Method for determining the optimal frequency of oscillatory motion of a projectile for force acceleration in a lithotripsy device in the body

Abstract

The invention relates to a method for determining the optimal frequency of oscillatory movement of a projectile for force acceleration in a pneumatic lithotripsy device in the body, comprising the steps of repeatedly accelerating the projectile from a first stopper at the proximal end of an acceleration path to a second stopper at the distal end and from the second stopper to the first stopper, wherein a piezoelectric element is arranged between a counter-bearing arranged at the proximal end and a horn arranged at the distal end and mechanically coupled to the counter-bearing and the horn and the horn has a sonic oscillator arranged at the distal end, wherein the acceleration path is arranged inside the counter-bearing and the horn, the first stopper is arranged at the distal end of the counter-bearing and the second stopper is arranged at the distal end of the horn; detecting an electrical signal from the piezoelectric element caused by the tremor at the first stopper and / or the second stopper due to the projectile; and using the detected electrical signal to control a medium which generates a force and which is used to accelerate the projectile from the first stopper to the second stopper and from the second stopper to the first stopper of the acceleration path.

Description

Technical Field

[0001] The present invention relates to a method for determining the optimal frequency of the oscillating motion of a force-accelerated projectile in an in vivo lithotripsy device and a corresponding lithotripsy device. Background Technology

[0002] Lithotripsy is a method known in the art for breaking down stones in the urinary tract, kidneys, and / or bladder, also known as clods. Most lithotripsy devices use ultrasound, laser, or pneumatic energy to break down these stones.

[0003] Lithotripters known in the prior art comprise a shaft connected to an electrically controlled drive or pneumatic actuator. This shaft is inserted into the patient's anatomy near the point of impaction with the stone, and a waveform is transmitted through the shaft to break up the stone and create a pneumatic hammer or hole effect on it, thereby fracturing the stone into smaller, more easily removable elements, which can then be removed by means of a suction flushing pump. This is a method of in vivo lithotripsy.

[0004] In order to design a system that can break down stones as efficiently as possible, combinations of two systems are known, such as methods using ultrasonic waves and pneumatically generated mechanical impacts.

[0005] It is also known that ultrasonic and pneumatic systems can operate independently or together. If the ultrasonic and pneumatic systems operate together, and the pneumatically driven projectile impacts the sonotrode, this will cause interference to the ultrasonic generator. If the projectile impacts the sonotrode, the impact will also affect the piezoelectric element that generates the ultrasonic waves, thereby inducing a voltage in the generator.

[0006] In some cases of rock crushing systems, this interference can cause control to become unsustainable, resulting in an error message being displayed and the system needing to be restarted.

[0007] It is known that, in the case of a pneumatic system, the highest possible energy impact should be achieved at the highest or most optimal frequency. It is also known that pressure, mass, and acceleration path significantly affect the energy emitted when a projectile impacts an acoustic oscillator. Summary of the Invention

[0008] The object of this invention is to improve upon existing technologies. In particular, an object of this invention is to provide a combined crusher-ultrasonic-pneumatic system with interference-free operation. For example, another object of this invention is to provide a combined system that maximizes the dispersive force of the projectiles used in the pneumatic system. In particular, another object of this invention is to provide a combined system that maximizes the frequency of repeatedly accelerated used projectiles.

[0009] This objective is achieved by a method for determining the optimal frequency of the oscillating motion of a force-accelerated projectile, as described in an embodiment of this application. Further advantageous developments of the invention are indicated in other embodiments of this application.

[0010] This application provides a method for determining the optimal frequency of the oscillating motion of a force-accelerated projectile in an in vivo lithotripsy device, the method comprising the following steps: - The projectile is repeatedly accelerated from a first stop at the proximal end of an acceleration path to a second stop at the distal end and from the second stop to the first stop, wherein a piezoelectric element is arranged between a counter-support arranged at the proximal end and a horn-shaped member arranged at the distal end and the piezoelectric element is mechanically connected to the counter-support and the horn-shaped member, and the horn-shaped member has an acoustic oscillator arranged at the distal end, wherein the acceleration path is arranged inside the counter-support and the horn-shaped member, and the first stop is arranged at the distal end of the counter-support and the second stop is arranged at the distal end of the horn-shaped member; an electrical signal from the piezoelectric element caused by the vibration generated at the first stop and / or the second stop due to the projectile is detected; and the detected electrical signal is used to control a medium that generates force and is used to accelerate the projectile from the first stop to the second stop and from the second stop to the first stop in the acceleration path.

