Waveform control device for laser disintegration device, laser disintegration system, and laser disintegration method

Abstract

The laser disintegrating device is provided with a waveform control section that pulse-converts laser light excited from a laser light source and adjusts the repetition frequency of the pulse-converted laser light, and a fiber distal end (23a) that emits the laser light adjusted by the waveform control section toward a urinary stone (S) in a solution (W), the waveform control section adjusting the repetition frequency of the laser light to a frequency that generates a bubble (B) in the solution (W) and is synchronized with a period representing a dynamic including generation and disappearance of the bubble (B).

Description

Technical Field

[0001] Mutual references between related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 934,019, filed November 12, 2019, the entire contents of which are incorporated herein by reference.

[0003] This invention relates to a waveform control device, a laser crushing system, and a laser crushing method for laser crushing apparatus. Background Technology

[0004] Laser lithotripsy is a treatment method that removes stones located in the urinary tract (kidneys, ureters, or bladder) by irradiating them with a laser, breaking them down into smaller pieces. Laser lithotripsy utilizes the temperature rise caused by the absorption of laser energy by water within the stone, resulting in a steam explosion, or the thermochemical changes caused by the stone's own absorption of laser energy, to break the stones into pieces smaller than those that can be collected in a basket or expelled naturally. In laser lithotripsy, lasers with wavelengths that induce a temperature rise in either the water or the stone itself are typically used. When using laser lithotripsy on a living organism, it is crucial to efficiently deliver the laser to stones surrounded by fluid.

[0005] In recent years, various studies have been reported on improving the effectiveness of laser lithotripsy. The laser wavelengths that can induce a temperature rise in stones are, in principle, wavelengths that are absorbed by water or the solvents surrounding the stone. Therefore, it is difficult to make the laser propagate towards the stone without being absorbed by water or the solvents surrounding the stone, making it impossible to achieve a method that allows the laser to reach urinary tract stones without loss.

[0006] Patent Document 1 is a method for improving the transmittance of laser light in water. Patent Document 1 describes a technique as follows: Figure 19 As shown, by generating a small bubble using a first laser pulse at T1, and then setting an interval to generate a second laser pulse at T2 while the bubble is still inside, the transmittance is increased. In Patent Document 1, a Ho:YAG laser is used.

[0007] Non-Patent Literature 1 investigates the stone-breaking efficiency when a laser pulse is applied while the optical fiber is in contact with the stone. Non-Patent Literature 1 does not consider water, saline solution, aqueous solution, or organic solution present between the fiber tip and the stone. Non-Patent Literature 1 describes the efficiency of stone fragmentation under the same irradiation energy conditions when the stone is in contact with the optical fiber. Figure 20A Compared to using Figure 20BThe pulse train shown exhibits high lithotripsy efficiency. This is explained by the accumulation of energy within the lithotripsy itself and its release from the lithotripsy. In Non-Patent Document 1, a Tm fiber laser is used. Furthermore, in Non-Patent Document 1, laser pulses with a peak value of 70W, a pulse width of 500μs, and an energy of 35mJ are emitted from the front end of an optical fiber with a core diameter of 100μm.

[0008] Patent Document 2 is an international application published after U.S. Provisional Application No. 62 / 934,019, filed November 12, 2019, which asserts priority in this application. In Patent Document 2, as an example of insufficient laser fragmentation, a prior art laser fragmentation technique using first and second laser pulses with different pulse widths, similar to that in Patent Document 1, is cited in the background. In Patent Document 2, as... Figure 21 As shown, a laser pulse consisting of a low-output first pulse and a high-output second pulse is used. The interval between these first and second pulses is selected so that the bubbles generated by the first pulse reach the stone and disappear before the second pulse is irradiated.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: U.S. Patent Application Publication No. 2017 / 0354464

[0012] Patent Document 2: International Publication No. 2020 / 033121

[0013] Non-patent literature

[0014] Non-patent literature 1: NMFried et al., J. Biomed. Opt. 17 (2012) 028002 Summary of the Invention

[0015] The problem that the invention aims to solve

[0016] Existing laser fragmentation technology utilizes the interval after the first laser pulse to allow bubbles to naturally reach the stone being fragmented. Since only the second laser pulse contributes to fragmentation, the processing efficiency is low. Typically, in laser fragmentation, the longer the distance between the fiber tip and the stone, the more the laser is absorbed by the water, resulting in a weaker laser intensity reaching the stone. Furthermore, the bubbles generated in the liquid by the laser energy sometimes continuously change shape and size during laser fragmentation. Therefore, in conventional methods, it is easy for laser-generated bubbles to fail to reach the stone, leading to the wasteful use of excessive laser light or irradiation time.

[0017] The present invention was made in view of the above circumstances, and its object is to provide a laser crushing device, a laser crushing system, and a laser crushing method that can transfer laser energy to the object to be crushed without waste.

[0018] Methods for solving problems

[0019] To achieve the above objectives, the present invention provides the following means.

[0020] One aspect of the present invention is a laser breaking device comprising: a pulse generating unit that pulses a laser excited from a laser source; a repetition frequency adjusting unit that adjusts the repetition frequency of the laser pulsed by the pulse generating unit; and a laser emitting end that emits the laser adjusted by the repetition frequency adjusting unit toward a breaking object in a liquid, wherein the repetition frequency adjusting unit adjusts the repetition frequency to a frequency that generates bubbles in the liquid and is synchronized with a period representing the dynamics including the generation and disappearance of the bubbles.

[0021] According to this method, a pulsed laser, generated by a pulse generator, is emitted from the laser emission end and irradiates the object to be broken in the liquid, thereby breaking the object. The laser reaches the object to be broken by passing through bubbles generated in the liquid through the laser, which act as waveguides.

[0022] In this case, by adjusting the repetition frequency of the laser pulse train irradiating the object to be broken, the repetition frequency adjustment unit adjusts the frequency to a frequency that generates bubbles in the liquid and is synchronized with the period representing the dynamics of bubble generation and disappearance, thereby suppressing the waste of laser energy transmitted to the object to be broken.

[0023] The laser breaking device described above may also include a laser output changing unit that changes the output of the laser and reduces the output of the laser during the period when the bubble disappears.

[0024] If the bubble disappears, the laser cannot pass through. Therefore, the above structure can suppress the waste of laser energy transmitted to the broken object.

[0025] The laser breaking device described above can also be one in which the laser output changing unit turns the laser irradiation on and off synchronously with the repetition frequency.

