JPH0714393B2 - Ultrasonic diagnostic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention is directed to delay data of rasters of ultrasonic beams emitted from each of a plurality of ultrasonic transducers arranged in a straight line. The present invention relates to an ultrasonic diagnostic apparatus that scans a subject by delaying a desired time based on the above to deflect a synthetic wavefront of a radiated spherical wave by an arbitrary angle.

(Prior Art) In an ultrasonic diagnostic apparatus as shown in FIG. 6 having a plurality of ultrasonic transducers 1a, 1b, 1c, ...
1c, ... are delay means 2a, 2b, 2c, which have slightly different delay times.
… By exciting with an electric signal via 2n,
It is possible to control the direction of the composite wavefront 3 of the spherical wave of the ultrasonic beam emitted from 1a, 1b, ...

Therefore, by changing the delay data of the delay means 2a, 2b ... It is possible to draw a desired number of rasters, ... It can be carried out.

When diagnosing a subject with such an ultrasonic diagnostic apparatus, it is important to switch the number of transducers, the number of rasters, the number of focus points, and the like (hereinafter referred to as change factors) at high speed for sector scanning. When switching the deflection factor, it is necessary to change the delay data for transmission and reception for each transducer. These delay data are calculated in advance and stored in storage means such as RAM, and CP is changed every time the change factor is switched.
It is transferred to the control system by U.

The delay data t _d depends on the change factor and is represented by the following equation.

However, x: displacement from the center point, F: focus distance, C: sound velocity.

By the way, as is clear from this equation, the required number of data increases as the number of changing factors increases, so that RAM or the like as a storage means is required to have a large capacity. Further, if it is attempted to realize the above formula by an arithmetic circuit in order to reduce the storage capacity, it takes time to perform the arithmetic operation and the circuit configuration becomes complicated, and in any case, the circuit scale of the device inevitably increases.

(Problems to be Solved by the Invention) As described above, the conventional ultrasonic diagnostic apparatus is required to have a large-capacity storage unit when the number of changing factors increases, and thus the circuit scale of the apparatus becomes large. is there.

The present invention has been made in consideration of the above problems, and an object of the present invention is to provide an ultrasonic diagnostic apparatus capable of switching change factors by using a small-capacity storage means even if the change factors increase.

[Structure of Invention]

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention arranges a plurality of ultrasonic transducers and sets a raster of ultrasonic beams emitted from each transducer to a desired time based on delay data. In the ultrasonic diagnostic apparatus that delays the synthesized wavefront of the radiated spherical wave to scan the object by deflecting the composite wavefront by an arbitrary angle, first and second delay data of a desired number of true rasters are alternately stored.
Memory means for generating a desired number of adjacent interpolation rasters by deflecting the true raster by a desired angle on the basis of the delay data of the adjacent true rasters simultaneously extracted from the first and second storage means. And a calculation means for calculating the delay data for interpolation.

(Operation) A desired number of, for example, 16 pieces of delay data of true rasters are stored in advance in the storage means. Next, an interpolation raster is generated between each of the 16 true rasters by the interpolation delay data calculated by the calculation means based on the delay data of the true raster. For example, by performing 8 interpolation (7 interpolation rasters are generated at equal angles between adjacent true rasters), a total of 120 rasters can be generated. The interpolation operation can be arbitrarily performed by the multiplication function and the addition function provided in the calculation means. As a result, a small capacity of the storage means is sufficient.

(Embodiment) FIG. 1 shows an ultrasonic diagnostic apparatus according to an embodiment of the present invention.
From the transmission / reception delay data creation unit 10 to which the present invention is applied, the CP
The transmission delay data and the reception delay data controlled and output by U11 are added to the transmission delay circuit 12 and the reception delay circuit 13, respectively. The drive signal output from the pulsar 14 controlled by the delay data for transmission is an ultrasonic transducer.
15 is added to cause the ultrasonic beam to be emitted to the subject.
On the other hand, the echo signal reflected by the subject is received by the ultrasonic transducer 15 and then received by the reception delay circuit 13 via the amplifier 16.
Added to.

The received signal, which is controlled by the delay data for receiving and applied to the receiver 17, is A / D converted and stored in the DSC (Digital Scan Converter) 18, and is read and D / A converted and displayed when necessary. Shown above 19. 20 is a raster control circuit.

FIG. 2 shows the configuration of the transmission / reception delay data creation unit 10 of FIG.

Each delay data added to the transmission and reception delay circuits 12 and 13 is created by the creating unit 10.

The transmission / reception delay data t _d is, as described in the conventional example, , And is calculated based on a complex formula. By the way sin
θ is an increasing function in the range of 0 ° <θ <90 °, so θ
As the above formula increases Becomes smaller, so t _d also becomes a simple increasing function with respect to θ. In the case of such a simple increasing function, this value can be mathematically obtained by linear approximation, so-called interpolation method.

