Laser light irradiation system, laser control device, and laser light irradiation method

Abstract

A laser light irradiation system (1) for irradiating a calculus (S) present in the body with laser light to fragment the calculus (S) in a liquid comprises: a laser fiber (3) having a fiber emission end (3a) from which the laser light is emitted; and at least one processor that controls the frequency of the laser light emitted from the fiber emission end (3a). The processor switches the frequency of the laser light between a first pulse group having a high frequency and a power output for fragmenting the calculus (S), and a second pulse group having a frequency lower than that of the first pulse group and a waveform in which the peak power gradually increases in the direction of the axis for irradiation time, and causes the second pulse group to be emitted at least either before or after the timing at which the first pulse group is emitted.

Description

Laser beam irradiation system, laser control device, and laser beam irradiation method

[0001] The present invention relates to a laser light irradiation system, a laser control device, and a laser light irradiation method.

[0002] Conventionally, a technique for fragmenting kidney stones using laser light has been known (see, for example, Patent Document 1). Stones are fragmented to a desired size by laser irradiation through a stage in which large stones are fragmented (dusting), followed by a stage in which smaller stones are dispersed (popcorn dusting). The technique described in Patent Document 1 changes the frequency of the laser light as one variation of fragmenting stones by laser irradiation.

[0003] International Publication No. 2020 / 033121

[0004] However, Patent Document 1 considers increasing the amount of stone fragmentation and suppressing stone scattering, but does not mention anything about suppressing wasted laser beam shots. High-power laser irradiation generates a strong water flow, so if the stone cannot be crushed all at once with high power, the stone will fly around, resulting in wasted laser beam shots. When wasted laser beam shots occur, the input energy increases accordingly, causing an increase in the patient's intrarenal temperature.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a laser light irradiation system, a laser control device, and a laser light irradiation method that can reduce wasted laser light and shorten surgery time.

[0006] In order to achieve the above object, the present invention provides the following means: A first aspect of the present invention is a laser light irradiation system for fragmenting a calculus present in a body in a liquid by irradiating the calculus with laser light, the system comprising: a laser fiber having a fiber emission end for emitting the laser light; and at least one processor for controlling the frequency of the laser light emitted from the fiber emission end, wherein the processor switches the frequency of the laser light between a first group of high-frequency pulses having an output sufficient to fragment the calculus and a second group of pulses having a lower frequency than the first group of pulses and having a waveform in which the peak power gradually increases in the axial direction of irradiation time, and emits the second group of pulses at least either before or after the timing at which the first group of pulses is emitted.

[0007] According to this aspect, the laser light of the first pulse group has a high fragmentation ability but easily scatters stones. On the other hand, the laser light of the second pulse group has a low fragmentation ability but a high suction effect that draws stones toward the fiber output end within a certain range from the fiber output end. In particular, the laser light of the second pulse group has a waveform in which the peak power gradually increases in the axial direction of the irradiation time, and therefore has a higher suction effect than a laser light having a rectangular waveform.

[0008] Therefore, by having the processor emit the laser light of the first pulse group and the laser light of the second pulse group at different times, the fragmentation effect of the laser light of the first pulse group and the suction effect of the laser light of the second pulse group can compensate for their respective disadvantages, thereby improving fragmentation efficiency. This makes it possible to prevent wasted laser light, which occurs when laser light is emitted when a stone is located at a position far from the fiber emission end, and shortens the surgery time.

[0009] In the laser light irradiation system according to the above aspect, the waveform of the first pulse group may be a multi-pulse train. With this configuration, the laser light of the first pulse group can be irradiated intensively on the stone in a short time before the stone scatters.

[0010] In the laser light irradiation system according to the above aspect, the waveform of the second pulse group may be a triangular waveform in which the peak power gradually increases in the axial direction, or an M-shaped waveform in which the peak power gradually decreases and then gradually increases in the axial direction.

[0011] With this configuration, when the second pulse group has a triangular waveform, multiple bubbles are generated consecutively from the fiber tip, and then adjacent bubbles combine to form a snowball-shaped mass of bubbles. This enhances the suction effect. On the other hand, when the second pulse group has an M-shaped waveform, laser light with a high peak power is emitted with a time interval between laser light with a low peak power, generating two bubbles spaced apart from each other from the fiber tip. This enhances the suction effect.

[0012] In the laser light irradiation system according to the above aspect, the processor may be configured to execute a pulse set multiple times, after an emission period consisting of a period for emitting the first pulse group and a period for emitting the second pulse group, with a stop period during which emission of the laser light is stopped for a certain period of time.

[0013] With this configuration, the laser light is not emitted during the pause period, so the average power of the laser light emitted in each pulse set can be reduced, thereby preventing the patient's intrarenal temperature from rising.

[0014] In the laser light irradiation system according to the above aspect, the processor may determine the power of the first pulse group, the power of the second pulse group, and the length of the stop period within a range in which the average power of the laser light emitted in the pulse set is 20 W or less.

[0015] In the laser light irradiation system according to the above aspect, the average power may be calculated by the following equations (1), (2), and (3). P ａｖｅ is the average power, PE Ａ and P.E. Ｈ is the pulse energy, f Ａ and f Ｈis the frequency, N Ａ and N Ｈ is the number of pulses, T ｉｎｔ is the stop period.

