KR840001818B1 - Ultrasonic diagnosis apparatus - Google Patents

Abstract

An ultrasonic diagnosis apparatus is provided with a plurality of phased array transducer elements arranged in a row. The number of simultaneously driven transducer elements is changed in response to a rate pulse to increase the ultrasonic scanning line density without increasing the number of the transducer elements, while the position of the focal point is adjusted to maintain the minimum width positon of the ultrasonic beam maintain the minimum width positon of the ultrasonic beam provided by the group of the simultaneously driven transducer elements substantially constant irrespective of the change of the number of the simultaneously driven transducer elements.

Description

Ultrasonic Diagnostic Device

1 is a block diagram of a conventional apparatus.

2 is an explanatory diagram of a vibrating element driving method for improving scan line density.

3 is an explanatory diagram of a straight array group sound source beam pattern.

4 and 5 are explanatory diagrams of the principle of the present invention.

6A, 6B and 6C are block diagrams showing the configuration of the apparatus of the present invention.

7 is a diagram illustrating the configuration of an embodiment of the electronic poshing circuit of the present invention.

The present invention relates to an ultrasonic diagnostic apparatus which improves ultrasonic gaze line density by changing the oscillatory embroidery used simultaneously in a plurality of vibration elements at every repetitive pulse or at a predetermined period, and at the same time corrects the focus along with the number of vibration elements. will be.

In the ultrasonic diagnostic apparatus having a probe having a large number of vibration elements of this kind, when the transducer is transmitted and waved by one vibration element of a constant coefficient every repetition cycle, the directional center is the vibration element. Move by one center interval. This means that the ultrasonic scanning line density is determined by the center distance of the vibrating element. Therefore, in order to increase the ultrasonic scanning line density, a vibrator having a small width of the vibrating element and a small distance between the vibrating elements is required and a large number of vibrating elements are required. Do. However, this is also a manufacturing problem, the device is turned on, the handling is inconvenient and expensive.

Therefore, a technique for shifting the directional center by 1/2 of the center distance of the vibrating element by changing the number of vibrators used at the same time for each repetition period is already known to solve the above-mentioned drawback. This method will be described below with reference to FIGS. 1 and 2.

In FIG. 1, reference numeral 1 denotes a repetitive pulse generator, reference numeral 2 denotes an oscillator control signal generator, reference numeral 3 transceiver, and reference numeral 4 denote an transducer having n vibrating elements arranged. Electrodes can also be used. Code 5 is a detector, code 6 is a B-mode luminance modulated voltage generator, code 7 is a distance-directed sine wave generator, code 8 is a beam-positioning shunt voltage generator, code 9 is B It is a mode indicator.

In the following operation, the repetitive pulse generator 1 generates repetitive pulses of a constant frequency in accordance with the diagnosis distance, and its output is connected to the vibrating element control signal generator 2, and a vibrating element which transmits and receives simultaneously for each repetitive pulse It generates such a signal to change by one in three, four, as shown in FIG. This signal is connected to the transceiver 3, ultrasonic waves are transmitted and received for each vibrating element, detected by the detector 5, and connected to the B-mode luminance modulation voltage generator 6. On the other hand, the output of the repetitive pulse generator 1 is input to the distance direction sine wave generator 7 to generate a triangular wave according to the diagnostic distance for each repetitive pulse. At the same time, a voltage corresponding to the beam center of the vibrating element group which is input to the beam position indicating voltage generator 8 and operates for each repetitive pulse is generated. The outputs of the B modulated luminance modulated voltage generator 6, the distance sweeping wave generator 7, and the beam position indicating voltage generator 8 are connected to the B diode display 9, as shown in FIG. Scanning is performed as shown. That is, by gradually changing the number of vibration elements transmitted and received simultaneously to m and m + 1, the directivity center of the vibration element group can be moved by 1/2 of the center distance of the vibration elements. Therefore, the B mode image of the same ultrasonic scanning density can be obtained with the number of vibration elements of the conventional half.

