JPH0375051A - Calculus crushing device - Google Patents

Abstract

PURPOSE:To high accurately decide the agreement between the focus of a piezoelectric element and the location of a calculus by properly setting a time gate for a sound speed difference between coupling fluid in an applicator and the living body and for a change of depth of the calculus. CONSTITUTION:An imaging ultrasonic probe 8 is insertion-arranged in the central part of a piezoelectric element 3 with an ultrasonic wave transmitted into the body of a patient 6 through the probe 8, and by receiving a reflected wave of the transmitted ultrasonic wave, an ultrasonic picture is displayed on a CRT display 18. A time gate, before a treatment start switch 14 is pressed, is wide set, and a start address A of a memory 16, corresponding to the start timing, is always fixed. Now in the case of a calculus 7 assumed in a shallow position, a distance for propagating coupling fluid 5 is increased, and the maximum position P' of a reflected wave signal is also displaced. A start address B' and an end address C' of the memory 16 are displaced to the rear by the amount of the maximum position P' displaced. Thus by variably setting the time gate, positioning accuracy of the depth direction of a focus to a location of the calculus can be more enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a stone crushing device that crushes and treats stones, and particularly relates to a stone crushing device that uses a piezo element to irradiate shock waves to stones.

(Prior Art) In recent years, a method of non-invasively crushing stones by irradiating shock waves from outside the body has been widely used mainly in the treatment of kidney stones. As means for generating shock waves, underwater discharge, electromagnetic induction, micro-explosion, piezo elements, etc. have been proposed. Among these, JP-A-80-14513
The method using a piezo element described in Publication No. 1 etc. is as follows.
It has excellent features such as no consumables and the ability to control the shock wave intensity arbitrarily. Furthermore, if a piezo element is used, it is also possible to receive reflected waves from the focal region.

Therefore, for example, in Japanese Patent Application Laid-Open No. 80-191250 and Japanese Patent Application No. 81-149562, immediately before emitting a shock wave from a piezo element, an ultrasonic wave weaker than the shock wave is transmitted and the intensity of the reflected wave is detected. A technique is described in which, if a relatively strong reflected wave is returned, it is determined that the focus of the piezo element matches the stone site, and a shock wave is emitted. This makes it possible to perform treatment without erroneously irradiating shock waves to normal tissues other than stones, thereby reducing side effects and improving fragmentation efficiency.

By the way, when the reflected wave intensity was actually measured using the configuration described in Japanese Patent Application No. 81-149562, it was found that when a piezo element having a sound field with a focus size (half width) of 2 x 19 mm is used, the intensity of reflected waves for a model stone with a diameter of 11 mm is The detection ability in the horizontal direction of the focal point is approximately 511I11 (half width of the reflected wave peak), which is extremely high precision. On the other hand, since the detection ability in the focal depth direction is as rough as about 30 degrees, it is not possible to accurately determine whether the focal point of the piezo element matches the calculus site simply by detecting the peak value of the reflected wave. As a countermeasure, there is a method that applies a time gate corresponding to the depth of the stone to the RF signal of the reflected wave, extracts only the reflected wave from the vicinity of the focal point, and then detects the peak value of the amplitude of the reflected wave. It has been devised. but,
This method has the following problems.

As shown in FIG. 6, since the sound velocities CI and C2 generally differ between the coupling liquid 21 in the applicator and the inside of the living body 22, refraction of ultrasonic waves occurs at the boundary between the two. Further, if the depth of the calculus 23 differs as shown in FIGS. 6 and 7, a difference occurs in the propagation distance between the coupling liquid 21 and the living body 22.

If there is a change in the refraction state of the ultrasonic wave or a change in the depth of the stone site, the timing at which the peak value of the reflected wave is received changes. Therefore, if the width of the time gate is narrow, the peak value of the reflected wave may not be detected, and it may become impossible to determine whether the focal point and the stone site match. Furthermore, if the width of the time gate is set wide, there is a risk that if a larger reflected wave is returned from a region farther away from the focal point, it may be determined that the focal point and the calculus region coincide.