[0016] In the laser light irradiation system according to the above aspect, the processor may implement the second pulse set, following the first pulse set, with the stop period provided after an emission period consisting of a period for emitting a third pulse group having an output for breaking up the stone and having a high frequency different from that of the first pulse group, and a period for emitting a fourth pulse group having a frequency different from that of the second pulse group but lower than that of the third pulse group and having a waveform in which peak power gradually increases in the axial direction of irradiation time.

[0017] The laser light irradiation system according to the above aspect may include an endoscope that can be inserted into the body, and the endoscope may have a channel through which the laser fiber can pass and through which the fiber exit end can protrude forward.

[0018] A second aspect of the present invention is a laser control device that includes at least one processor that controls the frequency of laser light emitted from the fiber emission end of a laser fiber toward a stone present in the body, and the processor switches the frequency of the laser light between a first group of high-frequency pulses having an output that can fragment the stone and a second group of pulses that has a lower frequency than the first group of pulses and has a waveform in which the peak power gradually increases in the axial direction of the irradiation time, and emits the second group of pulses at least either before or after the timing at which the first group of pulses is emitted.

[0019] In the laser control device according to the above aspect, the waveform of the first pulse group may be a multi-pulse train. In the laser control device according to the above aspect, the waveform of the second pulse group may be a triangular waveform in which peak power gradually increases in the axial direction, or an M-shaped waveform in which peak power gradually decreases and then gradually increases in the axial direction.

[0020] In the laser control device according to the above aspect, the processor may be configured to execute a pulse set multiple times, after an emission period consisting of a period for emitting the first pulse group and a period for emitting the second pulse group, with a stop period in which emission of the laser light is stopped for a certain period of time.

[0021] In the laser control device according to the above aspect, the processor may determine the power of the first pulse group, the power of the second pulse group, and the length of the stop period within a range in which the average power of the laser light emitted in the pulse set is 20 W or less.

[0022] In the laser control device according to the above aspect, the average power may be calculated by the following equations (1), (2), and (3). P ａｖｅ is the average power, PE Ａ and P.E. Ｈ is the pulse energy, f Ａ and f Ｈ is the frequency, N Ａ and N Ｈ is the number of pulses, T ｉｎｔ is the stop period.

[0023] In the laser control device according to the above aspect, the processor may implement the second pulse set, following the first pulse set, with the stop period provided after an emission period consisting of an emission period of a third pulse group having an output for breaking up the stone and having a high frequency different from that of the first pulse group, and an emission period of a fourth pulse group having a frequency different from that of the second pulse group but lower than that of the third pulse group and having a waveform in which peak power gradually increases in the axial direction of irradiation time.

[0024] A third aspect of the present invention is a laser light irradiation method for fragmenting a concretion present in a body in a liquid by irradiating the concretion with laser light, the method comprising: emitting a first group of high-frequency pulses having an output sufficient to fragment the concretion from a fiber emission end toward the concretion; and emitting a second group of pulses having a lower frequency than the first group of pulses and having a waveform in which the peak power gradually increases in the axial direction of irradiation time, at least either before or after the timing of emitting the first group of pulses.

[0025] The laser light irradiation method according to the above aspect may be configured to execute a pulse set multiple times, the pulse set including an emission period consisting of an emission period of the first pulse group and an emission period of the second pulse group, followed by a stop period in which emission of the laser light is stopped for a certain period of time.

[0026] The laser light irradiation method according to the above aspect may determine the power of the first pulse group, the power of the second pulse group, and the length of the stop period so that the average power of the laser light emitted in the pulse set is 20 W or less.

[0027] In the laser light irradiation method according to the above aspect, the average power may be calculated by the following formulas (1), (2), and (3). P ａｖｅ is the average power, PE Ａ and P.E. Ｈ is the pulse energy, f Ａ and f Ｈ is the frequency, N Ａ and N Ｈ is the number of pulses, T ｉｎｔ is the stop period.

[0028] The laser light irradiation method according to the above aspect may also be configured to execute, following the first pulse set, a second pulse set having the stop period after an emission period consisting of a period for emitting a third pulse group having an output for breaking up the stone and having a high frequency different from that of the first pulse group, and a period for emitting a fourth pulse group having a frequency different from that of the second pulse group but lower than that of the third pulse group and having a waveform in which peak power gradually increases in the axial direction of irradiation time.

[0029] According to the present invention, it is possible to reduce the amount of wasted laser light and shorten the operation time.

