Spectroscopic detection of optical fiber flashing events

Abstract

To provide systems and methods for determining and controlling a distance between an endoscope tip and a target.SOLUTION: A laser tissue ablation system can include an optical fiber, with a distal end being extendible from an endoscope body of an endoscope. The optical fiber can deliver therapeutic laser light from the distal end of the optical fiber toward a target site, and receive return light at the distal end of the optical fiber. The laser tissue ablation system can include a sensor that can spectrally measure the return light. The laser tissue ablation system can include processor circuitry that can make a first determination, from the spectral measurement of the return light, of whether flashing event light is present in the return light. The flashing event light can be generated when a flashing event occurs at the distal end of the optical fiber. The processor circuitry can generate, in response to the first determination, a flashing event data signal that indicates whether the flashing event has occurred.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 63 / 377,646, filed September 29, 2022, which is incorporated herein by reference in its entirety.

[0002] This document relates generally to endoscopy systems, and more particularly to systems and methods for determining and controlling the distance between an endoscope tip and a target. [Background technology]

[0003] An operator, such as a physician, practitioner, or user, can use an endoscope to provide visual access to a location inside a patient. The operator can insert the endoscope into the patient's body. The endoscope can deliver light to a target being inspected, such as a target anatomical structure or object. The endoscope can collect light reflected from the object. The reflected light can convey information about the target being inspected.

[0004] The endoscope may include a working channel. In some examples, an operator may perform suction through the working channel. In some examples, an operator may pass instruments such as brushes, biopsy needles, or forceps through the working channel. In some examples, an operator may perform minimally invasive surgery through the working channel, such as to remove unwanted tissue or foreign matter from a patient's body.

[0005] An endoscope can use a laser or plasma system to perform laser treatments such as ablation, coagulation, vaporization, fragmentation, and lithotripsy. In laser treatments, an operator can use an endoscope to deliver surgical laser energy to various target treatment areas, such as soft or hard tissue. In lithotripsy, an operator can use an endoscope to deliver surgical laser energy to break up stone structures within a patient's kidney, gallbladder, ureter, or other stone-forming areas, or to ablate large stones into smaller fragments. Summary of the Invention [Means for solving the problem]

[0006] In one example, a laser tissue ablation system may include an optical fiber having a distal end extendable from an endoscope body of an endoscope, the optical fiber configured to deliver therapeutic laser light from the distal end of the optical fiber toward a target site and receive return light at the distal end of the optical fiber; a sensor configured to spectroscopically measure the return light; and a processor circuit configured to: make a first determination from the spectroscopic measurement of the return light whether flashing event light is present in the return light, the flashing event light being generated when a flashing event occurs at the distal end of the optical fiber; and generate a flashing event data signal indicative of whether a flashing event has occurred in response to the first determination.

[0007] In one example, a method for operating a laser tissue ablation system may include illuminating a target site with visible light illumination having a visible light illumination spectrum using an illumination source disposed at a distal end of an endoscope body; capturing a video image of the illuminated target site using a video camera disposed at the distal end of the endoscope body; delivering therapeutic laser light from a distal end of an optical fiber extending distally from the distal end of the endoscope body toward the target site, the therapeutic laser light having at least one therapeutic laser light wavelength; receiving returned light at the distal end of the optical fiber; performing a spectroscopic measurement of the returned light to determine a measured light level in a detection spectral region that does not overlap with the visible light illumination spectrum and does not include the at least one therapeutic laser light wavelength; comparing, using a processor circuit, the measured light level to a threshold light level; determining, using the processor circuit, that the measured light level exceeds the threshold light level; and generating, using the processor circuit, a flushing event data signal indicating that a flushing event has occurred at the distal end of the optical fiber in response to determining that the measured light level exceeds the threshold light level.