[0026] A second aspect of the present invention is a laser fragmentation system comprising: a pulse generation unit that pulses a laser beam excited from a laser source; a repetition frequency adjustment unit that adjusts the repetition frequency of the laser pulsed by the pulse generation unit; a laser emission end that emits the laser beam adjusted by the repetition frequency adjustment unit toward a fragmentation object in a liquid; an imaging unit that images the fragmentation object; and a display unit that displays the fragmentation object imaged by the imaging unit, the display unit at least providing a visual indication of whether bubbles generated by the laser have reached the fragmentation object.

[0027] According to this method, a pulsed laser, generated by a pulse generation unit, is emitted from a laser emission end and irradiates a breakable object in a liquid, thereby breaking the object. Furthermore, the broken object, imaged by an image generation unit, is displayed on a display unit. The laser reaches the breakable object by passing through a bubble generated by the laser in the liquid, which acts as a waveguide.

[0028] In this case, the repetition frequency of the laser pulse train irradiating the object to be broken is adjusted by the repetition frequency adjustment unit to a frequency that generates bubbles in the liquid and is synchronized with the period representing the dynamics of bubble generation and disappearance, thereby suppressing the waste of laser energy delivered to the object to be broken. Furthermore, based on the screen displayed, the user can easily determine whether the bubbles generated by the laser have reached the object to be broken.

[0029] The laser fragmentation system described above may also include a computing unit that calculates the contact state between the bubble and the fragmentation object based on the fragmentation state of the fragmentation object as visualized by the imaging unit.

[0030] The laser fragmentation system described above can also be one in which the computing unit calculates the distance between the laser emission end and the fragmentation object based on the contact time between the bubble and the fragmentation object.

[0031] The laser fragmentation system described above can also be one in which the display unit displays the calculation results of the calculation unit.

[0032] According to this structure, users can easily determine the distance between the laser emission end and the object to be broken simply by visually confirming the display.

[0033] The third aspect of the present invention is a laser fragmentation method, comprising the following steps: irradiating a fragmentation object in a liquid with a laser pulse train having a certain period, and adjusting the repetition frequency of the pulse train to a frequency that generates bubbles in the liquid and is synchronized with a period representing the dynamics of the generation and disappearance of the bubbles.

[0034] According to this method, the object to be broken is broken by irradiating it with a laser pulse train of a certain period in a liquid. The laser reaches the object to be broken by passing through bubbles generated by the laser in the liquid as waveguides. Therefore, the repetition frequency of the laser pulse train irradiating the object to be broken is adjusted to a frequency that generates bubbles in the liquid and is synchronized with the period representing the dynamics of bubble generation and disappearance, thereby suppressing the waste of laser energy delivered to the object to be broken.

[0035] In the laser breaking method described above, the synchronization frequency is as follows: the laser is irradiated during a period overlapping with the generation period, wherein the generation period is from the time the bubble is generated in the liquid until it is about to disappear; the generation of the bubble using the laser is suppressed during a period overlapping with the disappearance period, wherein the disappearance period is from the time the bubble disappears immediately after the generation period until it can be generated again.

[0036] If the bubble disappears, the laser cannot pass through; therefore, if the laser is irradiated during the bubble's disappearance, the laser energy is wasted. Based on the above structure, the laser energy can be transferred to the object being broken without waste.

[0037] The laser ablation method described above can also suppress the formation of bubbles by reducing the laser output to a level that does not cause an increase in the temperature of the liquid.

[0038] The laser breaking method described above can also suppress the formation of bubbles by making the laser output zero.

[0039] In the laser fragmentation method described above, the repetition frequency can be between 1.7 kHz and 3.0 kHz. Alternatively, the repetition frequency can be between 1.7 kHz and 2.5 kHz. Or, it can be between 2.5 kHz and 3.0 kHz. Here, when lower laser power is required, a low repetition frequency range of 1.7 kHz to 2.0 kHz is selected; conversely, when higher laser power is required, a high repetition frequency range of 2.5 kHz to 3.0 kHz is selected. The user can switch between these ranges while observing the fragmentation process, thus enabling effective treatment.

[0040] The laser breaking method described above can also be used to irradiate the object being broken while maintaining the distance from the emitting end of the laser to the object being broken within a specified range.

[0041] This structure enables the laser to reach the object being broken efficiently.

[0042] The fourth aspect of the present invention is a laser fragmentation method, comprising the steps of: positioning a laser emitting portion toward a fragmentation object present in a liquid; irradiating the fragmentation object with pulsed laser light from the laser emitting portion, the laser light generating bubbles in the liquid and having a pulse train with a repetition frequency synchronized with a period representing the dynamics of the generation and disappearance of the bubbles.

[0043] According to this method, pulsed laser light is irradiated onto the object to be broken from a laser emission section positioned towards the object to be broken in the liquid, thereby breaking the object. The laser light reaches the object to be broken by passing through bubbles generated by the laser light in the liquid as waveguides. Therefore, the laser light irradiating the object to be broken has a pulse train with a repetition frequency synchronized with the period representing the dynamics of bubble generation and disappearance in the liquid, thereby suppressing the waste of laser energy delivered to the object to be broken.

[0044] The laser fragmentation method described above can also maintain the distance from the emission end of the laser emission section to the object to be fragmented within a specified range.

[0045] This structure enables the laser to reach the object being broken efficiently.

[0046] In the laser breaking method described above, the laser waveform can also be dynamically synchronized with the bubble by adjusting the time period during which the overlap between the light transmission waveform and the pulse train waveform composed of the laser pulse train increases. The light transmission waveform is obtained based on the change in light transmittance between the moment when the light transmittance begins to decrease sharply after the ratio of the laser reaching the breaking object reaches 100% and the moment when the light transmittance begins to increase again after the decrease.

[0047] The laser fragmentation method described above can also be a method in which the repetition frequency is switched between a low repetition frequency of 1.7 kHz to 2.5 kHz and a high repetition frequency of 2.5 kHz to 3.0 kHz.

[0048] In the laser fragmentation method described above, the duty cycle of the pulse train can be 45% to 55%.

[0049] Invention Effects

[0050] According to the present invention, the laser energy is able to reach the object to be broken without any waste. Attached Figure Description

[0051] Figure 1 This is a schematic structural diagram of a laser fragmentation system according to one embodiment of the present invention.

[0052] Figure 2 This is an explanation Figure 1 The graph shows the relationship between the laser irradiation intensity and the transmitted light intensity of the laser fragmentation device.

[0053] Figure 3A This is a diagram representing an example of a rectangular pulse train.

[0054] Figure 3B This is a diagram illustrating an example of a decaying triangular pulse.

[0055] Figure 3C This is a diagram illustrating an example of an enhanced triangular pulse.