[0011] First, the following terms will be explained:

[0012] The method for determining the optimal frequency of the oscillating motion of the force-accelerated projectile in an in vivo lithotripsy device—particularly a lithotripsy device—can also be understood, in particular, as a method for testing, calibrating, adjusting, or optimizing the function of the lithotripsy device. Specifically, this method is not performed during surgical intervention. The method is performed, for example, at the factory, or before or accordingly after the surgical intervention.

[0013] The term "optimal frequency of the oscillating motion of a force-accelerated projectile in intramural lithotripsy, particularly in pneumatic lithotripsy" can be understood as the maximum frequency in the present context. Even if this frequency is "only" optimized, it is referred to as the optimal frequency in the present context.

[0014] In current lithotripsy techniques, a projectile traveling within an enclosed space accelerates from a first end to a second end of the space, causing it to brake at the second end. This rapid braking releases impact energy, which is transmitted outwards through the projectile to a horn-shaped element and an acoustic oscillator attached to it. After braking, the projectile is preferably transported back from the second end to the first end, at which point it can accelerate again in another direction. In this case, the repetitive motion of the projectile returning from the first end to the second end is designated as oscillatory motion.

[0015] The direct contact between the tip of the acoustic oscillator and the condensate to be decomposed is crucial for the transfer of impact energy.

[0016] The piezoelectric element is preferably operated resonantly with a horn-shaped element and an acoustic oscillator to generate ultrasonic waves.

[0017] Lithotripsy equipment is a device used to perform lithotripsy, especially a handheld device with an endoscope.

[0018] The ultrasonic frequency of the piezoelectric element is preferably 27 kHz. The ultrasonic signal is preferably generated by a signal generator.

[0019] In this case, the acceleration path is a separate spatial region in which the projectile can accelerate from one end to the other. The projectile can slide freely and preferably with low friction within this spatial region.

[0020] The acceleration path preferably extends partially within the horn-shaped member. The end of the acceleration path is preferably connected to the acoustic oscillator at the second stop.

[0021] The anti-support member is preferably a reflector of ultrasonic waves. The horn-shaped member is used to transmit the ultrasonic waves generated by the piezoelectric element to an acoustic oscillator that serves as a waveguide. However, the anti-support member and the horn-shaped member also serve as mechanical retainers for the acceleration path, which are arranged inside the reflector and the horn-shaped member.

[0022] The counter-support and / or flared member have a distinctive hollow cylindrical shape.

[0023] When the accelerated projectile is braked at the first or second stop, a vibration occurs, which also causes the piezoelectric element to vibrate due to the mechanical connection. This vibration induces a voltage at the end of the piezoelectric element due to the piezoelectric effect, and this voltage can be detected by electronic circuitry. Upon impact, the projectile generates high voltage in the piezoelectric element, which disrupts the resonant frequency of the ultrasonic generator. The electronics within the piezoelectric element must be readjusted to restore resonance. This readjustment can be used as a signal to determine the position of the projectile.

[0024] The core idea of ​​this invention is to use information that can be determined from the electrical signal, such as the time or number of times the induced voltage occurs, to adjust the timing actuation of the medium that accelerates the projectile, so that the force transmitted from the projectile to the condensate to be decomposed is at its maximum, and / or the oscillation frequency of the projectile within the acceleration path is maximized and / or optimized.

[0025] Another core idea of ​​the invention is the use of piezoelectric elements for generating ultrasonic waves as sensors to optimize the motion of the projectile within the acceleration path.

[0026] Projectiles can be accelerated by compressed air, electromagnetic impact, or mechanical devices. The medium that generates this force can be compressed air, an electromagnetic field, or mechanical devices. In this context, the term "medium" means "the means of transferring force from a first article to a second article." In this context, the term "medium that generates force" can be understood as any device, any material, or any physical field or force in the above sense. For example, a device used to accelerate a projectile could be a railgun. Additionally or alternatively, mechanical devices, for example, can be used to accelerate a projectile.