[0008] In one example, a laser tissue ablation system includes an endoscope having an endoscopic body, an illumination source disposed at a distal end of the endoscopic body and configured to illuminate a target site with visible light illumination having a visible light illumination spectral range, a video camera disposed at the distal end of the endoscopic body and configured to capture video images of the illuminated target site, a video display configured to display the video images of the illuminated target site, and an optical fiber extending from the endoscopic body, the optical fiber delivering therapeutic laser light from a distal end of the optical fiber toward the target site, the therapeutic laser light having at least one therapeutic laser light wavelength, and receiving return light at the distal end of the optical fiber. a spectrometer configured to spectroscopically measure the returned light; and a processor circuit configured to: determine from the spectroscopic measurement of the returned light when a light level of the returned light at at least one flashing event wavelength rises above a threshold light level, the at least one flashing event wavelength being different from the at least one therapeutic laser light wavelength and outside the visible light illumination spectral range; and, in response to determining that the light level has risen above the threshold light level, generate a flashing event data signal indicating that a flashing event has occurred at the distal end of the optical fiber.

[0009] Various embodiments are illustrated by way of example in the accompanying drawing figures. Such embodiments are illustrative and are not intended to be exhaustive or exclusive embodiments of the present subject matter. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic side view of an example laser tissue ablation system. [Figure 2] 1 is a flowchart of an example method for operating a laser tissue ablation system. [Figure 3] 1 is a flowchart of an example method for operating a laser tissue ablation system. [Figure 4] FIG. 1 is a schematic diagram of an exemplary computer-based clinical decision support system (CDSS) configured to determine if or when a flushing event is occurring at the distal end of an optical fiber and, in response, take appropriate action, such as retracting the optical fiber proximally to stop the flushing event. DETAILED DESCRIPTION OF THE INVENTION

[0011] In a laser therapy treatment, a practitioner may position the distal end of an endoscope near a target, such as a kidney stone. The endoscope may include an optical fiber that can deliver therapeutic laser light to the target, such as through the distal end of the optical fiber. During treatment, it may be beneficial to dynamically monitor or dynamically control the separation between the distal end of the optical fiber and the target. For example, during a laser tissue ablation procedure, an operator may accidentally contact the distal end of the optical fiber with tissue while the laser is operating. If such contact occurs while the laser is operating, the contact may result in an event known as flashing. While flashing may not affect the effectiveness of the tissue ablation, it may degrade or degrade the distal end of the optical fiber. Such degradation may be known as fiber burnback.

[0012] Flushing is believed to be caused by the combustion of organic compounds within tissue, such as within kidney stones. Such combustion can produce light at wavelengths not produced by laser light sources. For example, laser light sources can produce laser light within wavelength ranges between about 1908 nm and about 2940 nm, or between about 1920 nm and 1960 nm. The light produced by a flushing event can have a wavelength that peaks at approximately 750 nm, with half-maximum intensity occurring at about 680 nm and about 840 nm.

[0013] Laser tissue ablation systems, described in detail below, can detect flashing events, such as by recognizing the spectroscopic profile (e.g., light intensity as a function of wavelength) of the flashing event. For example, the system can monitor light at one or more wavelengths outside the spectrum of light directed at the tissue. When the light at one or more wavelengths exceeds or rises above a specified threshold, the system can determine that a flashing event has begun. Thus, when the light level exceeds a specified threshold, the system can determine that a flashing event is currently occurring.

[0014] In response to detecting a flashing event, the system can take one or more actions. For example, the system can reposition the optical fiber so that the distal tip of the optical fiber is further away from the target. Recognizing such a flashing event and repositioning the optical fiber in response to the recognition of the flashing event can extend the life of the optical fiber, such as by reducing or eliminating fiber burnback. Other examples can include reducing the power of the laser light source, increasing the irrigation rate at or near the target, suppressing video images of the target, etc.

[0015] FIG. 1 shows a schematic side view of an example of a laser tissue ablation system 100. The laser tissue ablation system 100 may include an endoscope having an endoscopic body 102. The endoscopic body 102 may be grasped by an operator, who may position the endoscopic body 102 to observe and ablate one or more targets, such as kidney stones, at one or more internal locations of a patient, as needed. In some examples, the endoscopic body 102 may be rigid. In one or more examples, the endoscopic body 102 may be elongated along an elongation axis. The endoscopic body 102 may include one or more channels, passages, or openings extending through the endoscopic body 102 along the elongation axis. For example, the endoscopic body 102 may include a working channel. In some examples, an operator may perform suction through the working channel. In some examples, an operator may pass an instrument, such as a brush, biopsy needle, or forceps, through the working channel. In some examples, an operator may perform minimally invasive surgery through the working channel, such as to remove unwanted tissue or foreign matter from a patient's body. As another example, the endoscope body 102 may include an irrigation channel that can deliver irrigant to the target site to flush out debris from the target, etc. Other channels may also be used.