(Problems to be Solved by the Invention) As mentioned above, in the conventional technology, due to the influence of the sound speed difference between the coupling liquid in the applicator and the living body, the change in the depth of the stone, etc. There was a problem in that it was difficult to detect the peak value of the reflected wave near the focal point, and it was impossible to correctly determine whether the focal point and the stone site were coincident.

This invention appropriately sets the time gate in response to the sound speed difference between the coupling liquid in the applicator and the living body, and changes in the depth of the stone, and matches the focus of the piezo element with the stone site with high precision. It is an object of the present invention to provide a stone crushing device that can be used for stone crushing, has few side effects, and has high crushing efficiency.

[Structure of the Invention] (Means for Solving the Problems) The stone crushing device of the present invention has a driving method that selectively applies a high voltage for generating a shock wave and a lower low voltage to a piezo element as a driving voltage. a voltage applying means; a means for recording a reflected wave signal from within the body when a low voltage is applied to the piezo element; a first peak detecting means for detecting a peak value of the reflected wave signal and its generation timing; means for setting a time gate according to the generation timing of the peak value detected by the first peak detection means; second peak detection means for detecting the peak value of the reflected wave signal within the set time gate; means for comparing the peak value detected by the second peak detection means with a predetermined threshold value and determining the magnitude relationship; and means for switching the drive voltage applied to the drive voltage to a high voltage.

(Operation) A piezo element is normally driven at a low voltage to irradiate weak ultrasonic waves into a patient's body. In this state, the reflected wave signal is received by the piezo element and recorded in, for example, a memory. The peak value (maximum amplitude value) of this recorded reflected wave signal and its generation timing are detected. This detection may target the waveform of the entire period of the reflected wave signal, but it is preferable to target only the waveform within the first time gate set in advance near the focal point of the piezo element.

Here, the operator aligns the focus and the stone while checking the magnitude of the peak value of the reflected wave signal on the display, and instructs the time gate setting by operating a switch, for example. Based on this instruction, the timing of occurrence of the peak value of the reflected wave signal is detected, and a second time gate shorter than the first time gate is set according to this timing. Thereafter, the peak value of the reflected wave signal within the set second time gate is detected, and when the peak value exceeds the threshold value, the driving voltage of the piezo element is switched to a high voltage, and a crushing shock wave is emitted.

As a result, an appropriate time gate is set without being affected by the sound velocity of the coupling liquid in the applicator or the depth of the stone in the body, so the coincidence of the focus of the piezo element and the stone site can be determined with high precision.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings. 1st
The figure shows a configuration diagram of a stone crushing device according to an embodiment of the present invention.

In FIG. 1, a therapeutic applicator 1 has a support 2;
A plurality of ring-shaped piezo cords 3 supported by a support body 2 and arranged concentrically; and a water bag 4 attached to the front surface of the piezo element 3 and containing a coupling liquid (for example, water) 5 inside. It is mainly composed of. The piezo element 2 has a spherical shell shape as a whole, and is capable of converging and irradiating shock waves for crushing and treating a stone 7 in the body of a patient 6 and ultrasonic waves for positioning toward the stone site.

Further, in this embodiment, an imaging ultrasonic probe 8 is inserted into the center of the piezo element 3. An imaging device 9 connected to the ultrasound probe 8 transmits ultrasound waves into the body of the patient 6 via the probe 8 and receives the reflected waves, thereby converting an ultrasound image (for example, a B-mode tomographic image) into a CRT image. It is displayed on the display 18. The configuration of this imaging device 9 is similar to an ultrasonic imaging device that is put into practical use as an ultrasonic diagnostic device, so a detailed explanation will be omitted.

A high voltage drive circuit 11 and a low voltage drive circuit 12 are selectively connected to the piezo probe 3 via a switch 1o. Switch 10. High voltage drive circuit 11 and low voltage drive circuit 1
2 is one set in the figure, but if the piezo element 3 is divided into a plurality of parts, a plurality of sets are provided corresponding to each piezo element. Further, the reflected wave signal received by the piezo element 3 is input to the A/D converter 13 via the switch 10, and after being converted into a digital signal with an appropriate number of bits,
It is taken into CPU (central processing unit) 15. C.P.
U15 is a treatment start switch 1 built into the handset.
4 and the command from the keyboard 17, switch 1
0, high voltage drive circuit 11, low voltage drive circuit 12, memory 16 and CRT display 18 are controlled.