[0027] Piezoelectric elements can be excited using ultrasonic frequencies. Therefore, the piezoelectric element is preferably connected to a signal generator that generates ultrasonic frequencies.

[0028] The acceleration path can be implemented using a pipe segment, wherein the first end of the pipe segment has a first stop and the second end of the pipe segment has a second stop. The pipe segment is preferably a hollow cylindrical shape.

[0029] A first valve can be used to introduce compressed air into the pipe section, causing the projectile to accelerate from the first stop to the second stop. Specifically, the compressed air source is connected to the first stop via a check valve, i.e., to the first end of the pipe section. Furthermore, the air displaced by the projectile can be buffered in a storage chamber, which is separated from the acceleration path and / or the pipe section. This buffering is preferably temporary. After the first valve is closed, the buffered compressed air can be used to accelerate the projectile from the second stop to the first stop.

[0030] For compressed air, a pressure between 0.5 bar and 5 bar can be used.

[0031] Specifically, after the first valve closes, the second valve, located between the pipe section and / or the acceleration path and the storage chamber, automatically opens to accelerate the projectile from the second stop toward the first stop.

[0032] The first valve closes, especially after the projectile reaches the second stop.

[0033] The electrical signal from a piezoelectric element can be a power signal, which can be measured using a coil. In this way, the electrical signal can be effectively detected with low loss within the circuitry contained in the piezoelectric element. The principle of current clamping can be used here.

[0034] According to the method of the invention, the power signal measured at the piezoelectric element can also be frequency filtered so that the frequency range in which the piezoelectric element operates is kept away from the circuitry that further processes the measured power signal. Such a filter can be, for example, an RC, RL, or RLC circuit.

[0035] The frequency-filtered power signal is specially rectified to obtain an analog signal.

[0036] For this purpose, a rectifier or a type of rectifier can be used. For example, a buffer circuit can be used.

[0037] Furthermore, at least one threshold of the rectified and frequency-filtered power signal can be determined, corresponding to the arrival of the projectile at the first or second stop. In this way, based on the current intensity generated when the projectile impacts the piezoelectric element, it can be determined whether the projectile impacts the proximal first stop or the distal second stop. The corresponding stopping time can also preferably be determined from the signal. In this case, the location information "distal" is understood as a point on the medical device farther from the user or operator. In this case, the location information "proximal" is understood as a point on the medical device closer to the user or operator.

[0038] A microcontroller can be used to evaluate rectified, frequency-filtered power signals and to assess determined thresholds. Here, the microcontroller can perform reliability testing to minimize or eliminate incorrect measurements or measurement errors.

[0039] This method can be achieved by adjusting the voltage fluctuations caused by the vibrations or impacts of the projectile at the first stop to a predetermined value. The predetermined value can be a minimum value other than zero and can be determined using current electronics. For example, the rule could be a two-point rule, where the predetermined value is a target value, and the actual value moves around the target value. Specifically, this adjustment results in an earlier or later actuation of the second valve based on the actual value, which can release compressed air buffered in the storage chamber, causing the projectile to accelerate from the second stop towards the first stop.

[0040] In another respect, the present invention is implemented by a stone crushing device. This stone crushing device is particularly suitable for performing the above-described method.

[0041] The crushing equipment has a piezoelectric element arranged between a counter-support member arranged proximally and a horn-shaped member arranged distally, wherein the piezoelectric element is mechanically connected to the counter-support member and the horn-shaped member. In this case, a hollow cylindrical acceleration path is arranged inside the counter-support member and the horn-shaped member, and the hollow cylindrical acceleration path has a first stop at the proximal end of the counter-support member and a second stop at the distal end of the horn-shaped member.

[0042] The proximal end of the acceleration path has a compressed air source connected via a first valve.

[0043] The projectile is specifically arranged inside the acceleration path. The projectile is designed and configured to accelerate from the first stop to the second stop via compressed air from a compressed air source, and from the second stop to the first stop via compressed air displaced and buffered in a storage chamber. A second valve may be arranged between the storage chamber and the acceleration path.

[0044] The acoustic oscillator, designed as a waveguide, is specially positioned at the far end of the horn-shaped component.

[0045] In this case, the proximal end of the acoustic oscillator is mechanically connected to a second stop in the acceleration path.