[0030] 1 is a schematic configuration diagram of a laser light irradiation system according to an embodiment of the present invention. FIG. 1 is a diagram illustrating a state in which a laser fiber is inserted into a working channel of an endoscope. FIG. 2 is a diagram illustrating that control conditions for the frequency of laser light are determined by a determination unit from information acquired by a sensor. FIG. 3 is a table illustrating an example of the frequency of laser light in Dusting mode and Popcorning mode. FIG. 4 is a diagram illustrating selection of a mode stored in a storage unit using a touch panel. FIG. 5 is a diagram illustrating manual input of control conditions by a user using a touch panel. FIG. 6 is a block diagram illustrating the configuration of a laser control device. FIG. 7 is a diagram illustrating an example of a switching pattern between a first pulse group and a second pulse group. FIG. 8 is a diagram illustrating the pulse width of the first pulse group. FIG. 9 is a diagram illustrating the duty ratio of the first pulse group. FIG. 10 is a diagram illustrating a second pulse group having a triangular waveform. FIG. 11 is a flowchart illustrating a laser light irradiation method according to an embodiment of the present invention. FIG. 12 is a diagram illustrating a pattern in which a first pulse group is emitted first, and then the frequency of laser light is switched. FIG. 13 is a diagram illustrating a pattern in which a second pulse group is emitted both before and after emission of the first pulse group. FIG. 14 is a diagram illustrating a first pulse group having a waveform that gradually increases in a stepwise manner in the irradiation time axis direction. 1 is a diagram illustrating a second pulse group having an M-shaped waveform; FIG. 2 is a diagram illustrating a second pulse group having a U-shaped waveform; FIG. 3 is a diagram illustrating a second pulse group having a rectangular waveform; FIG. 4 is a diagram illustrating an example of a pattern in which the number of pulses in the first pulse group is different for each pulse set, or the waveform of the second pulse group is different; FIG. 5 is a diagram illustrating the scattering movement of a stone irradiated with laser light in a renal calyx where the approach direction is oriented horizontally; FIG. 6 is a diagram illustrating the scattering movement of a stone irradiated with laser light in a renal calyx where the approach direction is oriented in the direction of gravity.

[0031] A laser light irradiation system, a laser control device, and a laser light irradiation method according to one embodiment of the present invention will be described below with reference to the drawings. As shown in Fig. 1, the laser light irradiation system 1 according to this embodiment irradiates a calculus S present in the body with laser light to break up the calculus S in liquid. In the drawing, the symbol C indicates the renal calyx where the calculus S is retained.

[0032] The laser light irradiation system 1 includes a laser fiber 3 having a fiber emission end 3a that emits laser light, a laser control device 5 that controls the frequency of the laser light emitted from the fiber emission end 3a, a sensor 7 that detects the state of the stone S, a judgment unit (processor) 9 that determines the control conditions for the frequency of the laser light, a memory unit 11 that stores preset data, and a manual input unit 13 such as a mouse, keyboard, or touch panel. The frequency here refers to the pulse repetition frequency.

[0033] 2, the laser light irradiation system 1 is also provided with an endoscope (endoscope) 21 that can be inserted into the body. The endoscope 21 is provided with a working channel (channel) 21a through which the laser fiber 3 passes and through which the fiber exit end 3a can protrude forward.

[0034] The laser fiber 3 may be, for example, either a single-mode fiber or a multi-mode fiber, or may be a fiber with a double clad structure.

[0035] The sensor 7 is, for example, a camera. The sensor 7 acquires, for example, endoscopic images, X-ray images, or ultrasound images of the stones S in the liquid. Based on the acquired images of the stones S, the sensor 7 also acquires information about the state of the stones S, such as their size, number, type, or shape, as well as information about the size, shape, or direction of gravity of the closed space into which the laser light is irradiated. The type of stones S can be determined by examining their composition using laser-induced breakdown spectroscopy or the like. The size, number, and shape of the stones S can be determined using, for example, endoscopy images, X-ray fluoroscopy, or ultrasound images.

[0036] As shown in Fig. 3, the determination unit 9 determines optimal control conditions for controlling the frequency of the laser light based on information acquired by the sensor 7, i.e., information on the state of the stone S and information on the state of the space. Since the way in which the stone S breaks varies depending on the size, number, type, or shape of the stone S, or the size, shape, or direction of gravity of the closed space into which the laser light is irradiated, this configuration makes it possible to more efficiently fragment the stone S. The processing by the determination unit 9 is executed by at least one processor including hardware. The determination of each parameter when the determination unit 9 determines the optimal control conditions will be described later.

[0037] Preset data of a plurality of control conditions for controlling the frequency of the laser light is stored in the storage unit 11. The preset data may be a compilation of optimal frequencies of the laser light obtained by conducting experiments in advance while changing the frequency of the laser light depending on, for example, the size, number, type, or shape of the stones S, or the size, shape, or direction of gravity of the closed space to which the laser light is irradiated.

[0038] For example, as shown in Fig. 4, the optimum laser light frequency and the like may be grouped according to the stage of crushing, such as a dusting mode for crushing large stones and a popcorning mode for further crushing smaller stones. In this case, the user can set the optimum control conditions according to the stage of crushing simply by switching the mode using the touch panel 13 or a foot switch (not shown), for example, as shown in Fig. 5.

[0039] The manual input unit 13 allows the user to input desired control conditions related to the control of the frequency of the laser light. For example, as shown in Fig. 6 , the user may manually input the desired control conditions using the touch panel 13.

[0040] The laser control device 5 is realized by, for example, a dedicated or general-purpose computer. That is, as shown in Fig. 7, the laser control device 5 includes at least one processor 15 such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), a main storage device 17, and an auxiliary storage device 19.

[0041] The main storage device 17 is a RAM (Random Access Memory) or the like used as a work area for the processor 15. The auxiliary storage device 19 is a computer-readable non-transitory recording medium such as an SSD (Solid State Drive) or an HDD (Hard Disk Drive). The auxiliary storage device 19 stores a control program that causes the processor 15 to execute processing. The main storage device 17 and the auxiliary storage device 19 may be connected to the laser control device 5 via a network.

[0042] The laser control device 5 is also equipped with a light source unit (not shown) that emits laser light to fragment the calculus S. The laser light emitted from the light source unit is guided through the laser fiber 3 and then emitted from the fiber emission end 3 a.