Therefore, this interpolation method can be applied to the calculation method of the delay data τ _c for the raster generation of the ultrasonic beam, and when the delay data of the adjacent true rasters are τ _a and τ _b , τ _c = It can be calculated by a τ _a + _b τ _b (a and b are coefficients, and a + b = 1). That is, the delay data (true value) τ _a , τ _b of the true raster is multiplied by a desired coefficient,
By adding, a new raster (interpolation raster) having the delay data τ _c (interpolation value) can be generated between both true rasters. The present invention is provided with a transmission / reception delay data creation unit 10 based on this principle. Delay data τ _a and τ _b for generating a true raster calculated in advance by the CPU 11 are alternately stored in the RAM1 · 21 and the RAM2 · 22, respectively. FIG. 4 shows such delay data τ _a , τ _b
A true raster, which is alternately generated based on the above, and a desired number can be set. The addresses stored in the RAMs 21 and 22 are controlled by the address generation circuit 23 controlled by the raster control circuit 20. coefficient
The ROM 24 stores desired coefficients a and b, and the multiplication circuits 25 and 26 multiply the delay data τ _a of the RAM 21 and the delay data τ _{b of the} RAM 22 by the coefficients a and b, respectively. The result of this multiplication is sent to the adder circuit 27 where it is added, and the delay data τ _c thus obtained is transferred to the transmission delay circuit 12 and the reception delay circuit 13 in FIG. FIG. 5 shows an example in which the intermediate value 3C is interpolated in the combined wavefronts 3a and 3b of the two ultrasonic beams.

Next, the operation of this embodiment will be described.

When an interpolation raster is generated between the true rasters in FIG. 4, delay data τ _c for generating this raster is calculated by the following equation.

τ _c = _a τ _a + _b τ _b a = 1-Δθ ₁ / Δθ b = Δθ ₁ / Δθ This calculation is performed by the multiplication circuits 25 and 26 and the addition circuit 27. The obtained delay data τ _c is used in the transmission / reception delay circuits 12, 13
Transferred to. By the similar operation, desired delay data can be obtained, and interpolation rasters of arbitrary positions and numbers can be obtained. By providing the two RAMs 21 and 22, the delay data τ _a and τ _b of the true raster can be read at the same time, so that the transfer rate of the delay data does not decrease. A desired number of true rasters and interpolation rasters generated between them can be selected. In this case, the coefficients a and b output from the coefficient ROM 24 will change according to the number. As an example, when a true raster and three interpolating rasters are generated (four interpolations are performed), the coefficients a and b take the following values according to each raster.

The delay data for generating one raster is the required number of channels (elements) multiplied by the delay amount. For example, if each is set to 64 ch and 9 bits, it will be 64 × 9 bit delay data. Therefore, if the required total number of rasters is 120, the total delay data is 120 × 64 × 9 bits.

According to the ultrasonic diagnostic apparatus of the present invention to which the interpolation method is applied, when 8 interpolations (7 interpolation rasters are generated at equal angles between adjacent true rasters), the delay data is 16 now.
It becomes x64x9bit and this data should be stored in RAM. Since two RAMs 21 and 22 are used in this embodiment, the delay data to be stored per one is 8 × 64 × 9 bits. Then, interpolation is performed for each corresponding channel. Therefore, the actual delay data to be stored can be reduced to a fraction of the total raster (depending on the interpolation contents).
Large capacity is not necessary.

It should be noted that the delay data of the desired number of true rasters does not need to be evenly spaced, and is rough when the change angle θ is small and finer as the change angle θ is larger, so that the RAM capacity can be further reduced.

FIG. 3 shows another embodiment of the present invention, in which ROMs 28 and 29 are used instead of RAMs 21 and 22, respectively. By using the ROM as the storage means for the delay data in this way, it is not necessary for the CPU to calculate the data,
Since it can be controlled by the probe (vibrator) ID signal, real-time realization becomes easy. Other than this, the same effect as in the case of RAM can be obtained.

The interpolation method, the data capacity, and the like shown in this embodiment are merely examples, and can be arbitrarily changed according to the purpose, application, and the like.

〔The invention's effect〕

As described above, according to the present invention, only the delay data of the true raster is stored in the storage means, and the delay data for interpolation is calculated by the interpolation method based on the delay data, so that a desired number of interpolation rasters can be obtained. Since the change factors are generated, the change factors can be switched by using the storage means having a small capacity even if the change factors increase. Therefore, the required delay data can be quickly obtained without increasing the circuit scale of the device. In particular, since the true raster delay data is alternately stored in the first and second storage means,
Since the true delay data on both sides can be simultaneously read and used for the calculation when calculating the delay data of the interpolation raster between them, there is no time consuming time to calculate the interpolation delay data, and there is no hindrance to ultrasonic diagnosis. It is possible to obtain a peculiar effect that does not occur.

[Brief description of drawings]

FIG. 1 is a block diagram showing an ultrasonic diagnostic apparatus according to an embodiment of the present invention, FIGS. 2 and 3 are block diagrams showing different configurations of a transmission / reception delay data creating section to which the present invention is applied, and FIG.
FIG. 5 is a raster pattern diagram for explaining the present invention, FIG. 5 is a delay characteristic diagram for explaining the present invention, FIG. 6 and FIG.
The drawings are a schematic diagram and a raster pattern diagram showing a conventional example. 10 …… Delay data creation part for sending and receiving, 11 …… CPU, 12 ……
Transmission delay circuit, 13 ... Reception delay circuit, 15 ... Ultrasonic transducer, 21,22 ... RAM, 24 ... Coefficient ROM, 25,26 ... Multiplication circuit, 27 ... Adding circuit, 28,29 ... …ROM.

Claims (1)

[Claims] 1. A composite wavefront of spherical waves emitted is delayed by a desired time by arranging a plurality of ultrasonic oscillators and delaying a raster of ultrasonic beams emitted from each oscillator based on delay data. In an ultrasonic diagnostic apparatus that deflects and scans a subject, first and second storage means for alternately storing a desired number of true raster delay data, and simultaneously fetched from the first and second storage means Calculating means for calculating interpolation delay data for deflecting the true raster by a desired angle based on the delay data of the adjacent true raster to generate a desired number of adjacent interpolation rasters. And ultrasonic diagnostic equipment.