[0046] In this case, the stone crushing device is specifically designed and configured to detect the electrical signal of the piezoelectric element caused by the vibration generated at the first stop and / or the second stop due to the ejection, and the stone crushing device is used to regulate the compressed air of the compressed air source. Attached Figure Description

[0047] The present invention will now be explained in more detail based on exemplary embodiments, wherein,

[0048] Figure 1 A schematic diagram of a stone crushing device according to an embodiment of the present invention is shown; and

[0049] Figure 2 The diagram shows the measured values ​​of the electrical signal applied to the piezoelectric element over time during the execution of the method according to an embodiment of the invention.

[0050] Figure 3 A flowchart is shown for a method for determining the optimal frequency of the oscillating motion of a force-accelerated projectile in an in vivo lithotripsy device. Detailed Implementation

[0051] The stone crushing device 100 is used to perform a method for determining the optimal frequency of the oscillating motion of a projectile excited by compressed air. The stone crushing device 100 may be, for example, a handheld device having an acoustic oscillator attached to the distal end of the handheld device, wherein the acoustic oscillator has a flexible waveguide shaft.

[0052] The crushing equipment 100 has a piezoelectric element 130 arranged between a proximal counter-support 110 and a distal horn-shaped member 120. In this configuration, the piezoelectric element 130 is mechanically coupled to both the counter-support 110 and the horn-shaped member 120. The piezoelectric element 130 is subjected to an ultrasonic frequency of approximately 27 kHz by means of a signal generator (not shown).

[0053] Both the counter-support 110 and the piezoelectric element 130 have a hollow cylindrical shape. The horn-shaped member 120 has a rotationally symmetric shape, which has a cylindrical hollow portion along a central longitudinal axis. The proximal end of the horn-shaped member 120 has the same outer diameter as the piezoelectric element 130. Starting from the proximal end of the horn-shaped member 120, the outer diameter of the horn-shaped member initially remains constant within a predetermined path, and then gradually decreases to a diameter value slightly larger than the diameter of the cylindrical hollow portion inside the horn-shaped member 120.

[0054] In this configuration, the counter-support 110 functions as a reflector for the ultrasonic waves generated by the piezoelectric element 130. The shape of the horn-shaped member 120 and / or the counter-support 110 ensures that the generated lateral and rotational vibrations—as well as the generated longitudinal vibrations—are optimally guided to the distal end of the acoustic oscillator 170. Here, it is advantageous that the acoustic oscillator 170 and the horn-shaped member 120 comprise materials having substantially the same acoustic impedance.

[0055] A hollow cylindrical tube segment 140 is positioned inside the interior 122 of the counter-support member 110 and the horn-shaped member 120. The first end of the tube segment 140 has a first stop 142 located at the proximal end 112 of the counter-support member 110, and the second end of the tube segment 140 has a second stop 144 located at the distal end 124 of the horn-shaped member 120.

[0056] The proximal end 146 of pipe section 140 has a compressed air source 160 connected via a first valve 150. The first valve 150 has a check valve.

[0057] An elongated projectile 148 is arranged inside the interior 122 of the pipe section 140. This projectile can be accelerated from the first stop 142 to the second stop 144 by compressed air from the compressed air source 160. The projectile 148 can slide freely back and forth within the pipe section 140. The projectile 148 can be accelerated from the second stop 144 to the first stop 142 by compressed air that has been displaced by the projectile 148 and buffered in a storage chamber (not shown).

[0058] The projectile 148 has a cylindrical body made of very strong steel that is weakly magnetic. A retaining magnetic element (not shown) is arranged at the proximal end 146 of the tube section 140, which can attract the projectile 148 and keep it in a stationary state.

[0059] An acoustic oscillator 170, designed as a waveguide, is positioned at the distal end 124 of the horn-shaped member 120. In this configuration, the proximal end 172 of the acoustic oscillator 170 is mechanically coupled to a second stop 144, such that the impact of the projectile 148 on the second stop 144 optimally transmits the pulse of the projectile 148 to the acoustic oscillator 170. The diameter of the acoustic oscillator 170 is smaller than the diameter of the tube segment 140.