[0043] In accordance with the user's settings, the laser control device 5 receives control conditions input via the manual input unit 13, control conditions stored in the storage unit 11, or control conditions determined by the determination unit 9. Then, the laser control device 5 switches the frequency of the laser light oscillated from the light source unit based on the input control conditions.

[0044] Specifically, as shown in FIG. 8, the laser control device 5 switches the frequency of the laser light between a first group of high-frequency pulses having an output sufficient to break up the stone S, and a second group of pulses having a lower frequency than the first group of pulses and a waveform in which the peak power gradually increases in the axial direction of the irradiation time.

[0045] The waveform of the first pulse group is a multi-pulse train (MPT) in which laser light is divided into several pulses and emitted, as shown in Fig. 8 to Fig. 10. Setting parameters for the first pulse group include the width of each pulse (pulse width) as shown in Fig. 9, or the duty ratio of the pulse width between each pulse as shown in Fig. 10. The pulse width of the first pulse group is within a range of, for example, 100 to 400 μs.

[0046] The waveform of the second pulse group is a triangular waveform in which the peak power increases linearly in the direction of the irradiation time axis, as shown in Fig. 11. The pulse width of the second pulse group is within a range of, for example, 400 to 1600 µs.

[0047] As shown in Fig. 8, the laser control device 5 repeatedly emits a first pulse group at a predetermined cycle (For ablation), and then switches the frequency to repeatedly emit a second pulse group at a predetermined cycle (For hold). After emitting the second pulse group, an interval (stop period) is provided during which the emission of the laser light is stopped for a certain period. The laser control device 5 executes a pulse set consisting of the emission period of the first pulse group, the emission period of the second pulse group, and the interval multiple times. Each of the above processes by the laser control device 5 is executed by the processor 15.

[0048] Next, we will explain how the determining unit 9 determines each parameter when determining the optimal control conditions. The determining unit 9 determines each parameter that satisfies the following conditions: the total pulse energy PE in each pulse set is 0.5 to 10 J, and the frequency f of each pulse set is 0.5 to 10 H. Ｚ , the average power P of the laser light emitted in each pulse set ａｖｅ is 1 to 50 W per second, and the frequency of the first pulse group is f Ａ > Frequency f of the second pulse group Ｈ , the pulse energy PE of the first pulse group in each pulse set Ａ >Pulse energy PE of the second pulse group in each pulse set Ｈ .

[0049] The average power P of the laser light emitted in each pulse set ａｖｅ is calculated by the determination unit 9 using the following equations (1), (2), and (3). Here, P ａｖｅ is the average power, PE Ａ is the pulse energy of the first pulse group, PE Ｈ is the pulse energy of the second pulse group, f Ａ is the frequency of the first pulse group, f Ｈ is the frequency of the second pulse group, N Ａ is the number of pulses in the first pulse group, N Ｈ is the number of pulses in the second pulse group, T ｉｎｔ represents the interval.

[0050] The average power of the laser light is determined depending on the state of the stones S or the state of the closed space into which the laser light is irradiated. If the size or shape of the stones S changes, the resistance between the stones S, the resistance at the walls of the closed space into which the laser light is irradiated, or the resistance to the water flow changes, and therefore the appropriate average power of the laser light also changes. If the number of stones S changes, the weight of the stones S as a whole also changes, and therefore the appropriate average power of the laser light also changes. If the size of the closed space into which the laser light is irradiated changes, the height at which the stones S fly also changes, and therefore the appropriate average power of the laser light also changes. If the direction of gravity in the closed space into which the laser light is irradiated changes, the way the stones S remain around the fiber emission end 3a after irradiation with the laser light also changes, and therefore the appropriate average power of the laser light also changes.

[0051] In this embodiment, the determining unit 9 determines the average power P of the laser light emitted in each pulse set. ａｖｅ It is preferable to determine the power of the first pulse group, the power of the second pulse group, and the length of the interval so that the average power P of the laser beam in the pulse set is 20 W or less. The longer the interval, the lower the average power of the laser beam in the pulse set. Therefore, by adjusting the length of the interval, the average power P of the laser beam can be reduced. ａｖｅ is kept at 20 W or less. The length of the interval is determined, for example, after the power of the first pulse group is determined and then the power of the second pulse group is determined.

[0052] Next, the relationship between the frequency of the laser light and the fragmenting force and suction effect will be described. The first pulse group, which is high frequency, has a shorter laser light irradiation interval than the second pulse group, which is low frequency. In the first pulse group, when the laser light is emitted from the fiber output end 3a in liquid, bubbles are generated from the fiber output end 3a, and the laser light passes through the bubbles and is irradiated onto the stone S. This causes the stone to fragment, but the impact of the fragmentation causes the stone S to move in a direction away from the fiber output end 3a.

[0053] Subsequently, when the bubble begins to contract due to cooling by the surrounding liquid, a suction force is generated. As a result, within a certain range from the fiber output end 3a, a suction effect occurs in which the stone S present within that range is drawn toward the fiber output end 3a. However, before the stone S drawn to the fiber output end 3a is positioned within the irradiation range of the laser light, the next laser beam is emitted. As a result, the drawn stone S is not irradiated with the laser beam, or the stone S rotates when the edge of the stone S is irradiated with the laser beam, and the stone S moves again in a direction away from the fiber output end 3a due to the impact of fragmentation.