The first repetitive pulse uses three vibrating elements for transmission and three vibrating elements for receiving, and the next repetitive pulse uses three magnitude error elements for transmitting and four for receiving. The method of making one quarter of each vibrating element interval is also known.

However, as described above, as the method for densifying the scanning line density and the instantaneous scanning line interval without changing the oscillation element spacing, the oscillation phoneme embroidery used simultaneously for each ultrasonic wave changes, so the ultrasonic wave or the water wave diameter is changed. Because of this change, the pattern of the transmitted or received ultrasonic beam changes every time the vibration element is driven.

Hereinafter, the beam pattern by the change of a wave or a wave diameter is demonstrated.

In general, the ultrasonic beam pattern is determined by the aperture D, the ultrasonic wave wavelength λ, the focal point F of the ultrasonic beam, and the like when the vibration element group is driven.

For example, if the ultrasonic beam pattern is obtained by the method of drawing the ultrasonic beam width by the surface oscillator (Inuyama et al., Japan Ultrasonic Expansion Lecture Paper Collection, November 48), the third degree in the case of F <D ² 4λ same. In this figure, the position where the beam width becomes minimum and the beam width becomes thin is a position in which the distance of X is in the depth direction from the point of transmission, and the aperture at this time is D and the focus is F. This distance X ₀

X ₀ = 1 (F1 2λ / D ₂ ) (1)

Can be obtained as

Therefore, by changing the number of the oscillation element at the same time using the value of X ₀ of the equation (1) because the diameter (D) is changed it is also changed. That is, in order to change the oscillation element used at the same time for each repetition pulse (per ultrasonic wave transmission), the repetition pulse is different for each repetition pulse at the reflection point of the echo signal by the beam in which the value of X ₀ changes. It is a defect that the good site of resolution becomes uneven and the resolution of the part for diagnostic purposes deteriorates.

For example, when the vibration element pitch is 1.5 mm, the ultrasonic wave wavelength is 0.64 mm (frequency = 2.4 MHz, sound velocity = 1530 mm / sec), the focus is 50 mm in the propagation direction, and the number of driving vibration elements is 8, 7, the value of X ₀ The error of about 10%.

Such a change in the X ₀ value is remarkably deteriorated due to the above-described change in the beam pattern when the accuracy of the ultrasonic diagnostic apparatus is further improved.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ultrasonic diagnostic apparatus having a function of correcting the focus of each wave ultrasonic beam while simultaneously changing the number of vibrating elements to be used simultaneously for every four pulses or at certain predetermined periods in order to solve the above-mentioned drawbacks. It is.

In the present invention, when the aperture D is changed according to the number of vibration elements used simultaneously in the above formula (1), the position where the ultrasonic beam becomes the minimum width, that is, the distance X ₀ from the point of delivery to the wave direction is kept constant. To change the focus F at the same time.

Hereinafter, the principle of the focus correction method of the present invention will be described with reference to FIGS. 4 and 5. FIG.

For example, the beam pattern obtained when the vibration element pitch is 1.5 mm, the ultrasonic wavelength is 0.64 mm (frequency = 2.4 MHz, sound velocity = 1530 m / sec), the focus is 60 mm, and the number of reference vibration elements is 8 is obtained by the above-mentioned surface roughness method. 4, the beam pattern when the number of vibration elements is changed to 9 and the number of vibration elements is used simultaneously in the next cycle is indicated by a solid line.

At this time, as described above, the position (value of X ₀ ) at which the beam width becomes minimum due to the change of the vibrating element drive diameter D caused by the change of the number of vibrating elements is different. Therefore, by adjusting the delay amount of each vibration element in the case of nine vibration elements, the minimum width position (value of X ₀ ) of the beam when nine vibration elements are used is matched with eight cases. 5 shows a state where the number of reference vibration elements is eight, the number of vibration vibration elements is decreased by one, and the number of simultaneous driving vibration elements is seven, and the value of X ₀ is the same as in the case of increasing one vibration element. The focus is to correct it.