[0060] In the case of pneumatic lithotripsy, two systems can be used: an ultrasonic system with ultrasonic element 130 and a pneumatic system in which the projectile 148 is accelerated by compressed air from compressed air source 160. This is referred to as combined operation. Alternatively, the pneumatic system can also be operated without the ultrasonic system. In the latter case, the entire system can be calibrated when the signal generator is off, i.e., the limit value of the current intensity can be stored and used as a reference value in combined operation, where measurement is more difficult because the ultrasonic frequency represents an interference source.

[0061] In both cases, i.e., in combined operation or when only the pneumatic system is operated, the power signal is measured by a current clamp (not shown) at the connection line between the piezoelectric element 130 and the signal generator.

[0062] Since the ultrasonic vibration of the piezoelectric element 130 represents the interference source, the power signal measured by the current clamp is frequency filtered using an RLC circuit to filter out a small region around the ultrasonic frequency of approximately 27 kHz from the power signal. The width of the filtered frequency is preferably suitable for the interference signal.

[0063] The power signal after frequency filtering is converted into an analog rectified signal through a buffer circuit.

[0064] In the case of rectified signals, two thresholds can be identified: the first threshold corresponds to the impact of the projectile 148 on the first stop 142, and the second threshold corresponds to the impact of the projectile on the second stop 144.

[0065] The rectified signal is recorded by a microcontroller that controls and checks the entire evaluation. This microcontroller can perform reliability testing on the detected power signal to minimize incorrect measurements or measurement errors.

[0066] A method for determining the maximum frequency or corresponding optimal frequency of the oscillating motion of the projectile 148 excited by compressed air includes, according to a first step, repeatedly accelerating the projectile 148 from a first stop 142 at the proximal end of the pipe segment 140 to a second stop 144 at the distal end and from the second stop 144 back to the first stop 140 by compressed air.

[0067] In this configuration, the first valve 150 is used to introduce compressed air into the pipe section 140, causing the projectile 148 to accelerate from the first stop 142 to the second stop 144. The air displaced by the projectile 148 is buffered in a storage chamber, and after the first valve 150 is closed, the buffered compressed air is used to accelerate the projectile 148 from the second stop 144 to the first stop 142.

[0068] According to the second step of the method, the piezoelectric element 130 is excited with an ultrasonic frequency. For this purpose, a signal generator (not shown) operating at 27 kHz is connected to the piezoelectric element 130.

[0069] According to the third step of the method, the power signal of the piezoelectric element 130 caused by the vibration generated at the first stop 142 or the second stop 144 due to the projectile 148 is detected.

[0070] According to the fourth step of the method, the detected power signal is used to regulate the compressed air.

[0071] The power signal 180 has multiple exponentially decreasing parts modeled using sine or cosine functions, which are time-separated from each other. In this case, the first part 182 of the power signal 180 originates from the vibration of the projectile 148 at the second stop 144, while the second part 184 of the power signal 180 originates from the vibration of the first stop 142.

[0072] List of reference numerals

[0073] 100 stone crushing equipment

[0074] 110 Counter-support component

[0075] 112 Proximal end of the counter-support member

[0076] 120 Horn-shaped component

[0077] 122 Internal parts of the counter-support and flared member

[0078] 124 The distal end of the horn-shaped component

[0079] 130 piezoelectric element

[0080] 140 pipe section

[0081] 142 First stop in the acceleration path

[0082] 144 Second stop on the acceleration path

[0083] 146 Proximal end of the acceleration path

[0084] 148 projectiles

[0085] 150 First Valve

[0086] 160 Compressed Air Source

[0087] 170 acoustic oscillator

[0088] 172 Proximal end of acoustic oscillator

[0089] 180 power signal

[0090] The first part of the 182 power signal

[0091] The second part of the 184 power signal

[0092] 300 methods

[0093] 310 Method and Steps

[0094] 320 Method Steps

[0095] 330 Method and Steps.