[0016] The laser tissue ablation system 100 can include an illumination light source 104 disposed at the distal end 106 of the endoscope body 102. For example, the illumination light source 104 can include one or more light-emitting diodes disposed at the distal end 106 of the endoscope body 102. In some examples, the light-emitting diodes can be white light-emitting diodes. For example, the white light-emitting diodes can include blue or violet light-emitting diodes combined with a phosphor that can absorb some or all of the blue or violet light and, in response, emit one or more longer wavelengths of light, such as in the yellow portion of the electromagnetic spectrum. Other illumination light sources can also be used. The illumination light source 104 can illuminate the target site 108 with visible light illumination having a visible light illumination spectral range. In some examples, the visible light illumination spectral range can include wavelengths in the visible portion of the electromagnetic spectrum.

[0017] The laser tissue ablation system 100 can include a video camera 110 disposed at the distal end 106 of the endoscope body 102. In some examples, the video camera 110 can include a lens, a sensor element disposed at the focal plane of the lens, and electronics capable of converting an electrical signal generated by the sensor element into a digital signal. The video camera element can be disposed in a relatively small, sealed package at the distal end 106 of the endoscope body 102. The video camera 110 can capture real-time video images of the illuminated target site 108.

[0018] The laser tissue ablation system 100 can include a video display 112 capable of displaying a video image of the illuminated target site 108. For example, the video display 112 can be mounted on or in an equipment rack separate from the endoscope. The video display 112 can provide the practitioner with a real-time image of the target site 108 illuminated with white light from the illumination source 104.

[0019] The laser tissue ablation system 100 can include a laser light source 114 capable of generating laser light, such as pulsed laser light. The laser light source 114 can be positioned remotely from the endoscope body 102 so that the endoscope 102 can be positionable by an operator, or the laser light source 114 can be disposed within a laser housing that can remain in a fixed position spaced apart from the endoscope body 102 during a procedure. In some examples, the laser light source 114 can include a thulium fiber laser capable of generating light having one or more wavelengths between about 1920 nm and about 1960 nm. In some examples, the laser light source 114 can include a thulium:YAG (yttrium aluminum garnet) laser capable of generating light at a wavelength of 2010 nm. In some examples, the laser light source 114 can include a holmium:YAG laser capable of generating light at a wavelength of 2120 nm. In some examples, the laser light source 114 can include an erbium:YAG laser capable of generating light at a wavelength of 2940 nm. In some examples, the laser light generated by the laser light source 114 can include a first wavelength, such as between about 1908 nm and about 2940 nm, or between about 1920 nm and 1960 nm, between about 1900 nm and about 1940 nm, greater than about 1900 nm, greater than about 1800 nm, or other wavelengths. For these (and other) laser light sources, the laser light can have a wavelength in a portion of the electromagnetic spectrum where water (a major component of tissue) has relatively high absorption. During treatment, tissue can absorb the laser light, heat locally to relatively high temperatures, and decompose due to localized thermal strain within the tissue.

[0020] The laser tissue ablation system 100 can include an optical fiber 116 that can extend from the endoscope body 102. In some examples, the optical fiber 116 can be a multimode optical fiber. In some examples, the optical fiber 116 can have a distal end 118 that extends from the distal end 106 of the endoscope body 102.

[0021] The laser source 114 can direct laser light into a proximal portion 120 of the optical fiber 116, such as via a laser source optical fiber 122 and a free-space optical coupler / splitter 124. The free-space optical coupler / splitter 124 can include a collimating lens 126 with a focal plane located at a distal end 128 of the laser source optical fiber 122, which can collimate (or at least partially focus) the light from the laser source 114. The collimated light can pass through a beam splitter 130 and be focused onto the proximal portion 120 of the optical fiber 116 by a bidirectional focusing lens 132. The bidirectional focusing lens 132 can collimate the return light that travels back through the optical fiber 116. The beam splitter 130 can direct all or a portion (or spectral portion) of the returning light onto a return path focusing lens 134, which can focus the returning light onto an end 136 of a return path optical fiber 138. The return path optical fiber 138 can direct the returning light to a sensor (described below). The free-space optical coupler / splitter 124 is just one configuration for such a coupler / splitter. Alternatively, a fiber-based optical coupler / splitter can also be used.

