JPS63234959A - Ultrasonic remedy 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] [Industrial Application Field] The present invention provides an ultrasonic treatment device for destroying and treating an affected area, such as a kidney stone, by irradiating the affected area with concentrated ultrasonic shock waves. Regarding.

[Conventional technology]

A stone destruction device as an example of an ultrasonic treatment device is known, for example, in Japanese Patent Application Laid-open No. 145131/1983.

FIG. 9 is a sectional view showing a schematic configuration of a transmitter in the above device. As shown in the figure, this transmitter includes a large number of piezoelectric elements 1
By arranging them in a spherical mosaic pattern,
A shock wave generator 2 is configured, and the shock wave generator 2 is brought into contact with a living body 4 via a liquid-sealed bag 3 filled with a medium such as water, and the stone is removed from the affected area in the kidney 5, that is, the object to be treated. 6, the stone 6 is destroyed by concentrating the ultrasonic shock waves from the large number of piezoelectric elements 1.

The ultrasonic shock wave is generated by applying a pulse voltage to the piezoelectric element 1 from a shock wave generation circuit (not shown). In order to discover and confirm the location of the calculus 6, a mechanical scanning type ultrasonic probe 7 is attached to the center of the shock wave generator 2, and an ultrasonic observation device (not shown) is attached to the probe 7. is now connected. - [Problems to be Solved by the Invention] The piezoelectric element 1 in the device shown in FIG. child is used. However, since ceramic resonators generally have a high Q,
For example, the sound pressure waveform of an ultrasonic wave generated even when driven by a pulse is a waveform W with a long duration that oscillates around a zero sound pressure level as shown in FIG. 10. When a signal having such a vibration waveform is converged and enters a living body as described above, when the negative sound pressure is large, cavitation may occur in the living body and normal living tissue may be destroyed. In addition, the degree of convergence is also worse than when using normal pulses.

Therefore, in the conventional device, a damping material is pasted on the back side of the ceramic resonator, and the Q of the resonator is extremely reduced in order to widen the band. JS11 diagram (a
) As shown in (b), an attempt has been made to create the vibration waveform shown in (b) in the same figure, which is almost similar to the drive pulse waveform shown in (a) in the same figure and has a small negative sound pressure. As another example of countermeasures, pulse driving is performed using a flat part (broadband part) 9 where the impedance characteristic 8 of the vibrator is below the resonance frequency fc as shown in Fig. Some even realize waveforms.

However, of the two sides mentioned above, the former aims to widen the band by pasting damping material together, so
There is a problem that the conversion efficiency becomes extremely poor. Further, in the latter case, since a region in which the vibrator impedance is high and Q is small is used, there is a problem of poor conversion efficiency, as in the former case.

Therefore, the present invention can generate an ultrasonic shock wave with a vibration waveform with low negative sound pressure and a high degree of convergence, and can provide highly safe and accurate treatment to living organisms, as well as have high conversion efficiency and low power consumption. The purpose of the present invention is to provide an ultrasonic treatment device that requires less use.

[Means for solving problems]

The present invention has taken the following measures in order to solve the above problems and achieve the objectives. That is, the resonance frequency of each of the plurality of transducers arranged to constitute an ultrasonic transmitter is varied for each transducer according to the distance from the central axis of the ultrasonic transmitter, and the resonant frequency is set within a constant frequency range. It was arranged in a distributed manner.

[Effect]

By taking such measures, the Q of the resonator
It is possible to generate a vibration waveform with low negative sound pressure while keeping the conversion efficiency high by setting it high. As a result, cavitation in the living body is less likely to occur, and safety to the living body can be improved.

Furthermore, the degree of convergence at the convergence point is increased, allowing the affected area to be treated accurately and the influence on areas other than the treated area being reduced, making it possible to further improve safety.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention, and shows an ultrasonic transmitter 10.
FIG. As shown in the figure, this ultrasonic transmitter 10 is
A plurality of ring-shaped vibrators 11 and 12 are arranged in a spherical shape. As shown in FIG. 2, the resonant frequency fc of each vibrator increases as the distance from the center of the ultrasonic transmitter 10 increases toward the outside. They are distributed in a correspondingly increasing manner. When the transmitter 10 having such a configuration is excited with pulses and the ultrasonic shock waves are focused in the living body,
The sound pressure distribution at the convergence point is as follows.

FIG. 3 is a schematic diagram of an apparatus shown for examining the sound pressure distribution at the convergence point of ultrasonic shock waves.

In order to simplify the explanation, in Fig. 3, the oscillator 1 is
1.12~ are arranged one-dimensionally. Reference numeral 13 in the figure is a pulse generator, and 14 is a delay line for making fine adjustments so that the phases of the generated ultrasonic waves coincide at the convergence point.