Claims

1. A method for determining the optimal frequency of the oscillating motion of a force-accelerated projectile (148) in an in vivo lithotripsy device (100), the method comprising the steps of: - The projectile (148) is repeatedly accelerated from a first stop (142) at the proximal end of the acceleration path to a second stop (144) at the distal end and from the second stop (144) back to the first stop (142), wherein a piezoelectric element (130) is arranged between a counter-support (110) arranged at the proximal end and a horn-shaped member (120) arranged at the distal end, and the piezoelectric element (130) is mechanically connected to the counter-support (110) and the horn-shaped member. (120), and the horn-shaped member (120) has a distally arranged acoustic oscillator (170), wherein the acceleration path is arranged in the interior (122) of the anti-support member (110) and the horn-shaped member (120), and the first stop (142) is arranged at the proximal end (112) of the anti-support member (110), while the second stop (144) is arranged at the distal end (124) of the horn-shaped member (120). - Detect the electrical signal from the piezoelectric element (130) caused by the vibration at the first stop (142) and / or the second stop (144) due to the projectile (148); and - The detected electrical signal is used to control a medium that generates force and is used to accelerate the projectile (148) from the first stop (142) to the second stop (144) and from the second stop (144) to the first stop (142) in the acceleration path.

2. The method according to claim 1, characterized in that, The projectile (148) is accelerated by compressed air, wherein the medium is compressed air; the projectile (148) is accelerated by electromechanical impact force, wherein the medium is an electromagnetic field; or the projectile (148) is accelerated by mechanical equipment, wherein the medium is mechanical equipment.

3. The method according to claim 1 or 2, further comprising: - The piezoelectric element (130) is excited using ultrasonic frequencies.

4. The method according to claim 1 or 2, characterized in that, The acceleration path is achieved using a pipe segment (140), wherein the first end of the pipe segment (140) has a first stop (142), and the second end of the pipe segment (140) has a second stop (144).

5. The method according to claim 4, characterized in that, A first valve (150) is used to introduce compressed air into the pipe section (140) so that the projectile (148) is accelerated from the first stop (142) to the second stop (144), wherein the air displaced by the projectile (148) is buffered in a storage chamber, and after the first valve (150) is closed, the buffered compressed air is used to accelerate the projectile (148) from the second stop (144) to the first stop (142).

6. The method according to claim 1 or 2, characterized in that, The electrical signal of the piezoelectric element (130) is a power signal measured by a coil.

7. The method according to claim 6, further comprising: - Frequency filtering is performed on the power signal measured at the piezoelectric element (130); as well as - Rectify the frequency-filtered power signal.

8. The method according to claim 7, further comprising: - Determine at least one threshold for the rectified and frequency-filtered power signal, the at least one threshold corresponding to the impact of the projectile (148) on the first stop (142) or the second stop (144).

9. A stone crushing device (100), the stone crushing device (100) comprising: - A piezoelectric element (130) is arranged between a proximal counter-support (110) and a distal horn-shaped member (120), wherein the piezoelectric element (130) is mechanically connected to the counter-support (110) and the horn-shaped member (120), and a hollow cylindrical acceleration path is arranged inside (122) of the counter-support (110) and the horn-shaped member (120), the hollow cylindrical acceleration path having: a first stop (142) located at the proximal end (112) of the counter-support (110), and a second stop (144) located at the distal end (124) of the horn-shaped member (120), wherein the proximal end (142) of the acceleration path has: 6) The device has a compressed air source (160) connected via a first valve (150), or the crushing device (100) has a means for generating an electromagnetic field to apply an electromagnetic impact force to the projectile (148); and the projectile (148) is arranged inside the acceleration path (122), the projectile being designed and configured to accelerate from the first stop (142) to the second stop (144) by compressed air or electromagnetic impact force from the compressed air source (160), and to accelerate from the second stop (144) to the first stop (142) by compressed air or electromagnetic impact force displaced by the projectile (148) and buffered in the storage chamber. - Acoustic oscillator (170), the acoustic oscillator (170) is designed as a waveguide and the acoustic oscillator (170) is arranged at the distal end (124) of the horn-shaped member (120), wherein the proximal end (172) of the acoustic oscillator (170) is mechanically coupled to the second stop (144), and the stone crushing device (100) is designed and configured such that: an electrical signal from the piezoelectric element (130) caused by the vibration generated at the first stop (142) and / or the second stop (144) due to the projectile (148) can be detected and the electrical signal is used to control compressed air from the compressed air source (160) or to control electromagnetic impact force.

10. The stone crushing device (100) according to claim 9, wherein the stone crushing device (100) is used to perform the method according to claim 1 or 2.

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