to change the frequency of the readout clock, and only one constant for the readout clock oscillation and the cutoff frequency of the video filter are required. Furthermore, since the number of sound rays increases in proportion to the display magnification, there is a disadvantage that the frame rate (the number of images displayed in a certain period of time) decreases, but there is a formula for deciding whether to give priority to image quality or frame rate. It is only necessary to add a circuit that can simultaneously turn the bibicle of () in the direction of the element of the frame memory according to the display magnification when the selection switch is turned on. Alternatively, a circuit for interpolating images in the horizontal direction may be added.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a comparison diagram with before the change when the magnification is changed by implementing the present invention, and Fig. 3 is an explanatory diagram of creating sound rays by an oscillation element. , Fig. 4 is a diagram of the z-j ratio with respect to the 'structure plane when the F-rate is changed in the conventional device. Control circuit 3...Master control []-ra 4...Brosselli for focus meter 5...Focus RAM 6...Wave transmission circuit 7...Probe 8...
Receiving wave R detour 9... Receiving delay control circuit 1o...
・Logarithmic amplifier circuit 11...reducing filter 12...A
/ Dhen IIj! Device 13...Frame memory 1
4...Write/read address generator 15...D/Δ converter 16...Video filter 17...Domei signal addition circuit 18...Monitor

Claims (1)

[Claims] In a linear array ultrasonic diagnostic apparatus equipped with a digital scan converter and capable of selecting display magnification such as tomographic diagnosis mode, transmission and reception delay data based on magnification data set by the condition setting means are received with the transmitting means via the storage means. the number of sound rays is increased or decreased according to the set magnification,
A linear array ultrasonic diagnostic apparatus characterized in that the read address signal has a constant frequency.