[0054] Therefore, the first pulse group has a high ability to break up the calculus S by being ejected at high density in a short time, but it also tends to scatter the calculus S.

[0055] On the other hand, in the second pulse group having a low frequency and a triangular waveform, when the laser light is emitted from the fiber emitting end 3a in the liquid, bubbles are generated from the fiber emitting end 3a, and the laser light passes through the bubbles and is irradiated onto the stone S. Then, the stone S moves in a direction away from the fiber emitting end 3a due to the impact of fragmentation.

[0056] Subsequently, when the bubble begins to contract due to cooling by the surrounding liquid, a suction effect is exerted within a certain range from the fiber emitting end 3a, thereby drawing the calculus S present within the certain range toward the fiber emitting end 3a.

[0057] Next, the next laser beam is emitted with the stone S attracted to the fiber output tip 3a positioned within the irradiation range of the laser beam. This again generates bubbles, and the stone S is irradiated with the laser beam that has passed through the bubbles. The impact of the fragmentation again moves the stone S away from the fiber output tip 3a. In this case, too, when the bubbles begin to contract due to cooling by the surrounding liquid, a suction force is generated, and a suction effect acts within a certain range from the fiber output tip 3a. As a result, the stone S present within the certain range is attracted to the fiber output tip 3a.

[0058] In other words, the second pulse group can draw the stone S by its suction effect and cause it to slip directly below the fiber output end 3a. Therefore, although the second pulse group has a low fragmentation ability, it has a high suction effect of drawing the stone S to the fiber output end 3a within a certain range from the fiber output end 3a. In particular, in the case of the second pulse group with a triangular waveform, two or three bubbles are generated adjacently in time from the fiber output end 3a, and then these bubbles join together to form a snowball-shaped mass of bubbles. This results in a higher suction effect than laser light with a square waveform.

[0059] Next, the operation of the laser light irradiation system 1, laser control device 5, and laser light irradiation method configured as described above will be described with reference to the flowchart in Fig. 12. To fragment a calculus S present in the body using the laser light irradiation system 1, laser control device 5, and laser light irradiation method according to this embodiment, first, an endoscope is placed inside the body (step S1). Then, as shown in Fig. 2, the laser fiber 3 is inserted into the working channel 21a of the endoscope 21, and the fiber emission end 3a is placed facing the calculus S to be treated.

[0060] Next, the user sets the control conditions (laser conditions) for the frequency of the laser light by inputting desired control conditions through the manual input unit 13 or by selecting control conditions stored in the storage unit 11 (step S2). Information on the state of the stone S or the space may be acquired by the sensor 7 while the stone S is being crushed, and the control conditions for the frequency of the laser light may be determined by the determination unit 9 based on the acquired information. Then, the control conditions determined by the determination unit 9 may be set.

[0061] Next, the laser control device 5 causes the light source unit to emit laser light based on the set control conditions (step S3). The emitted laser light then passes through the laser fiber 3 and is irradiated onto the stone S from the fiber emission end 3a (step S4).

[0062] In steps S3 and S4, as shown in Fig. 8, the laser control device 5 repeatedly emits a first group of high-frequency pulses of laser light at a predetermined cycle, and then switches the frequency to repeatedly emit a second group of low-frequency pulses of triangular waveform laser light at a predetermined cycle. After that, the emission of the laser light is stopped for a certain period. Then, a pulse set consisting of this emission period and interval is repeated a predetermined number of times.

[0063] In this case, when the first group of high-frequency pulses is repeatedly emitted, bubbles generated from the fiber emission tip 3a are in contact with both the fiber emission tip 3a and the stone S, and the emitted laser light passes through the bubbles and is irradiated onto the stone S. As a result, the stone S irradiated with the laser light is fragmented. The first group of pulses has a high fragmenting ability for fragmenting the stone S, but the impact of fragmentation causes the stone S to scatter. The scattered stone S moves in a direction away from the fiber emission tip 3a.

[0064] Next, by switching from the first pulse group to the second pulse group, the second pulse group, which has a low frequency and a triangular waveform, is repeatedly emitted. In this case, too, the laser light that has passed through the bubbles generated from the fiber output end 3a is irradiated onto the stone S. Although the second pulse group has a low ability to fragment the stone S, it has a high suction effect that acts when the bubbles begin to disappear. Therefore, the stone S present within a certain range from the fiber output end 3a can be drawn to the fiber output end 3a by the high suction effect, and then can be made to slip directly below the fiber output end 3a.

[0065] Therefore, in each pulse set, the stone S that moves away from the fiber output end 3a due to the irradiation of the first pulse group can be held at the fiber output end 3a by the irradiation of the second pulse group. Then, with the stone S attracted to the fiber output end 3a by the irradiation of the second pulse group positioned within the irradiation range of the laser light, the high-frequency first pulse group of the next pulse set is emitted after an interval has elapsed. This allows the stone S to be effectively irradiated with the laser light of the first pulse group, and the stone S to be highly efficiently fragmented.

[0066] Each pulse set is repeated until the stone S is fragmented to a desired size, for example, less than 1 mm. Note that, when the stone S is fragmented to the desired size, it is not necessary to repeat the pulse set, and it is sufficient to switch between the first pulse group and the second pulse group only once.