Next, the operation of this apparatus will be explained with reference to the flowchart shown in FIG. When the device is started, the switch 10 is first switched to the low voltage drive circuit 12 side under control from the CPU 15, and the low voltage drive circuit 1 is switched from the CPU 5 to the low voltage drive circuit 12 side.
2 is supplied with a timing signal. As a result, weak ultrasonic waves are emitted from the piezo element 3 and irradiated into the body of the patient 6 (step 85). The reflected wave from the body of the patient 6 when this weak ultrasound is irradiated is received by the same piezo element that emitted the ultrasound and becomes an RF multiplied signal (reflected wave signal), which is sent to the A/D converter 10. CPU via
15, and then recorded in the memory 16 (step S2). In the memory 16, the amplitude of the reflected wave signal and the reception timing are recorded in association with each other by incrementing the write address in accordance with the reception timing (reception time) of the reflected wave signal.

Next, in step S3, it is checked whether the treatment start switch 14 has been pressed, and if it has not been pressed, the process moves to step S4. In step S4, the CPU 15 selects a relatively wide first
According to the time gate (for example, a 40 μs wide gate corresponding to the depth dimension -30+am), the data at the address of the memory 16 corresponding to the time gate is searched, and the peak value (maximum value of amplitude) and this The generation timing (reception timing) of the peak value is detected. Further, at this time, the peak value is displayed on the CRT display 18 under the control of the CPU 15.

The operator operates the applicator 1 while viewing the peak value displayed on the CRT display 18 and the ultrasound image.
The focus of the piezo element 3 and the stone 7 are aligned (step 85). After completing this positioning, when the operator presses the treatment start switch 14, the CPU 1
5 detects the peak value of the reflected wave signal recorded in the memory 16 by the next timing signal and the address on the memory 16 where the peak value is written (this corresponds to the generation timing of the peak value). and then press keyboard 17 in advance.
A relatively narrow second time gate (for example, a gate with a width of 6 μs corresponding to the dimension in the depth direction of −5 m+*) is set before and after the peak value (step 85).

Thereafter, a peak value is detected within the address range corresponding to this second time gate and displayed on the CRT display 18 (step 87).

Next, in step S8, the CPU 15 compares the peak value within the second time gate with a threshold value inputted in advance via the keyboard 17 to determine the magnitude relationship, and if the peak value is equal to or greater than the threshold value, switches the switch 10. Switch to the high voltage drive circuit 11 side and send a strong shock wave to the piezo cord 3 with the next timing signal.
The light is emitted from the source to irradiate the stone 7 (step S9).

Moreover, if the peak value is less than the threshold value, the process returns to step S1 and the weak ultrasonic wave irradiation is repeated again.

Normally, a stone is crushed by shock wave irradiation of about 1,000 to 2,000 shots, but when the crushing is confirmed on the ultrasonic image, the operator presses the treatment start switch 14 again. By operating the treatment start switch 14 again, the CPUI 5 switches and fixes the switch 10 to the low voltage drive circuit 12, and returns to measuring the reflected wave intensity at the wide second time gate.

3 to 5 are timing charts showing the relationship between the above operations and the first and second time gates. In each figure, (a) represents a reflected wave signal, (b) represents a time gate, and the horizontal axis represents a time axis (corresponding to an address on the memory 16). FIG. 3 is a diagram before pressing the treatment start switch 14, and the time gate is set wide (first time gate).
, memory 1 corresponding to the start timing of the time gate.
The start address A of 6 is always fixed. FIG. 4 is a diagram immediately after pressing the treatment' start switch 14, and the second time gate, that is, the start address B and end address C of the memory 16, is set based on the maximum position (timing of occurrence of peak value) P. It can be decided. When the treatment start switch 14 is pressed again, the state returns to the state shown in FIG. 3.