[0056] Figure 3D This is a diagram illustrating an example of an M-shaped pulse.

[0057] Figure 4 This is a flowchart illustrating a laser fragmentation method according to one embodiment of the present invention.

[0058] Figure 5 This is a graph illustrating the relationship between laser irradiation intensity and transmitted light intensity when the laser repetition frequency is high.

[0059] Figure 6 This is a graph illustrating the relationship between laser irradiation intensity and transmitted light intensity when the laser repetition frequency is slow.

[0060] Figure 7 This is a schematic structural diagram of a laser fragmentation system according to a first variation of an embodiment of the present invention.

[0061] Figure 8 This is a schematic structural diagram of a laser fragmentation system according to a second variation of an embodiment of the present invention.

[0062] Figure 9 This is a schematic diagram of the measuring device used for transmittance measurement.

[0063] Figure 10A This is a diagram illustrating the output waveform of a laser.

[0064] Figure 10B It is a diagram illustrating the waveform of a laser beam passing through water.

[0065] Figure 11 This is a graph illustrating the correlation between the waveform of the laser beam after passing through water and the bubbles.

[0066] Figure 12 This is a schematic diagram of a measuring device used to measure changes in transmittance.

[0067] Figure 13 This is a graph illustrating an example of the pulse train frequency used in the measurement of changes in transmittance.

[0068] Figure 14 It is a graph illustrating the relationship between pulse train frequency and transmittance.

[0069] Figure 15A This is a diagram illustrating the relationship between the output waveform of a rectangular laser and the waveform transmitted through water.

[0070] Figure 15B This is a graph illustrating the relationship between the output waveform of a laser with a pulse train frequency of 1.67 kHz and the waveform transmitted through water.

[0071] Figure 15C This is a graph illustrating the relationship between the output waveform of a laser with a pulse train frequency of 2.27 kHz and the waveform transmitted through water.

[0072] Figure 15D This is a graph illustrating the relationship between the output waveform of a laser with a pulse train frequency of 6.25kHz and the waveform transmitted through water.

[0073] Figure 16 This is a diagram illustrating an example of the pulse width and spacing of a laser with a pulse train frequency of 2.27 kHz.

[0074] Figure 17 It is a graph illustrating the relationship between duty cycle and transmittance.

[0075] Figure 18A This is a graph showing an example of transmittance with a duty cycle of 20%.

[0076] Figure 18B This is a graph showing an example of transmittance at a duty cycle of 60%.

[0077] Figure 18C This is a graph showing an example of transmittance when the duty cycle is 80%.

[0078] Figure 18D This is a graph showing an example of transmittance at a duty cycle of 50%.

[0079] Figure 18E This is a graph showing an example of transmittance in the case of a rectangular wave.

[0080] Figure 19 This is a diagram illustrating Patent Document 1.

[0081] Figure 20A This is a diagram illustrating non-patent document 1.

[0082] Figure 20B This is another figure illustrating non-patent document 1.

[0083] Figure 21 This is a diagram illustrating Patent Document 2. Detailed Implementation

[0084] Hereinafter, a laser breaking apparatus, a laser breaking system, and a laser breaking method according to one embodiment of the present invention will be described with reference to the accompanying drawings.

[0085] like Figure 1 As shown, the laser fragmentation system 1 according to this embodiment includes a laser fragmentation device 3, a ureteroscope (imaging unit) 5 with a rigid or flexible endoscope, a display unit 7, an image information extraction unit 9, a transmittance calculation unit 11, a waveform setting unit 13, and a waveform information storage unit 15.

[0086] The laser crushing device 3 includes a laser source 21, an optical fiber (laser emission section) 23, an optical fiber connection section 25, and a waveform control section (pulse generation section, repetition frequency adjustment section, laser output change section) 27.

[0087] As the laser source 21, a thulium fiber laser (TLR-50 / 500-QCW-AC-Y16, IPG Photonics) can be used, for example. Alternatively, as the laser source 21, other lasers such as thulium fiber lasers, TLR-50 / 500-QCW, TLR-10, TLR-30, TLR-50, TLR-120, TLR-200, TLR-500, TLM-100, TLM-120, or TLM-200 can also be used. Furthermore, as the laser source 21, Tm:YAG lasers, Er:YAG lasers, Nd:YAG lasers, YFL, Cr:ZnSe / S, or cw Er fiber lasers can also be used.

[0088] The optical fiber 23 can be, for example, either a single-mode fiber or a multimode fiber, or a double-clad fiber. The optical fiber 23 is guided into the urinary tract P through the channel 5a of the ureteroscope 5. The urinary tract P is filled with a solution W such as urine, water, or saline. The optical fiber 23 has a distal end (laser emission end) 23a from which the guided laser light is emitted. Furthermore, the optical fiber 23 can emit a targeting beam from the distal end 23a.

[0089] The fiber optic connector 25 reads information from the connected fiber optic cable 23. Furthermore, the fiber optic connector 25 transmits fiber identification information, including the core diameter and NA characteristics of the fiber optic cable 23, to the waveform control unit 27.

[0090] The ureteroscope 5 observes the morphology of the urinary tract stone (fragmented object) S. The ureteroscope 5 is equipped with a function to generate a ureteroscopic image of the urinary tract stone S. The image generated by the ureteroscope 5 is displayed on the display unit 7. Based on the ureteroscopic image displayed on the display unit 7, the user can confirm the bubble B generated by the laser (reference). Figure 2Whether the urinary tract stone S has been reached. Furthermore, the user can determine this by observing the ureteroscopic image, thereby setting the waveform of the laser through the waveform setting unit 13.

[0091] The image information extraction unit 9 extracts the intensity of the scattered light emitted from the distal end 23a of the optical fiber based on the ureteroscope image generated by the ureteroscope 5.

[0092] The transmittance calculation unit 11 calculates the transmittance of the aiming light based on the intensity of the scattered light extracted by the image information extraction unit 9. Furthermore, the transmittance calculation unit 11 generates waveform control information based on the calculated transmittance and transmits the generated waveform control information to the waveform control unit 27.

[0093] The waveform setting unit 13 sets the waveform of the laser selected by the user. The waveform setting unit 13 transmits waveform information representing the set waveform to the waveform control unit 27.

[0094] The waveform information storage unit 15 stores wavelength information of the laser light source 21 and waveform information for generating appropriate waveforms based on the wavelength information.