[0067] As described above, according to the laser light irradiation system 1, laser control device 5, and laser light irradiation method of this embodiment, the laser light of the first pulse group and the laser light of the second pulse group are emitted at different times, so that the fragmentation effect of the laser light of the first pulse group and the suction effect of the laser light of the second pulse group can compensate for their respective disadvantages, thereby improving fragmentation efficiency. This makes it possible to prevent wasted laser light, which occurs when laser light is emitted when the stone S is located at a position away from the fiber emission end 3a, and shortens the surgery time.

[0068] Furthermore, by providing an interval after the emission period in each pulse set, the average power of the laser light emitted in each pulse set can be reduced, and by keeping the average power of the laser light in each pulse set at 20 W or less, it is possible to sufficiently prevent the patient's intrarenal temperature from increasing.

[0069] In this embodiment, in each pulse set, the second pulse group is emitted after the first pulse group is emitted, but it is acceptable to emit the second pulse group at least either before or after the timing at which the first pulse group is emitted.

[0070] For example, as shown in Fig. 13, in each pulse set, the second pulse group may be emitted first, and then the frequency of the laser light may be switched to emit the first pulse group. With this configuration, in each pulse set, the stone S present within a certain range from the fiber output end 3a can be drawn to the fiber output end 3a by the irradiation of the second pulse group, and then the first pulse group can be irradiated. In this case, an interval may be provided after the emission of the first pulse group.

[0071] 14, for example, the second pulse group may be emitted both before and after the emission of the first pulse group in each pulse set. With this configuration, in each pulse set, the stone S present within a certain range from the fiber emitting end 3a can be drawn to the fiber emitting end 3a by the irradiation of the second pulse group, and then the first pulse group can be emitted. Furthermore, the stone S that moves away from the fiber emitting end 3a due to the irradiation of the first pulse group can be kept at the fiber emitting end 3a by the irradiation of the second pulse group. In this case, an interval may be provided after the second pulse group, the first pulse group, and the second pulse group are emitted in this order.

[0072] In addition, in this embodiment, the waveform of the second pulse group has been described as a triangular waveform that gradually increases linearly, but the waveform is not limited to a triangular waveform as long as the peak power gradually increases in the direction of the irradiation time axis. For example, the waveform may be one that gradually increases in a stepwise manner in the direction of the irradiation time axis as shown in Figure 15, or one that gradually increases in a smooth curve.

[0073] The waveform of the second pulse group may be an M-shaped waveform in which the peak power gradually decreases and then gradually increases in the direction of the irradiation time axis, as shown in Fig. 16, or a U-shaped waveform in which the peak power suddenly decreases from a high state in the direction of the irradiation time axis, remains in this decreased state for a certain period of time, and then suddenly increases again, as shown in Fig. 17. In either of these waveforms, the pulse width of the second pulse group is preferably in the range of 400 to 1600 μS.

[0074] For the M-shaped waveform and U-shaped waveform, the peak power at the center of the axial direction during irradiation time is preferably within 50% of the peak power at both ends in the axial direction. By arranging the maximum peaks at both ends in the axial direction, separated by a peak power within 50% of the center in the axial direction, two bubbles are generated at a distance from each other from the fiber exit end 3a. This results in a high suction effect.

[0075] The second pulse group may have a square wave shape as shown in Fig. 18. Although the suction effect itself can be obtained when a square wave is used, the square wave does not generate the clustered bubbles that are formed in the case of a triangular waveform or the two separate bubbles that are generated in the case of an M-shaped waveform or a U-shaped waveform.

[0076] In this embodiment, for example, as shown in FIG. 19, the number of pulses in the first pulse group may be different for each pulse set, and the waveform of the second pulse group may be different for each pulse set.

[0077] In the example shown in FIG. 19 , a first pulse set consisting of a first pulse group A1 of high frequency in a multi-pulse train in which the pulse is divided into a reduced number of parts, a second pulse group H1 which has a lower frequency than the first pulse group A1 and has a triangular waveform, and an interval, and a second pulse set consisting of a first pulse group (third pulse group) A2 of high frequency in a multi-pulse train in which the pulse is divided into a greater number of parts than the first pulse group A1, a second pulse group (fourth pulse group) H2 which has a lower frequency than the first pulse group A2 and has a U-shaped waveform, and an interval, are repeated alternately.

[0078] The first pulse group A2 may have any frequency different from that of the first pulse group A1, and may have a smaller number of divided pulses than the first pulse group A1, for example. The second pulse group H2 may have any frequency different from that of the second pulse group H1 and lower than that of the first pulse group A2, and may have a waveform in which the peak power gradually increases along the axis of irradiation time.

[0079] Here, the approach direction of the laser fiber 3 toward the stone S in the renal calyx C differs for each renal calyx C in which the stone S is retained. In a renal calyx C in which the approach direction is horizontal, as shown in Fig. 20 for example, if the stone S is scattered from the fiber tip 3a toward the base end of the laser fiber 3 by the impact of the laser light, the stone S will not return to the irradiation position of the laser light due to gravity. Therefore, in this case, control conditions that emphasize the suction effect are desirable.

[0080] On the other hand, in the case of the renal calyx C where the approach direction is in the direction of gravity, for example, as shown in Figure 21, when the stone S is scattered from the fiber tip 3a toward the base end of the laser fiber 3 by the impact of the laser light, the stone S returns to the irradiation position of the laser light due to gravity. Therefore, in this case, control conditions that emphasize fragmentation are desirable.