Moreover, if the calculus 7 is located shallowly, the distance over which the coupling liquid 5 is propagated becomes longer. Generally, the speed of sound in a living body is 1
540 m/see, and water at 36°C has a slower sound speed of 1520 m/see, so the timing at which the reflected wave is received is delayed as shown in Figure 5, and the maximum position P' of the reflected wave signal is also It shifts.

In this case, according to this embodiment, the start address B' and end address C' of the memory 16, which is the second time gate, are shifted backward by the amount that the maximum position P' is shifted. By making the time gate variable in this way, it is possible to further improve the accuracy of positioning the focal point and the stone site in the depth direction.

This invention can be implemented with various modifications other than the embodiments described above. For example, in the embodiment, the treatment start switch 14 has the function of starting the time gate setting operation, but a separate switch for starting the time gate setting operation may be provided. Further, the switch operation for starting the time gate setting operation may be performed automatically instead of manually.

Furthermore, as for the method of setting the time gate, a weighting function other than the rectangle may be applied.

[Effects of the Invention] According to the present invention, the coincidence between the focus of the piezo element and the stone site can be detected with high accuracy regardless of the difference in the depth of the stone or the refraction of the shock wave due to the difference in the speed of sound, and there are no side effects. This makes it possible to provide a stone crushing device with high crushing efficiency.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a stone crushing device according to an embodiment of the present invention, FIG. 2 is a flowchart showing a treatment procedure for explaining the operation of the embodiment, and FIGS. 3, 4, and 5 6 is a time chart showing the relationship between the reflected wave signal and the first and second time gates in the same example, and FIGS. 6 and 7 are diagrams schematically showing the refraction of the shock wave when the depth of the stone is different. . 1... Applicator 2... Support 3... Piezo element 4... Ice bag 5... Coupling liquid 6... Patient 7... Stone 8... Ultrasonic probe 9. ...Imaging device lO...Switch 11...High voltage drive circuit 12...Low voltage drive circuit 13...A/D converter 14...Treatment start switch 15...CPU 1B... Memory 17... Keyboard (8... CRT display

Claims (2)

[Claims] (1) In a stone crushing device that crushes and treats stones by irradiating them with shock waves generated by a piezo element, the piezo element has a high voltage for generating shock waves as a driving voltage, and a lower low voltage. A driving voltage applying means for selectively applying a driving voltage, a means for recording a reflected wave signal from within the body when a low voltage is applied to the piezo element, and a peak value of the recorded reflected wave signal and its generation timing. a first peak detection means for detecting; a means for setting a time gate according to the generation timing of the peak value detected by the first peak detection means when a predetermined instruction is given; and within the set time gate. a second peak detecting means for detecting the peak value of the reflected wave signal at the second peak detecting means; a means for comparing the peak value detected by the second peak detecting means with a predetermined threshold value and determining a magnitude relationship; and means for switching the drive voltage applied from the drive voltage application means to the piezo element to a high voltage when the peak value detected by the peak detection means of item 2 is determined to be equal to or higher than a threshold value. Crushing equipment. (2) In a stone crushing device that crushes and treats stones by irradiating shock waves generated by a piezo element to stones in the body, the piezo element has a high voltage for generating shock waves as a driving voltage and a lower low voltage. drive voltage applying means for selectively applying a drive voltage; means for recording a reflected wave signal from within the body when a low voltage is applied to the piezo element; a first peak detection means for detecting the peak value of the reflected wave signal and its generation timing; and when a predetermined instruction is given;
means for setting a second time gate shorter than the first time gate according to the generation timing of the peak value detected by the first peak detection means; and the reflected wave within the set second time gate. a second peak detection means for detecting a peak value of a signal; a means for comparing the peak value detected by the second peak detection means with a predetermined threshold value and determining a magnitude relationship; a second peak detection means A stone crushing device comprising means for switching the drive voltage applied from the drive voltage application means to the piezo element to a high voltage when the peak value detected by the drive voltage applying means is determined to be equal to or higher than a threshold value.