[0022] The optical fiber 116 can direct the laser light distally along the length of the optical fiber 116 to emerge from a distal end 118 of the optical fiber 116 to form a therapeutic laser light. The optical fiber 116 can deliver the therapeutic laser light from the distal end 118 of the optical fiber 116 toward the target site 108. The therapeutic laser light can include at least one therapeutic laser light wavelength, such as between about 1908 nm and about 2940 nm, or between about 1920 nm and 1960 nm, between about 1900 nm and about 1940 nm, greater than about 1900 nm, greater than about 1800 nm, or other suitable wavelength.

[0023] The optical fiber 116 can receive the return light at the distal end 118 of the optical fiber 116. In some examples, the return light can include at least a portion of the therapeutic laser light reflected from the target site 108. When a flashing event occurs, the return light can additionally include flashing event light. The flashing event light can have a spectral profile that is different from the spectral profile of the therapeutic laser light. In other words, the flashing event light can be spectrally separated from the therapeutic laser light. For example, the flashing event light can have a spectral profile that peaks at approximately 750 nm and has half-maximum optical intensity at about 680 nm and about 840 nm. In some examples, the flashing event light can have a spectral profile that includes wavelengths shorter than one or more wavelengths of the therapeutic laser light.

[0024] The laser tissue ablation system 100 can include a sensor 140 capable of measuring the return light spectroscopically. For example, the sensor 140 can measure the return light at one or more specified wavelengths or wavelength regions. The specified wavelengths or wavelength regions may not be present in the spectrum of the illumination light and may differ from the one or more wavelengths of the therapeutic laser light. In other words, the sensor 140 can measure the return light at one or more wavelengths that are not directed from the endoscope to the target site 108. In some examples, the sensor 140 can filter out one or more wavelength regions and detect one or more of the remaining wavelength regions that are not filtered out.

[0025] The sensor 140 may include a photosensitive sensor element 142 capable of converting an optical signal, such as returned light, into an internal electrical signal. The sensor 140 may also include sensor circuitry 144, as shown in the configuration of FIG. 1, which may convert or process the internal electrical signal from the photosensitive sensor element 142 into an analog or digital sensor data signal 146 that can be interpreted by a processor circuitry 148 (described below). The sensor 140 may further include one or more wavelength-sensitive elements, which enable the sensor circuitry 144 to provide intensity measurements of the returned light as a function of wavelength.

[0026] For example, the wavelength-sensitive element of the sensor 140 can include a dichroic beam splitter (e.g., implemented as a thin-film coating on the beam splitter 130) that can separate the flashing event light (e.g., having a wavelength between about 680 nm and about 840 nm) from the therapeutic laser light (e.g., having one or more wavelengths between about 1900 nm and about 1940 nm). The dichroic beam splitter can have a threshold wavelength and can direct light having wavelengths shorter than the threshold wavelength along a first optical path and light having wavelengths longer than the threshold wavelength along a second optical path. The threshold wavelength can have any suitable wavelength value between the spectral profile of the flashing event light and the wavelength of the therapeutic laser light wavelength. For example, the threshold wavelength can be 1000 nm, 1500 nm, 1700 nm, or any other suitable value. In some examples, the dichroic beam splitter can be implemented as a thin-film coating on the surface of a transparent optical element such as a prism.

[0027] In some configurations, the sensor 140 may include a dichroic beam splitter (e.g., implemented as a thin-film coating on the beam splitter 130) that can receive the returned light, direct the therapeutic laser light along a first optical path, and direct the flashing event light along a second optical path. The photosensitive sensor element 142 of the sensor 140 may include a sensor element or detector that can detect light from the second optical path. Such a sensor can detect a flash event as the presence (or increase) of a signal generated by the sensor 140. In some examples, the photosensitive sensor element 142 may include a single detector element. In other examples, the photosensitive sensor element 142 may include a multi-pixel detector element. The sensor 140 may further include a sensor circuit 144 that can generate one or more sensor data signals 146 in response to the light received by the optical sensor. A processor circuit 148 (described below) can analyze the one or more sensor data signals 146 to determine whether and / or when a flashing event occurred.