[0095] The waveform control unit 27 obtains desired waveform information from the waveform information storage unit 15 based on at least one of the fiber identification information sent from the fiber connection unit 25, the waveform information sent from the waveform setting unit 13, and the waveform control information sent from the transmittance calculation unit 11. Furthermore, the waveform control unit 27 controls the excitation of the laser source 21 based on the obtained waveform information. The processing of the image information extraction unit 9, the transmittance calculation unit 11, and the waveform control unit 27 can also be performed by at least one processor including hardware.

[0096] The waveform control unit 27, for example, shapes the laser excited from the laser source 21 into pulses of a frequency such that bubbles B are generated when the laser propagates in the liquid, and the intensity of the laser and the excitation frequency change synchronously with the generation and elimination (disappearance) of the generated bubbles.

[0097] Specifically, such as Figure 2 As shown, the waveform control unit 27 adjusts to a pulse train with a frequency corresponding to the frequency at which bubbles B are generated in solution W by the laser. The frequency of this pulse train is such that the laser is irradiated during a period overlapping with the generation period, which is the period from the generation of bubble B in solution W by the laser until bubble B is about to disappear. During a period overlapping with the disappearance period, the laser output is reduced, which is the period from the disappearance of bubble B immediately following the generation period until bubble B can be generated again. In this embodiment, the laser output is set to zero during the period overlapping with the disappearance period. By stopping the laser, the generation of bubble B is suppressed.

[0098] The shaped pulse can be, for example, Figure 3A The rectangular pulse train shown Figure 3B , 3C The pulse shape can be a 3D-dissipated triangular pulse, an enhanced triangular pulse, an M-shaped pulse, or a combination thereof. The repetition frequency is preferably 1.7 kHz or higher and 3.0 kHz or lower. For example, the repetition frequency can be 1.7 kHz or higher and 2.0 kHz or lower, or 2.5 kHz or higher and 3.0 kHz or lower. The pulse shape can be generated, for example, using a function generator (WF1974, NF). For lasers requiring lower power, a frequency of 1.7 kHz or higher and 2.0 kHz is selected; for lasers requiring higher power, a frequency of 2.5 kHz or higher and 3.0 kHz or lower is selected.

[0099] Next, the laser fragmentation method of this embodiment is, for example, as follows: Figure 4 The flowchart shows the following steps: step S1, exciting a laser; step S2, irradiating the excited laser onto a urinary calculus S in solution W; step S3, adjusting the repetition frequency of the pulse train to a frequency that generates bubbles B in solution W and is synchronized with a period representing the dynamics of the generation and disappearance of bubbles B; and step S4, irradiating the urinary calculus S with a laser pulse train having a certain period.

[0100] Step S3 is preferably performed during the light guiding process from when the laser is excited from the laser source 21 (step S1) to when the laser is irradiated from the front end of the optical fiber (step S4).

[0101] Next, the function of the laser fragmentation system 1 and the laser fragmentation method involved in this embodiment will be explained.

[0102] When breaking up urinary calculi S in solution W using the laser fragmentation system 1 and laser fragmentation method according to this embodiment, after connecting the optical fiber 23 to the optical fiber connector 25, the distal end 23a of the optical fiber is positioned towards the urinary calculi S. Furthermore, the distance from the distal end 23a of the optical fiber to the urinary calculi S is maintained within a predetermined range. Optical fiber identification information is transmitted from the optical fiber connector 25 to the waveform control unit 27.

[0103] For example, in order to keep the distal end 23 of the optical fiber within 3 mm of the urinary tract stone S, if it exceeds 3 mm, the user is alerted that it has deviated from the prescribed range based on information such as the image displayed on the display unit 7. The user then moves the laser fragmentation device 3 within the urinary tract until it reaches the prescribed range.

[0104] On the other hand, during the period when the laser fragmentation device 3 moves within a prescribed range through user operation, the display unit 7 indicates whether it is within the appropriate range, or indicates nothing at all. Similarly, if it is within the prescribed range, even if the patient moves or the laser fragmentation device 3 moves relative to the patient due to physical activities such as breathing, no information will be displayed on the display unit 7. The distance from the distal end 23 of the optical fiber to the proximal end of the urinary tract stone S can be measured using a laser, for example, using the Time of Flight (ToF) method disclosed in International Publication No. 2020 / 021590.

[0105] Next, a targeting beam is emitted from the distal end 23a of the optical fiber toward the urinary tract stone S. Additionally, a laser beam is generated from the laser source 21. The excited laser beam is incident on the optical fiber 23 via the optical fiber connector 25. The laser beam, guided by the optical fiber 23, is emitted from the distal end 23a of the optical fiber toward the urinary tract stone S.

[0106] Next, an image of the urinary tract stone S is generated using the ureteroscope 5, and the generated image is displayed on the display unit 7. Based on the ureteroscope image displayed on the display unit 7, the user sets the laser waveform using the waveform setting unit 13. The waveform setting unit 13 sets the laser waveform selected by the user. Waveform information representing the set waveform is transmitted from the waveform setting unit 13 to the waveform control unit 27.

[0107] Furthermore, the image information extraction unit 9 extracts the intensity of the scattered light from the aiming beam in the urinary tract stone S based on the generated ureteroscopic image. The transmittance calculation unit 11 calculates the transmittance of the aiming beam based on the extracted scattered light intensity and generates waveform control information based on the calculated transmittance. The generated waveform control information is then transmitted to the waveform control unit 27.

[0108] The waveform control unit 27 obtains desired waveform information from the waveform information storage unit 15 based on at least one of the fiber identification information from the fiber connection unit 25, the waveform information from the waveform setting unit 13, and the waveform control information from the transmittance calculation unit 11, and controls the excitation of the laser source 21 based on the obtained waveform information.

[0109] Specifically, the laser emitted from the laser source 21 is adjusted to a pulse train at a frequency that generates bubble B in solution W, and the frequency of the pulse train is such that the laser is irradiated during a period that overlaps with the generation period, wherein the generation period is from the time bubble B is generated in solution W using the laser until bubble B is about to disappear, and the laser irradiation is stopped during a period that overlaps with the disappearance period, wherein the disappearance period is from the time bubble B disappears immediately after the generation period until it can be generated again.

[0110] Here, the waveform control unit 27 compares the transmitted waveform with the waveform of the laser excited from the laser source 21. The transmitted waveform is obtained from the transmittance calculation unit 11 by calculating the start time when the transmittance begins to decrease sharply after reaching approximately 100% and the start time when the transmittance begins to increase after decreasing. Furthermore, the laser waveform is made consistent over a relatively long period of time, maximizing the overlap of these waveforms. This adjustment, which dynamically synchronizes the laser with the bubble at an arbitrary repetition frequency, results in the longest possible period of high transmittance during laser irradiation. Preferably, this adjustment of the laser by the waveform control unit 27 is performed continuously until the urinary calculus S to be broken down becomes sufficiently small.

[0111] Thus, for example, such as Figure 2 As shown, by emitting a laser from the far end 23a of the optical fiber, bubble B is generated at the far end 23a of the optical fiber. Figure 2 (a) state). Then, through the growth of bubble B, when bubble B connects the distal end of the optical fiber 23a and the urinary tract stone S ( Figure 2 (b) state), the laser emitted from the distal end 23a of the optical fiber passes through bubble B and reaches the urinary tract stone S ( Figure 2 (c) state).

[0112] Next, when bubble B is cooled by solution W and begins to contract, the laser irradiation is temporarily stopped in sync with the contraction of bubble B. Figure 2 (d) state).

[0113] After bubble B disappears, laser light is emitted again from the distal end 23a of the optical fiber. Then, through the growth of bubble B, when bubble B connects the distal end 23a of the optical fiber to the urinary tract stone S, the laser light passes through bubble B and irradiates the urinary tract stone S again.

[0114] Similarly, the laser is repeatedly turned on and off in accordance with the growth and disappearance cycle of bubble B.

[0115] Furthermore, by repeatedly irradiating the urinary tract stone S with laser, the energy of the laser is absorbed by the water in the urinary tract stone S, causing the temperature to rise. This temperature rise is accompanied by water vapor explosion or thermochemical changes caused by the urinary tract stone S absorbing the laser energy, which causes the urinary tract stone S to break up.

[0116] As explained above, according to the laser fragmentation apparatus 3, laser fragmentation system 1, and laser fragmentation method of this embodiment, the repetition frequency of the laser irradiating the urinary tract stone S is adjusted by the waveform control unit 27 to a frequency that generates bubble B in solution W and irradiates the laser during the generation period from when bubble B is generated in solution W until it is about to disappear, and stops the laser during the disappearance period from when bubble B disappears until it can be regenerated. In this way, the energy of the laser can be transferred to the urinary tract stone S without waste.

[0117] As a comparative example of this embodiment, a case where the laser repetition frequency is faster than the period representing the dynamics of bubble B's generation and disappearance will be described. In this case, for example, as... Figure 5 As shown, laser irradiation is stopped during the period when bubble B connects the distal end 23a of the optical fiber to the urinary tract stone S. Therefore, the period during which laser energy can be fully utilized to transfer to the urinary tract stone S is not fully utilized, resulting in reduced treatment efficiency.

[0118] Furthermore, as a comparative example of this embodiment, a case where the laser repetition frequency is slower than the period representing the dynamics of bubble B's generation and disappearance will be described. In this case, for example, as... Figure 6 As shown, laser light continues to be emitted while bubble B begins to leave the distal end 23a of the optical fiber due to contraction. Therefore, the laser continues to be emitted before reaching the urinary tract stone S, thus wasting laser energy.

[0119] Furthermore, in this embodiment, the transmittance of the aiming light and the intensity of the scattered light change when bubble B is generated and when it disappears. Therefore, the transmittance is calculated based on the correlation between the intensity of the scattered light and the transmittance. Alternatively, the scattered light from the endoscope's illumination light can also be used.

[0120] Alternatively, the optical sensor can be positioned at the laser irradiation location via an access sleeve (not shown) to directly monitor the intensity of the transmitted laser light.

[0121] This embodiment can be modified into the following structures.

[0122] As a first variation example, for example, such as Figure 7 As shown, the laser breaking system 1 may also include a scattered light separation unit 31 such as a dichroic mirror and a detector 33. Alternatively, the laser breaking system 1 may not include an image information extraction unit 9. The scattered light separation unit 31 is disposed in the optical path of the laser between the laser source 21 and the optical fiber connection unit 25.

[0123] In this modified example, the scattered light from the aiming beam in the urinary tract stone S is focused by the optical fiber 23 and then returns in the opposite direction in the laser's optical path. Therefore, it is also possible that the scattered light returning in the opposite direction is separated from the laser beam by the scattered light separation unit 31, and the intensity of the scattered light separated by the scattered light separation unit 31 is detected by the detector 33. Furthermore, the transmittance calculation unit 11 can calculate the transmittance of the aiming beam based on the intensity of the scattered light detected by the detector 33.

[0124] As a second variation, for example, such as Figure 8 As shown, the laser fragmentation system 1 may also include a stone morphology recognition unit (computation unit) 35 instead of the transmittance calculation unit 11. Furthermore, the image information extraction unit 9 may extract the stone morphology based on ureteroscopy images.

[0125] In this modified example, the stone morphology recognition unit 35 can also generate waveform control information by recognizing the morphology of the urinary tract stone S extracted by the image information extraction unit 9. Furthermore, the waveform control information generated by the stone morphology recognition unit 35 can also be transmitted to the waveform control unit 27.

[0126] In this modified example, the stone morphology recognition unit 35 can also calculate the contact state between the air bubble B and the urinary tract stone S based on the morphology of the urinary tract stone S extracted by the image information extraction unit 9, such as its fragmentation state. Examples of contact states include whether the air bubble B and the urinary tract stone S are in contact, and the contact time if they are in contact.

[0127] Furthermore, the stone morphology recognition unit 35 can also calculate the distance between the distal end 23a of the optical fiber and the urinary tract stone S based on the contact time between the bubble B and the urinary tract stone S. The contact state between the bubble B and the urinary tract stone S and the distance between the distal end 23a of the optical fiber and the urinary tract stone S calculated by the stone morphology recognition unit 35 can also be displayed on the display unit 7.

[0128] In the above embodiments and modifications, laser irradiation is stopped during the disappearance of bubble B. Alternatively, laser irradiation may not be stopped, but the laser output may be reduced to an amount that does not cause a temperature rise in solution W. Even in this case, energy waste of the laser can be suppressed. Here, the amount of laser that does not cause a temperature rise means, for example, a small output that does not produce bubble formation during the bubble disappearance period in order to prevent excessive temperature drop due to the infusion of liquid such as water between the fiber tip and the stone, thus preventing thermal shock. The small output that can be applied during the bubble disappearance period can be less than 1 / 10 of the laser output during bubble formation, preferably less than 1 / 100.

[0129] In the above embodiments and modifications, an example applied to a urinary catheter was shown, but it can also be an endoscope that obtains images from any organ in the body, such as the bile duct or kidney, from which stones can form. Preferably, laser lithotripsy is performed while observing the images, corresponding to the composition of the stones formed in each organ. Regarding the use of an endoscope in a laser lithotripsy device, refer to international application PCT / JP2019 / 007928 entitled "Lipotripsy Device and Lithotripsy System". According to the distance measurement technology described in that international application, even in the presence of bubbles generated and moving between the laser tip and the stone, the distance to the stone can be accurately determined.

[0130] Example

[0131] Next, embodiments of the laser crushing apparatus, laser crushing system, and laser crushing method described in the above embodiments will be explained.

[0132] (Laser fragmentation method)

[0133] In the treatment of urinary tract stones, the current gold standard is laser lithotripsy (fURS or fTUL). Laser lithotripsy works by irradiating the stone (the object to be broken) with a laser, causing the stone to absorb the laser and breaking it up by raising its temperature.

[0134] In this method, efficiently delivering light to the stones is crucial. Ho:YAG lasers have been previously used in fURS (further fragmentation), but high-output holmium-YAG (Ho:YAG) lasers for lithotripsy are very large due to the need for water cooling. On the other hand, Tm fiber lasers (TFLs) that operate via air cooling have attracted attention. TFLs have been reported to offer better lithotripsy efficiency compared to Ho:YAG lasers.

[0135] Ho:YAG is excited at 2100 nm, and TFL at 1940 nm (typical), but these wavelengths are strongly absorbed by water. Therefore, the distance the laser can reach is limited when using Ho:YAG and TFL for in vivo therapy.

[0136] (Transmittance measurement)

[0137] pass Figure 9 The measuring device 41 shown uses a photodiode (PD) 45 to measure the output waveform of the laser 43 and the waveform of the laser after passing through water. Figure 9 In the attached figure, reference numeral 44 indicates an optical fiber, and reference numeral 47 indicates an oscilloscope. The measurement results are shown in... Figure 10A and Figure 10B . Figure 10A This represents the output waveform of the laser. Figure 10B This represents the waveform of the laser beam after it passes through water. Figure 10A and Figure 10BIn the diagram, the vertical axis represents intensity, and the horizontal axis represents time.

[0138] When the output waveform of a rectangular wave is measured after passing through water, the intensity changes in a roughly regular manner. The correlation between this transmitted waveform and bubbles captured by a high-speed camera (Fast Cam 49) is investigated. The results are presented below. Figure 11 .exist Figure 11 The upper part shows that Figure 10B The waveform after cutting out during the initial period of irradiation. Figure 11 In (a) to (f), the shape of the bubble at each moment of the waveform shown by the dashed line is shown.

[0139] (Bubble observation)

[0140] like Figure 9 As shown, a high-speed camera (Fast Cam) 49 was used to capture and record the bubble formation process of each pulse. The shooting speed was 100,000 frames per second.

[0141] A schematic structural diagram of a measuring device used for transmittance measurement. Figure 9 In this process, the shape of the bubbles was also measured using measuring device 41. The photographic area was illuminated from the back of the unit equipped with optical fiber 44 by Kola illumination using a halogen lamp (not shown) as the light source. The bubbles appeared as shadows in the images captured by the camera. The observed bubble images were recorded in... Figure 11 (a)~(f).

[0142] exist Figure 11 In the time region shown in (a), bubbles begin to form immediately after the laser is output. However, in Figure 11 In the time region shown in (b), the bubble is in the middle of its formation and has not yet reached the bottom quartz substrate Q, therefore the transmitted light intensity remains 0. Figure 11 In the time region shown in (c), light first passes through the bubble as it grows further and comes into contact with the quartz substrate Q.

[0143] exist Figure 11 In the time region shown in (d), light transmission is interrupted when the bubble is cooled by the surrounding water and begins to contract. According to Figure 11 As shown in (e), in the time region where light does not transmit, the bubble separates from the tip of fiber 44. Figure 11 In the time region shown in (f), light is transmitted again when the bubble regrows and reaches the quartz substrate Q.

[0144] like Figure 11 As shown, there is a correlation between the intensity of transmitted light and the size of the bubble. Furthermore, it is known that... Figure 11The time range in (e) where the bubbles disappear represents the dead zone where the irradiated energy did not reach the stone. Figure 11 The illumination in that time region, as shown in (e), becomes wasted.

[0145] This embodiment provides a method for efficiently supplying energy to kidney stones by stopping the laser in sync with the disappearance of bubbles. In other words, it provides a method for efficiently supplying energy to kidney stones by modulating the laser intensity in sync with the formation and disappearance of bubbles.

[0146] (Principle Verification)

[0147] To verify the effect of synchronizing bubble generation with pulse control, in Figure 12 In the measuring device 41 shown, the distance from the tip of the optical fiber 44 to the quartz substrate Q is set to 1.0 mm, 1.5 mm, and 2.0 mm. Furthermore, in each distance, such as... Figure 13 As shown, the transmittance of the laser is measured by changing the pulse train frequency (pulse sequence frequency, PT frequency).

[0148] The water thickness is varied by changing the distance from the tip of optical fiber 44 to the quartz substrate Q. At each distance and frequency, the transmitted light intensity is divided by the intensity at which the water thickness is zero, thereby calculating the laser transmittance. The calculation results are shown below. Figure 14 .

[0149] exist Figure 14 In the diagram, circles (〇), triangles (▲), and quadrilaterals (□) represent the transmittance when the water thickness is 1.0 mm, 1.5 mm, and 2.0 mm, respectively. Additionally, the vertical axis represents the laser transmittance, and the horizontal axis represents the pulse train frequency (PTfrequency). For convenience, the transmittance of the rectangular wave is plotted at a frequency of 0.

[0150] At various water thicknesses, a frequency dependence was observed in the transmittance, revealing frequencies where the transmittance reaches a maximum, indicated by hollow arrows. Figure 14 In the diagram, the transmittance of the rectangular wave is represented by the dashed line, with the portion above the dashed line corresponding to the frequency at which the transmittance increases due to the pulse train. The maximum frequency is almost independent of the water thickness. Therefore, by setting the pulse train frequency to the range of 1.68 kHz to 3 kHz shown in the diagram, an increase in transmittance can be achieved.

[0151] Figure 15A , Figure 15B , Figure 15C as well as Figure 15D The output waveforms (CH1) and water-transmitting waveforms (CH2) are shown for rectangular wave, pulse train frequencies of 1.67 kHz, 2.27 kHz, and 6.25 kHz, respectively. Figure 15BIn the time region indicated by the hollow arrow, although the output waveforms are continuous, attenuation of the transmitted water waveform is observed. This is consistent with... Figure 15A The situation is similar to that of rectangular waves, where the irradiation energy in that time region is wasted as it does not reach the stone. On the other hand, in Figure 15D In this case, because the output waveform is interrupted before the bubble grows, the intensity of the transmitted waveform will not become sufficiently large.

[0152] When transmittance becomes extremely high Figure 15C In this process, the output waveform is attenuated synchronously with the observed attenuation of the transmitted waveform, i.e., the disappearance of the bubbles. Thus, it can be seen that by changing the pulsed state of the laser according to the morphology of the bubbles generated in the liquid using the laser energy, the transmittance of the laser irradiating the stone can be adjusted. Therefore, in particular, by controlling the waveform of the pulse sequence synchronously with the disappearance of the bubbles, the laser can reach the stone efficiently.

[0153] At low pulse frequencies, i.e., with long pulse irradiation and long pulse pause times, the bubble transitions from expansion to contraction. During this contraction period, the energy of the irradiated laser is absorbed by the water, resulting in low transmittance. Figure 15A In this case, the pulse frequency is 1.67 kHz. At higher pulse frequencies, i.e., with short pulse irradiation and irradiation times, the laser irradiates the bubbles before they have fully grown or completely disappeared. Therefore, incomplete bubbles are generated, resulting in lower transmittance. Figure 15D In this case, the pulse frequency is 6.25kHz.

[0154] Therefore, by irradiating the water with laser while the bubbles generated by the laser irradiation are expanding, stopping or reducing the laser irradiation when the bubbles change from expansion to contraction, and starting or increasing the laser irradiation after the bubbles have completely disappeared, the transmittance can be improved by repeating the above operation.

[0155] Specifically, such as Figure 14 As shown, by setting the pulse train frequency to 1.68–3.0 kHz, the transmittance can be improved.

[0156] Figures 9 to 15D Measurements were performed under conditions of a laser peak power of 500W, a fiber core diameter of 272μm, an fiber NA of 0.65, and an output NA of 0.1. The frequency of the optimal pulse sequence can be optimized based on these conditions. The fiber used here is HLFDBX0270c, manufactured by Dornier MedTech.

[0157] in addition, Figures 9 to 15DThis represents the duty ratio of the pulse sequence, i.e., the ratio of pulse generation to interval, which is 50%. 1.67kHz corresponds to a pulse width of 300μs and an interval of 300μs. The extremely high 2.27kHz corresponds to a pulse width of 220μs and an interval of 220μs. 3kHz corresponds to a pulse width of 167μs and an interval of 167μs. The interval can also be changed if the next pulse is generated synchronously with the pulse generation at the optimal timing. Changing the interval while keeping the pulse width the same will naturally cause the frequency range to deviate from the above range.

[0158] Furthermore, to increase the spatial density of the laser, the energy density and divergence angle of the laser will differ when a focusing optical system such as a convex lens or a spherical lens is installed at the front end of the optical fiber. Therefore, the modulation frequency of the pulse sequence can be optimized based on the laser's energy density and divergence angle to optimize the pulse width and spacing.

[0159] Figure 16 and Figure 17 This represents the transmittance measured by varying the duty cycle at 2.27 kHz (pulse and interval period 440 μs). In this case, it exhibits a very high transmittance at a duty cycle of 50%, showing a higher transmittance than the rectangular wave.

[0160] Figure 18A , Figure 18B , Figure 18C , Figure 18D as well as Figure 18E The output waveform (CH1) and the water-permeable waveform (CH2) are shown for each duty cycle.

[0161] like Figure 18A As shown, because the pulse width is narrow at a duty cycle of 20%, the pulse stops before the bubbles are fully formed. Therefore, the transmittance deteriorates. Conversely, as... Figure 18B As shown, when the duty cycle is increased (60%), the bubble disappears during the pulse duration, resulting in wasted irradiation. Furthermore, as... Figure 18C As shown, even with a duty cycle of 80%, laser output continues during the period when the bubble disappears, thus wasting output during this period. On the other hand, as... Figure 18D As shown, with a duty cycle of 50%, the pulse stops synchronously with the disappearance of the bubble, thus increasing the transmittance. Figure 18E This represents the output waveform in the case of a rectangular wave. In summary, it was revealed that, at a duty cycle of 40% to 60%, more efficient irradiation can be achieved compared to the conventional method of waiting for the bubbles to disappear naturally at intervals. The most efficient irradiation is preferably achieved by setting the duty cycle to 45% to 55%.

[0162] Example

[0163] In this embodiment, a lithotripsy laser system is provided, characterized in that, in a treatment device that guides TFL light for lithotripsy from the proximal end to the distal end through an optical fiber and irradiates the stone with the guided laser light through urine, water, saline, any aqueous solution or organic solution, a TFL pulse train is generated, and the frequency of the pulse train used to control the laser excitation synchronously with the generation and disappearance of bubbles is set to 1.68 to 3.0 kHz.

[0164] According to this embodiment, by setting the pulse train frequency regardless of the distance from the far end of the optical fiber to the stone, the intensity of transmitted light can be increased for a typical rectangular wave, thereby increasing the light intensity reaching the stone.

[0165] The excitation intensity and frequency of the TFL (Thunder Flask) are controlled by a control signal generator that generates electrical pulses of varying intensity and frequency using a function generator, etc. By exciting the TFL based on the control signal, the desired pulse train output is obtained. The TFL pulse train uses optical fiber to guide light from near to far, irradiating the stone through an aqueous or organic solution. Because the pulse train frequency is set independently of the distance to the stone, the energy reaching the stone can be increased, thereby improving the stone fragmentation efficiency.

[0166] [First Variation]

[0167] In the above embodiments, the pulse shape is as follows: Figure 3A As shown, the pulse control unit generates a pulse shape that is rectangular in shape and forms a pulse train. Alternatively, it can be replaced with pulses of the shape shown below, or a combination of pulses of the shape shown below and rectangular pulses.

[0168] For example, such as Figure 3B As shown, it can also be a pulse with a decaying triangle that changes from a strong intensity state to a weak intensity state. Additionally, as... Figure 3C As shown, it can also be a pulse with an enhanced triangle that changes from a weak state to a strong state.

[0169] Alternatively, effects based on the individual pulse shapes can be generated by alternately exciting pulses with a decaying triangular shape and pulses with an enhancing triangular shape.

[0170] Alternatively, a pulse shape can be created by combining pulses with a decaying triangular shape and pulses with an enhancing triangular shape, such as... Figure 3D As shown, by forming an M-shaped shape, an effect based on the pulse shape of both parties is generated simultaneously.

[0171] Furthermore, the pulse shapes described above can be varied depending on the size, dimensions, and distance of the stone being broken, thereby efficiently breaking the stone. For example, when the stone is not floating in the urethra before or during breaking, a rectangular pulse can be used. Conversely, when the stone is floating in the urinary tract, an M-shaped or reinforced triangular pulse can be used.

[0172] By using pulses of this shape, the shape of the bubbles generated by laser irradiation changes, and the water flow caused by the bubbles changes. This can suppress the movement of stones or guide their position along the laser irradiation axis.

[0173] [Second variation]

[0174] In this embodiment, the output wavelength of the TFL is assumed to be 1940 nm, but there are cases where the excitation wavelength varies depending on the TFL housing. In this case, the absorption intensity of the water changes, thus causing differences in the bubble formation and disappearance times. Therefore, as a second variation, a step of optimizing the pulse train frequency according to the TFL excitation wavelength may also be included.

[0175] Furthermore, in order to break up the stone by efficiently injecting energy into the stone itself and raising its temperature, it is preferable to select a wavelength with high absorption intensity of the stone's components, especially water. Therefore, it is preferable to use a laser excited at the absorption wavelengths of water (around 2 μm, 3 μm, and 1.5 μm ±400 nm).

[0176] In this case, similar to the TFL case, the laser is absorbed by the water, thus generating bubbles through laser irradiation. Therefore, even with these wavelengths, transmittance can be increased by modulating the laser intensity in sync with the timing of bubble formation and dissipation. The modulation frequency depends on the water's absorption intensity, so a step of selecting an appropriate frequency based on the wavelength may also be included.

[0177] Furthermore, it may also include a step of optimizing the pulse train frequency by identifying the housing information of the TFL.

[0178] Furthermore, the bubble formation and disappearance times depend on the temporal and spatial density of the laser at the far end of the optical fiber. Therefore, if the fiber core diameter and divergence angle (or NA) change, the optimal frequency of the pulse train will also change. In this embodiment, a step of setting the pulse train frequency based on the diameter of the optical fiber used may also be included.

[0179] Therefore, the method may also include arbitrarily inputting the characteristic values ​​of the optical fiber used in this embodiment and setting the pulse train frequency based on the input optical fiber characteristic values. Alternatively, it may include automatically identifying the optical fiber through optical fiber installation, thereby setting the pulse train frequency based on the obtained optical fiber characteristic values.

[0180] Similarly, as described above, the temporal and spatial density of the laser at the far end of the fiber also changes according to the excitation peak of the TFL, i.e., the energy intensity at each moment. Therefore, the step of setting the pulse train frequency may also be included based on the excitation peak of the TFL arbitrarily set by the user, or the excitation peak of the TFL that can be selected as a setting item of the housing.

[0181] Furthermore, while urinary tract stones were used as an example for fragmentation in this embodiment and its variations, the effect of the pulse sequence is not limited to the treatment of urinary tract stones; it can also be achieved in the treatment of bile duct stones. Additionally, improving laser transmittance is useful in surgeries using lasers in water, aqueous solutions, or organic solutions. Therefore, this embodiment is not limited to urinary tract stones and can be applied to the treatment of any biological tissue. That is, the above-described embodiments and examples are not limited to fragmentation targets of stones and can be applied to lesions that can be fragmented by laser. Moreover, the fragmentation target is not limited to substances produced within the body, but can also include unwanted substances that can be fragmented by laser when approached with an endoscope.

[0182] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the specific structure is not limited to these embodiments, and design changes that do not depart from the spirit of the present invention are also included. For example, the present invention is not limited to the above embodiments and modifications, but can also be applied to embodiments in appropriate combinations of these embodiments and modifications, and is not particularly limited.

[0183] Label Explanation

[0184] 1. Laser fragmentation system

[0185] 3. Laser fragmentation device

[0186] 5. Ureteroscopy (Imaging Section)

[0187] 7 Display Section

[0188] 23. Optical fiber (laser emission section)

[0189] 23a Fiber optic distal end (laser emission end)

[0190] 27. Waveform Control Unit (Pulse Generation Unit, Repetition Frequency Adjustment Unit, Laser Output Modification Unit)

[0191] 35. Stone Morphology Recognition Unit (Computation Unit)

[0192] B bubbles

[0193] S Urinary tract stones (object to be crushed)

Claims

1. A waveform control device for a laser crushing apparatus, comprising: A pulse generation unit that pulses the laser beam; and The laser output modification unit modifies the output of the pulsed laser. The laser output modification unit continuously emits laser light before the bubble generated from the laser emission end reaches the object to be broken. After the bubble generated from the laser emission end reaches the object to be broken, during the period when there is a bubble between the laser emission end and the object to be broken and the bubble does not connect the laser emission end and the object to be broken, the laser output change unit reduces or shuts down the laser output in sync with the contraction of the bubble.

2. The waveform control device for the laser fragmentation apparatus according to claim 1, wherein, The laser output modification unit activates the laser irradiation after the bubble disappears between the laser emission end and the broken object.

3. The waveform control device for the laser fragmentation apparatus according to claim 2, wherein, By reducing the output of the laser to a level that does not cause an increase in the temperature of the liquid, the formation of bubbles can be suppressed.

4. The waveform control device for the laser fragmentation apparatus according to claim 1, wherein, The waveform control device for the laser breaking apparatus includes a frequency adjustment unit that adjusts the repetition frequency of the laser. The repetition frequency is above 1.7 kHz and / or below 3.0 kHz.

5. The waveform control device for the laser fragmentation apparatus according to claim 4, wherein, The repetition frequency is above 1.7 kHz and below 3.0 kHz.

6. The waveform control device for the laser fragmentation apparatus according to claim 4, wherein, The repetition frequency is above 1.7 kHz and below 2.5 kHz.

7. The waveform control device for the laser fragmentation apparatus according to claim 4, wherein, The repetition frequency is above 2.5 kHz and below 3.0 kHz.

8. A laser fragmentation system, comprising: Ureteroscopy; Laser source; A pulse generation unit that pulses the laser emitted from the laser source. The laser output modification unit modifies the output of the laser pulsed by the pulse generation unit. The laser emission end will emit the laser, after its output has been modified by the laser output modification unit, toward the broken object in the liquid; An image processing unit that images the broken object; and The display unit is connected to the graphics unit. The laser output modification unit continuously emits laser light before the bubble generated from the laser emission end reaches the object to be broken. After the bubble generated from the laser emission end reaches the object to be broken, during the period when there is a bubble between the laser emission end and the object to be broken and the bubble does not connect the laser emission end and the object to be broken, the laser output change unit reduces or shuts down the laser output in sync with the contraction of the bubble.

Images