[0081] Furthermore, if a stone S is located within the irradiation range of the laser light when the second pulse group is irradiated, the stone S may be fragmented by the laser light of the second pulse group. The second pulse groups of triangular and M-shaped waveforms have a suction effect during periods when the peak power is low, but they have difficulty scattering the stone S due to their reduced average power. Therefore, the second pulse groups of triangular and M-shaped waveforms are suitable for renal calyces C in which the approach direction is horizontal, where scattering of the stone S is desired as little as possible, and can further increase the fragmentation efficiency in such renal calyces C.

[0082] On the other hand, the second pulse group of U-shaped and square waveforms has a long maximum peak power duration and therefore a high average power per pulse, and therefore has a high suction effect and high crushing ability, but is likely to scatter the stone S during crushing. Therefore, the second pulse group of U-shaped and square waveforms is suitable for a renal calyx C where the approach direction to which the stone S returns even after being scattered is in the direction of gravity, and can further improve the crushing efficiency in such a renal calyx C.

[0083] 19, a first pulse set having a first group A1 of high-frequency pulses with a reduced number of divided pulses and a second group H1 of low-frequency triangular waveform pulses is particularly effective for the renal calyces C whose approach direction is horizontal. On the other hand, a second pulse set having a first group A2 of high-frequency pulses with a greater number of divided pulses and a second group H2 of low-frequency U-shaped waveform pulses is particularly effective for the renal calyces C whose approach direction is in the direction of gravity.

[0084] 19, by appropriately combining a first pulse set having a second pulse group with a triangular or M-shaped waveform and a second pulse set having a second pulse group with a U-shaped or rectangular waveform, the method can be applied to renal calyces C whose approach direction is either horizontal or in the direction of gravity, thereby comprehensively fragmenting stones S. It is also effective for renal calyces C whose approach direction is tilted at an angle between the horizontal and the direction of gravity, and is also effective when moving between several renal calyces C whose orientations are different.

[0085] In addition, in the present embodiment, the frequency of the laser light is switched between the first pulse group and the second pulse group. Alternatively, the laser control device 5 may switch the frequency of the laser light between three or more different frequencies.

[0086] In addition, in this embodiment, the judgment unit 9 is provided separately from the processor 15 of the laser control device 5, but instead, the processor 15 of the laser control device 5 may also perform the function of the judgment unit 9.

[0087] Furthermore, as the peak power increases, the bubbles generated from the fiber exit end 3a also increase. Furthermore, as the pulse width of the laser light increases, the number of bubbles that repeatedly appear and disappear with one pulse increases. Because these phenomena affect the stone S fragmentation effect and the suction effect, the judgment unit 9 may execute a process to optimize the laser conditions, thereby changing not only the frequency but also the peak power, pulse width, perfusion rate, etc. Different types of stones S have different hardness and density due to differences in composition, which results in different fragmentation methods. Therefore, sensing the type of stone S is useful for optimizing the frequency, peak power, and pulse width.

[0088] In addition, in this embodiment, the control conditions set by the determination unit 9 can be adopted for controlling the frequency of the laser light. Alternatively, the laser light irradiation system 1 may not include the sensor 7 and the determination unit 9, and may adopt control conditions input by the user via the manual input unit 13 and control conditions stored in the storage unit 11. In this case, steps S2 to S4 may be executed based on each control condition. When the control conditions stored in the storage unit 11 are adopted, the parameters of the first pulse group and the second pulse group can be set more quickly and easily.

[0089] In this embodiment, the judgment unit 9 may also determine whether the stone S has been broken down to a size smaller than a predetermined threshold based on information about the state of the stone S. If it is determined that the stone S has not been broken down to a size smaller than the predetermined threshold, steps S2 to S4 may be repeated. If it is determined that the stone S has been broken down to a size smaller than the predetermined threshold, the judgment unit 9 may issue an instruction to the laser control device 5 to terminate laser irradiation.

[0090] Although this embodiment has been described using urinary stones as an example, the effects of the multi-pulse train are not limited to the treatment of urinary stones, but can also be obtained for bile duct stones. Furthermore, this embodiment is not limited to urinary stones, but can be applied to the treatment of any biological tissue in water, an aqueous solution, an organic solution, or the atmosphere.

[0091] Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design modifications and the like are also included within the scope of the present invention. For example, the present invention is not limited to the above-described embodiments and modifications, but may be applied to embodiments in which these embodiments and modifications are appropriately combined, and is not particularly limited.

[0092] REFERENCE SIGNS LIST 1 Laser light irradiation system 3 Laser fiber 3a Fiber emission end 5 Laser control device 9 Determination unit (processor) 15 Processor 21 Endoscope (endoscope) 21a Working channel (channel) S Stone

Claims

1. A laser light irradiation system for crushing a calculus existing in a body by irradiating the calculus with laser light in a liquid, comprising: a laser fiber having a fiber emission end for emitting the laser light; and at least one processor for controlling the frequency of the laser light emitted from the fiber emission end, wherein the processor switches the frequency of the laser light to a first high-frequency pulse group having an output for crushing the calculus and a second pulse group having a waveform in which the frequency is lower than that of the first pulse group and the peak power gradually increases in the axial direction of the irradiation time, and the second pulse group is emitted at least on one side before or after the timing of emitting the first pulse group.