Now, the central axis 15 of the transmitter 10, that is, the vibrator 11,
Assuming that n spatial frequency component elements A in the direction of the central axis of the ultrasonic pulse generated from 11- are distributed in a linear step shape as shown in FIG. 4, the direction of the central axis 15 at the convergence point is The sound pressure distribution P (x) is expressed as sin n yrΔrt sln , Δrt″5ln2π(fL+−Δf)x. Note that fL indicates the lowest frequency among the step frequencies, and Δf indicates the stellar width of the frequency. show.

According to the above equation, the sound pressure distribution at the convergence point is as shown in FIG. In other words, the negative sound pressure is small, the pulse width is relatively small, and the degree of convergence is high.

Next, the sound pressure distribution in the direction perpendicular to the central axis 15, that is, in the azimuth direction will be considered. The spatial frequency component B in the azimuth direction of the ultrasonic pulses generated from the transducers 11, 12, etc. is approximately represented by a linear step frequency as shown in FIG.

As shown in FIG. 6, the spatial frequency component o in the azimuth direction of the vibrator located at the center of the transmitter 10 is zero.

In other words, the sound pressure distribution in the azimuth direction at the convergence point is expressed as f
This is obtained by substituting L-0. This can be expressed graphically as shown in Figure 7. That is, the negative sound pressure is still small and the pulse width is also narrow.

In addition, when distributing the resonant frequencies of each transducer 11, 12, etc., the negative sound pressure of the ultrasonic vibration waveform can be further reduced by weighting the amplitude of the excitation pulse and the number of arranged transducers. Can be done.

For example, as shown in Figure 8(a), if the amplitude of the low frequency and several components is increased, the pulse width will become wider as shown in Figure 8(b-), but the negative sound pressure will be further suppressed. Waveforms can be obtained.

Note that the present invention is not limited to the embodiments described above, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

〔Effect of the invention〕

According to the present invention, the following effects are achieved.

■Since the vibration waveform of the ultrasonic shock wave at the convergence point has a small negative sound pressure, cavitation does not occur in the living body, increasing safety for the living body.

■The vibration waveform of the ultrasonic shock wave at the convergence point has a narrow pulse width, so the degree of convergence of the ultrasonic shock wave to the treatment area is high, allowing for accurate treatment and safety for other living tissues. Sexuality increases.

■Since a high-Q resonator can be used, conversion efficiency is high, power consumption is low, and the device is simple.

[Brief explanation of the drawing]

Figures 1 to 8 (a) and (b) are diagrams showing one embodiment of the present invention. Figure 1 is a front view of an ultrasonic transmitter, and Figure 2 is a dispersion of the resonant frequency of each vibrator. Figure 3 is a schematic diagram of the device for considering the sound pressure distribution at the convergence point of the ultrasonic shock wave, and Figure 4 is the distribution of spatial frequency components in the central axis direction of the ultrasonic pulse. Figure 5 is a diagram showing the sound pressure distribution at the convergence point corresponding to Figure 4. Figure 6 is a diagram showing the distribution of spatial frequency components in the azimuth direction perpendicular to the central axis of the ultrasonic pulse. , Fig. 7 is a diagram showing the sound pressure distribution at the convergence point corresponding to Fig. 6, and Fig. 8 (a) and (b) are diagrams showing the ultrasonic vibration waveform when the amplitude of the low frequency band is greatly modulated. It is. 9 to 12 are diagrams showing the prior art. FIG. 9 is a sectional view of an ultrasonic transmitter, and FIGS. 10 to 12 are diagrams for explaining the drawbacks of the prior art. DESCRIPTION OF SYMBOLS 10... Ultrasonic wave transmitter, 11. 12... Plural ring-shaped transducers, 13... Pulse generator, 14... Delay line, 15... Central axis of transmitter, fc...resonance frequency, fA...spatial frequency component in the central axis direction, fB...
・Spatial frequency component in the azimuth direction, fL...lowest frequency,
No...Distance from the center of the transmitter. Applicant's representative Patent attorney Atsushi Tsuboi Figure 1 Figure 2 Figure 1 Mo Figure 7 Figure 9 Figure 10 Figure 11, Figure 12 Procedures Book 1939 4° i 0 Commissioner of the Patent Office Black 1) Yu Akira 1, Indication of the case Patent Application No. 62-67519 2, Name of the invention Ultrasonic treatment device 3, Person making the amendment Relationship to the case Patent applicant (037) Olympus Optical Industry Co., Ltd. 4, Agent Tokyo TJ&E Building 1, 3-7-2 Kasumigaseki, Chiyoda-ku, Miyako
00 Telephone<)3(502>3181 (main representative)
6. Illustrated text of the amendment 7. Contents of the amendment

Claims (1)

[Claims] The resonant frequencies of the plurality of transducers arranged to form an ultrasonic transmitter are varied for each transducer according to the distance from the central axis of the ultrasonic transmitter, and distributed over a constant frequency range. An ultrasonic treatment device characterized in that: