RU2121812C1 - Device for forming acoustic waves for lithotriptor - Google Patents

Abstract

FIELD: medical engineering. SUBSTANCE: device has piezoelectric units arranged along radiating reflector perimeter, immersed into liquid and connected to electronic control unit of pulse setter. Acoustic transducer of the pulse setter unit and piezoelectric unit concentrating members are directed into the reflector focus. Each piezoelectric unit is manufactured as flat metal-coated piezoceramic plate. Excitation and concentrating conductors are itched in its metal coating. Depth and topology of the itched pattern corresponds to radiated frequency being not lower than 4•10⁶ Hz. Controllable discrete delay line with decoder changes feeding pulse delay time of each piezoelectric member and allows to control acoustic grain form in the device focus. EFFECT: enhanced effectiveness of treatment. 3 cl, 3 dwg

Description

 The device relates to electronic medical equipment and can be used in medicine for remote crushing of body stones, thermal spot treatment of internal organs, as well as for the processing of superhard materials in technology.

 Known lithotripters manufactured, for example, by the French company EDAP-01, contain 800 piezoceramic plates emitting plane acoustic waves through a liquid medium in the focus of a spherical reflector, a shock wave with a speed of t = 300 ns. In the presence of a reflector with a diameter of about 1 m, the dimensions of the focal constriction (overlapping of a converging and diverging wave) are small, which makes it possible to avoid pain at the time of the session and to abandon the use of anesthetics. In addition, the small size of the focal “grain” allows the use of that type of lithotripter for the thermal point effect on neoplasms of the body.

 However, for a more accurate and effective point effect on benign and malignant tumors of the body, it is necessary to influence them with higher frequencies, i.e. high-speed hydroshock pulses, which will reduce the size of the focal "grain", i.e. to get an opportunity when scanning slowly, for example, a tumor is more effective to destroy it without affecting the organ. In addition, in the presence of a large number of piezoelectric elements with possible adjustment of the response time of each or several groups — to obtain different forms of acoustic “grains” in focus, i.e. act on the stone as an acute form of "grain", and a predetermined program blunted in any sequence, and this increases the efficiency of crushing (due to the decrease in the size of the front of a hydroshock wave).

 A prototype of the invention can be an ultrasonic device for crushing stones by a shock wave (FP, application N 0391378, A 61 B 17/22, 1990), in which there is a reflector with piezoelectric elements fixed along its emitting perimeter, immersed in a liquid, connected through a signal processing element to a control electronic unit including a computer and an acoustic sensor. Piezoelectric concentrators and an acoustic sensor are directed into the focus of the reflector.

 The main disadvantages are the limited speed of the known device and the inability to control the shape of the acoustic grain in focus, which, in turn, worsens the process of crushing stones of the body and heat treatment of tumors or neoplasms of organs.

 The purpose of the invention is the creation of a device without the above disadvantages, namely, improving the process of crushing stones of the body and heat treatment of organs by hydroshock waves.

 This goal is achieved by the fact that in the acoustic wave former of the lithotripter containing a reflector, along the emitting perimeter of which there are piezoelectric elements immersed in the liquid and connected to the control electronic unit of the pulse generator, which includes a computer and an acoustic sensor connected to it, while the piezoelectric concentrators and acoustic sensor directed into the focus of the reflector, each piezoelectric element is made of a piezoceramic, in the form of a flat metallized piezoceramic plate etched in etallicheskom coating exciter conductors and a hub topology and depth etched pattern corresponding radiating frequency not lower than 4 MHz, moreover, it is provided with an adjustable delay line with a discrete decoder connected to the computer with the ability to change the delay time of the supply pulse of each piezoelectric element.

 In addition, in the shaper, the shape of the pattern etched in the metallization of the piezoelectric element of the surface acoustic waves is made in the form of parallel lines of the cross-rod or counter-radial lines formed by the pathogen conductors themselves etched in the metallization and has the form of parallel strips directed by their radiating edge to the focus of the reflector. The cycle frequency of the computer of all or groups of piezoceramic elements operating simultaneously must be multiplied by the maximum number of logic elements that receive a single delay value of a single one (ie, the response time of one element, for example, the repeater of unit “1” - K155LN1), taking into account the piezoceramics of surface acoustic waves (SAW) - f = 4 MHz.

 Piezoelectric elements can also be connected via an adjustable discrete delay line to a pulse generator.

In FIG. 1, a shows a block diagram of a lithotriptor acoustic wave former;
in FIG. 1, b, c, d illustrate embodiments of a separate piezoceramic emitter;
in FIG. 2, a, b - electronic circuit of the adjustable delay line.

 The shaper (Fig. 1, a) contains a piezoceramic emitter (piezoelectric element) 1 surface acoustic waves (SAW). The emitter 1 (Fig. 1, b) has a waveguide 3 and, for example, a parabolic concentrator 2 directed to the focus F, an anti-radial design is also possible (Fig. 1, d). The pathogens 4 and 5, as well as the concentrator 3, are etched in the metal coating of the emitter 1. In addition, the emitter 1 (Fig. 1, c, d) can have the pathogens 4 and 5, which are also radiation sources (without concentration of hydroshock waves of the surface of the emitter 1). Position 6 (Fig. 1) reflector housing.

 Each piezoelectric element 1 is connected via a controlled delay line 7 and a matching decoding unit 8 to the computer 10, by means of an acoustic wave sensor 9 directed to the focus F. A teflon separator 11 is provided between the piezoceramic elements 1. Position 12 is a rubber membrane covering the liquid medium of the reflector 6 One embodiment of an electronic circuit for an adjustable delay line is shown in FIG. 2a, where 13 is an inverter microcircuit (for example), each discrete element of which has, for example, its own delay time of 5 ns. The last element is loaded with a PAS-1 piezoceramic element. Discrete elements are connected in series. The input of each is connected to the output of the demultiplexer 14, for example 155ID3. The input of the demultiplexer 14 is controlled from a multi-mode buffer register 15 (for example, K589IR 12, matching unit MBR-15), controlled from the output port of the computer 10. Information is obtained from the acoustic sensor 9 or sound device (ultrasound). In addition, the piezoceramic surfactant emitter 1 can be powered by a matching amplifier 16 of the pulse transformer 17 (Fig. 2, b).

 In the simplest embodiment, FIG. 3, SAW emitters 1 are powered from the pulse generator 18 through matching amplifiers 19 and pulse transformers 17. Moreover, the emitters 1 are made according to the circuit, FIG. 1c, which makes it possible to obtain the cheapest version of the device with a speed that exceeds the known devices by several times, respectively, with a decrease in the “grain” of the focal spot.

 The shaper works as follows.

 After power is turned on, electrical pulses begin to be supplied simultaneously to all piezoceramic elements 1 of surface acoustic waves (SAWs). Radiation of a hydroshock pulse is produced by a thin end layer of a metallized coating with a certain etched shape of the concentrator 3, waveguide 2 or without a waveguide and pathogen 4 and 5. The causative agent is two counter-rod forms (sometimes more) of a conductor etched in the metallization of piezoelectric element 1, energized by pulse A on conclusions. At the moment of impulse A being applied to conductors 4 and 5, the surface of the piezocrystal is deformed, creating a surface acoustic wave (SAW). The frequency range of these waves is hypersonic.

 Piezoceramic elements (emitters) 1 surfactants are strengthened around the perimeter of the reflector 6 - with a separator (Teflon film) 11 between them. The maximum number of emitters is selected based on the measurements of the reflector 6, emitter 1 and separator 11. In the simplest case, the piezoceramic emitter is made according to the scheme of FIG. 1, c. In this radiator, the conductors 4 and 5 etched in the metallization are simultaneously radiating elements forming a hydroshock wave. Reflector 6 is filled with spindle oil (another type of oil with a low viscosity is also possible). The acoustic impulse sensor 9 is mounted in the center of the reflector and connected to the input ports of the computer 10. In the computer 10, the pulse coming from focus F is analyzed by amplitude and duration. After analyzing the pulse coming from focus F, the preparation of the operation of all piezoceramic elements at the same time begins. 1. The generated pulse signal with the corresponding pulse synchronization signals arrives from the output ports of the computer 10 (meaning high-speed personal computers of the type RS-486) to matching decryptor blocks 8 (multi-channel pulse amplifiers with multi-stage decoders from the logical series). A pulse signal from the output of each multi-stage decoder 8 is supplied to each adjustable delay line 7. The output of the delay line 7 is a load — a SAE piezoceramic emitter 1 (according to the design of Fig. 1, a, 1, b or 1, d). From the outputs of the decoders 8 (Fig. 2), the pulses are fed to the input of the multi-mode buffer register 15 (MVR, for example, type K 589 IR 12). From the output of this register, the signal goes to a decoder 14 (for example, a demultiplexer type K 155 IDZ), and then to the inputs of the inverter 13 (for example, K 155LN1). To obtain a delay for the required time, the corresponding output of the demultiplexer is turned on, which connects any of the inverter inputs to the delay circuit. The pulse is delayed by the delay value of one discrete element 13. For example, the maximum delay of the pulse running to the emitter 1 will be when applying a pulse to the input B of element 13. The maximum delay time for one emitter 1 will be the sum of the delay time of each inverter 13 (there are one the housing can be 8, 16, 32 pieces, etc.) and the maximum delays of the discrete elements included between the computer 10 and the emitter 1.

 To obtain a different shape of the “grain” of acoustic water hammer (peaked, blunt or alternating) at the time of crushing stones or processing biological tissue using an address (software) method, the shape of the water hammer is set. In a simplified version of processing a biological object with a shock wave, all piezoceramic emitters of 1 surfactant are triggered simultaneously, and this allows to increase the frequency (decrease the constant) of the pulse time to 5 MHz and higher. The supply of pulses can occur with processing frequencies up to 10,000 Hz (all piezoelectric elements triggered by one focus).

 In addition, it is provided that the piezoceramic emitters 1 of the surfactant are supplied with pulsed transformers 17. Using transformers, the pulse duration is shortened, which improves coordination while maintaining pulsed power. Currently mounted device with piezoceramic surfactant option 1, century

Claims (3)

 1. A lithotriptor acoustic wave generator comprising a reflector, along the emitting perimeter of which there are piezoelectric elements immersed in a liquid and connected to a control unit of a pulse generator, including a computer and an acoustic sensor connected to it, while the piezoelectric concentrators and acoustic sensor are directed to the focus of the reflector, characterized in that each piezoelectric element is made piezoelectric in the form of a flat metallized piezoceramic plate etched in a metal coated with conductors of the pathogen and the concentrator with the depth and topology of the etched pattern corresponding to a radiating frequency of at least 4 MHz, and equipped with an adjustable discrete delay line with a decoder connected to a computer with the ability to change the delay time of the supply pulse of each piezoelectric element.  2. The shaper according to claim 1, characterized in that the etched pattern of the conductors of the pathogen and the hub is made in the form of parallel strips, counter-rod or anti-radial, while their radiating edge is directed to the focus of the reflector.  3. The shaper according to claim 1, characterized in that the piezoelectric elements are connected to a pulsed generator via control discrete delay lines.

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