2. The laser light irradiation system according to claim 1, wherein the waveform of the first pulse group is a multi-pulse train.

3. The laser light irradiation system according to claim 1 or claim 2, wherein the waveform of the second pulse group is a triangular waveform in which the peak power gradually increases in the axial direction or an M-shaped waveform in which the peak power gradually decreases in the axial direction and then gradually increases.

4. The laser light irradiation system according to claim 1, wherein the processor repeatedly performs a plurality of pulse sets each provided with a stop period for stopping the emission of the laser light for a certain period after an emission period composed of the emission period of the first pulse group and the emission period of the second pulse group.

5. The laser light irradiation system according to claim 4, wherein the processor determines the power of the first pulse group, the power of the second pulse group, and the length of the stop period within a range where the average power of the laser light emitted in the pulse set is 20 W or less.

6. The laser light irradiation system according to claim 5, wherein the average power is calculated by the following formulas (1), (2), and (3). P ａｖｅ is the average power, PE Ａ and PE Ｈ are the pulse energies, f Ａ and f Ｈ is the frequency, N Ａ and N Ｈ are the number of pulses, T ｉｎｔ is the stop period.

7. The laser light irradiation system according to any one of claims 4 to 6, wherein the processor performs a second pulse set provided with the stop period after an emission period composed of an emission period of a third pulse group having an output for crushing the calculus and having a high frequency different from that of the first pulse group and an emission period of a fourth pulse group having a frequency different from that of the second pulse group, being lower than the third pulse group, and having a waveform in which the peak power gradually increases in the axial direction of the irradiation time, following the first pulse set.

8. The laser light irradiation system according to claim 1, further comprising an endoscope insertable into the body, wherein the endoscope is provided with a channel through which the laser fiber passes and the fiber emission end can protrude forward.

9. A laser control device comprising at least one processor configured to control the frequency of laser light emitted from the fiber output end of a laser fiber toward a calculus present in a body, the processor switching the frequency of the laser light to a first high-frequency pulse group having an output for crushing the calculus and a second pulse group having a waveform with a frequency lower than that of the first pulse group and a peak power that gradually increases in the axial direction of the irradiation time, and emitting the second pulse group at least on one side before or after the timing of emitting the first pulse group.

10. The laser control device according to claim 9, wherein the waveform of the first pulse group is a multi-pulse train.

11. The laser control device according to claim 9 or claim 10, wherein the waveform of the second pulse group is a triangular waveform in which the peak power gradually increases in the axial direction or an M-shaped waveform in which the peak power gradually decreases in the axial direction and then gradually increases.

12. The laser control device according to claim 9, wherein the processor repeatedly performs a plurality of pulse sets each provided with a stop period for stopping the emission of the laser light for a certain period after an emission period consisting of the emission period of the first pulse group and the emission period of the second pulse group.

13. The laser control device according to claim 12, wherein the processor determines the power of the first pulse group, the power of the second pulse group, and the length of the stop period within a range where the average power of the laser light emitted in the pulse set is 20 W or less.

14. The laser control device according to claim 13, wherein the average power is calculated by the following formulas (1), (2), and (3). P ａｖｅ is the average power, PE Ａ and PE Ｈ is the pulse energy, f Ａ and f Ｈ is the frequency, N Ａ and N Ｈ is the number of pulses, T ｉｎｔ is the stop period.

15. The laser control device according to any one of claims 12 to 14, wherein the processor, following the first pulse set, performs a second pulse set provided with the stop period after an emission period consisting of the emission period of a third pulse group having an output for crushing the calculus and a frequency different from that of the first pulse group and the emission period of a fourth pulse group having a frequency different from that of the second pulse group, lower than that of the third pulse group, and a waveform in which the peak power gradually increases in the axial direction of the irradiation time.

16. A laser light irradiation method for crushing a calculus existing in a body by irradiating the calculus with laser light in a liquid, comprising: emitting a first high-frequency pulse group having an output for crushing the calculus from a fiber emission end toward the calculus; and emitting a second pulse group having a frequency lower than that of the first pulse group and having a waveform in which the peak power gradually increases in the axial direction of the irradiation time at at least one of the front and rear of the timing of emitting the first pulse group.

17. The laser light irradiation method according to claim 16, wherein a plurality of pulse sets are performed, each pulse set including a stop period in which the emission of the laser light is stopped for a certain period after an emission period including the emission period of the first pulse group and the emission period of the second pulse group.

18. The laser light irradiation method according to claim 17, wherein the power of the first pulse group, the power of the second pulse group, and the length of the stop period are determined within a range where the average power of the laser light emitted in the pulse set is 20 W or less.

19. The laser light irradiation method according to claim 18, wherein the average power is calculated by the following formulas (1), (2), and (3). P ａｖｅ is the average power, PE Ａ and PE Ｈ are the pulse energy, f Ａ and f Ｈ are the frequency, N Ａ and N Ｈ are the number of pulses, T ｉｎｔ is the pause period.

20. The laser light irradiation method according to any one of claims 17 to 19, wherein, following the first pulse set, a second pulse set is performed, the second pulse set including a stop period after an emission period including an emission period of a third pulse group having an output for crushing the calculus and having a high frequency different from that of the first pulse group, and an emission period of a fourth pulse group having a frequency different from that of the second pulse group, lower than that of the third pulse group, and having a waveform in which the peak power gradually increases in the axial direction of the irradiation time.

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