On the other hand, to narrow the overall beam width for a wide field of view,

F = D ² / 4λ (2)

It is known that this is done. That is, in this case, since the aperture D changes because the number of vibration elements used simultaneously changes, the position of the focal point F changes, which is corrected in the same manner as described above.

An embodiment of the present invention will now be described with reference to FIGS. 6A, 6B, 6C, and 7. In FIG. 6A, reference numeral 10 denotes a repetitive pulse generator, reference numeral 11 denotes a control circuit for controlling the number of simultaneous vibration elements and focus, reference numeral 12 denotes a transmission electronic pocus circuit for determining the focus of an ultrasonic transmission beam, Reference numeral 13 is a group of circuits connected to each vibrating element to generate pulses for driving each vibrating element, 14 is an ultrasonic transducer in which a plurality of vibrators are arranged at least in line, and 15 is an ultrasonic echo An amplifier for amplifying the signal, code 16 is a receiving electronic pocus circuit for determining the connection point of the reception echo, code 17 is amplifying and detecting a detector code 18 is a signal output by the detector 17 Is a display unit for marking the B-mode ultrasonic image.

Referring to the operation of the apparatus, as described in the prior art, the control circuit 11 changes the number of vibration elements used for each repetition pulse to change the number of vibration elements simultaneously driven for each repetition pulse to increase the scan line density. Is output to the pulse generating circuit group 13, and the control circuit 11 sends a control signal to the transmitting electronic focusing circuit 12 and the receiving electronic focusing circuit 16, and simultaneously uses the vibrating element. Even if the number of vibration elements varies with the number, the focus of the beam at the time of transmission / reception is adjusted so that the position where the width of the ultrasonic beam becomes the minimum (value of X ₀ described above) is the same.

The focusing may be adjusted when the same number of vibration elements are used in transmission and reception, and when the vibration elements used in transmission and reception are different, the transmission electronic pousing circuit 12 and the reception electronic pousing circuit ( 16), the focus at the time of transmission / reception is adjusted so that the X ₀ at the time of transmission / reception coincides with each other.

To change the distance X ₀ from the wave point at the point where the ultrasonic beam width becomes minimum in response to the change in the number of vibration elements,

It can be seen that this can be done with a focus.

On the other hand, in order to make the overall position (depth) of the ultrasonic beam width minimum at all times according to the change in the number of vibration elements, the relational expression (2) is used, but in the correction of this focus, the transmission electronic focusing circuit ( 12) and the receiving electronic focusing circuit 16.

The focusing method is not limited to the method described above, but the focusing position is adjusted by the transmitting electronic focusing circuit 12 and the receiving electronic focusing circuit 16 so as to be focused according to the diagnostic purpose.

An embodiment of the present invention described above will be described with reference to FIGS. 6B and 6C.

The number of vibration elements to be driven simultaneously is m and (m + 1), for example. There are (m + 1) delay elements and a tap group in the electronic pousing circuit 12 for transmission. The delay time control signal is output from the transmission delay line selection tap data generator in the control circuit 11, and the position of each tap, that is, the delay time, is controlled by this control signal.

The switch 19 and the transducer 14 each have n (m + 1 <n) switches and vibrating elements, each of which enables an output signal from the high voltage switch switching data generator in the control circuit 11. The opening and closing timing is controlled by this.

Accordingly, m or (m + 1) vibrating elements emit an ultrasonic beam and receive beams reflected from a site for diagnosis. The received signal is applied to the receiving electronic focusing circuit 16 via the switch 19 and the amplifier 15. However, the received (m + 1) signals are relatively delayed in phase and out of phase. For this reason, the phase is corrected by the receiving electronic focusing circuit 16. The receiving electronic pousing circuit 16 has (m + 1) delay elements and tap groups like the circuit 12. The position of each tap, i.e., the delay time, is controlled by a delay time control signal which is the output of the receiving delay line tap selection data generator in the control circuit 11. The output of each delay line tap selection data is added to the adder and applied to the detector 17 in the next step.

With this configuration and operation, in the present invention, the minimum width position (X ₀ ) of the ultrasonic beam is controlled despite the change of the number of vibration elements (eg m and m + 1) driven simultaneously by controlling the delay time of each delay element and the tap. ) Will be constant.

Correction of the focus performed by the above-described transmission electronic pouse circuit 12 and the reception electronic focusing circuit 16 will be described in more detail with reference to FIG. Since the electronic focusing circuits 12 and 16 for transmission and reception have exactly the same circuit configuration, only the transmission electronic focusing circuit will be described here.

Focusing of the ultrasonic beam transmitted and received by the ultrasonic vibration element 19 is achieved by controlling the amount of delay by each delay line 20 (L ₁ to L _n ) connected to each vibration element 19. The control of the delay amount includes a plurality of taps 21 connected to the delay lines 20 (L ₁ to L _n ) at predetermined intervals, and the delay lines 20 (L ₁ to L _n ) and the vibrating element 19. This is performed by appropriately selecting and switching the desired tab 21 by the switch element 22 connected in between. Each switch element 22 and each oscillation element 19 are connected by an output line 23, and in the control circuit 11, a plurality of convolutional wires (corresponding to the number of taps) to each switch element 22 ( 24) is connected. That is, when the number of vibrating elements used simultaneously in the control circuit 11 is selected, the above-described control signal for focus correction is output to the switch element 22 via the large throw line 24 so that a predetermined tap is applied. Select and focus on the desired location.

Therefore, the control circuit 11 selects the number of vibration elements to be used at the same time and outputs a control signal for driving each vibration element to the pulse generator germ 13, and also for the transmission electronic poshing circuit 12. In order to correct the focus according to the number of driving vibration elements, a control signal for selectively switching the tab 21 of the delay line 20 connected to the vibration element is outputted to the switch element 22.

In this case, for example, it is also conceivable to store in the storage element the group of vibration elements used simultaneously for each repetitive pulse and the delay amount corresponding thereto.

In addition, it is also contemplated to use a surface, a delay line element, or a charge coupled device (CCD) instead of the above-described strand as the delay element. In this case, the delay line 20 and the switch element 22 in FIG. 7 may be replaced with a CCD or the like.

As described above, in order to improve the peak line density in an ultrasonic diagnostic apparatus that generates a mode ultrasonic image using a probe in which a plurality of vibrating elements are arranged in a line, the vibrating elements are used at the same time for each repetitive pulse or at a predetermined period. When the number is changed, the beam pattern is changed by changing the diameter of the ultrasonic beam at the time of angular transmission. As a result, the present invention provides a defect that the ultrasonic beam beam affecting the image quality is out of the minimum width. The present invention includes a control circuit for controlling the amount of delay of the electronic focus circuit at the time of transmission and reception at the same time as the switching of the number of vibration elements. Therefore, the focus is corrected according to the change of the vibrating element used at the same time for each repetitive pulse or at a predetermined period, and the resolution of the target position of the diagnosis is made constant by always matching the minimum width portion of the ultrasonic wave to a predetermined position in the subject. To keep.

Claims (1)

A transducer 14 arranged with a plurality of vibration elements, a circuit 10 for generating a repetitive pulse, a control circuit 11 for controlling the number of simultaneous driving vibration elements and a group of driving vibration elements, and an ultrasonic wave during transmission An electronic focusing circuit 12 for determining the focus of the beam, an electronic focusing circuit 16 for determining the focus of the ultrasonic echo at the time of reception, a circuit 15 for amplifying and detecting the ultrasonic echo, and And an indicator 18 for displaying the ultrasonic intensity by changing the intensity of the nose on the ultrasonic waves, and simultaneously changing the number of vibration elements to be driven at regular intervals, while the ultrasonic beams by the driving vibration element group have a minimum width. Ultrasonic diagnostic apparatus, characterized in that for correcting the focus so that the position becomes constant.

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