[0028] In some configurations, the sensor circuit 144 of the sensor 140 (and optionally, the wavelength-sensitive element of the sensor 140) can include a spectrometer that can measure the returning light spectroscopically. For these configurations, the photosensitive sensor element 142 can include a spectrometer sensor or spectrometer detector that can receive all or a portion of the returning light. For these configurations, the sensor data signal 146 can be a spectrometer output signal that includes data representing light intensity (or amplitude, or other suitable photometric quantity) as a function of wavelength. The processor circuit 148 (described below) can analyze the spectrometer output signal to determine whether and / or when a flashing event has occurred.

[0029] For configurations in which sensor 140 includes a spectrometer, laser tissue ablation system 100 can optionally perform an analysis of the target based on the returned light. For example, spectrometer and processor circuit 148 can use the flashing event light to generate a spectroscopic profile of target site 108. In some examples, processor circuit 148 (described below) can use the spectroscopic profile of target site 108 to determine the material composition of target site 108, such as by matching the measured spectroscopic profile of target site 108 with one or more of a specified (finite) number of predetermined spectroscopic profiles corresponding to known materials. These are merely examples, and other suitable analyses of target site 108 can be performed.

[0030] The laser tissue ablation system 100 may include a processor circuit. In some examples, the processor circuit 148 may be referred to as a controller. In some examples, the processor circuit 148 may be implemented purely in software. In some examples, the processor circuit 148 may be implemented purely in hardware. In some examples, the processor circuit 148 may be implemented as a combination of software and hardware. In some examples, the processor circuit 148 may be implemented on a single processor. In some examples, the processor circuit 148 may be implemented on multiple processors. In some examples, the multiple processors may be housed within a common housing. In some examples, at least two of the multiple processors may be spaced apart within different housings.

[0031] The processor circuit 148 can analyze one or more signals generated by the sensor 140, such as the sensor data signal 146 or the spectrometer output signal, to determine whether and / or when a flushing event occurred.

[0032] For example, the processor circuit 148 can make a first determination from a spectroscopic measurement of the returned light whether flashing event light is present in the returned light. The flashing event light can be generated when a flashing event occurs at the distal end 118 of the optical fiber 116. In response to the first determination, the processor circuit 148 can generate a flashing event data signal indicating whether a flashing event occurred.

[0033] As another example, where spectroscopic measurements of the returned light determine a measured light level in a detection spectral region that does not overlap with the visible light illumination spectrum and does not include at least one therapeutic laser light wavelength, the processor circuit 148 can compare the measured light level to a threshold light level, such as a value stored on a server or in a look-up table. The processor circuit 148 can determine if and / or when the measured light level exceeds the threshold light level. In response to determining that the measured light level exceeds the threshold light level, the processor circuit 148 can generate a flushing event data signal indicating that a flushing event has occurred at the distal end 118 of the optical fiber 116.

[0034] As another example, the processor circuit 148 can determine from spectroscopic measurements of the returned light when the light level of the returned light at at least one flashing event wavelength rises above a threshold light level. The at least one flashing event wavelength may be different from the at least one therapeutic laser light wavelength and may be outside the visible light illumination spectrum. In response to determining that the light level has risen above the threshold light level, the processor circuit 148 can generate a flashing event data signal indicating that a flashing event has occurred at the distal end 118 of the optical fiber 116.

[0035] In some examples, the threshold light level may be constant (e.g., unchanging) over time. In some examples, the threshold light level may vary over time, such as varying with the output power of the laser light source 114. The processor circuit 148 may use other suitable signal analysis techniques to determine that a flashing event has occurred.

[0036] In some examples, the free-space optical coupler / splitter 124, the sensor 140, and the processing circuitry 148 can be contained within a housing 150. The laser source 114 can direct laser light into the housing via a laser source optical fiber 122. An optical fiber 116 can direct the laser light from the housing 150 to the endoscope body 102 and tether the endoscope to the housing 150. The video display 112 can optionally be attached to or integrated with the housing 150.

[0037] When the processor circuit 148 determines that a flushing event has occurred, the processor circuit 148 can generate an action. For example, in response to a first determination (e.g., that a flushing event has occurred), the processor circuit 148 can generate a flushing event data signal indicating whether a flushing event has occurred. In some examples, the flushing event data signal can be an electrical signal. For example, the flushing event data signal can have a first voltage if a flushing event does not occur and a second voltage if a flushing event occurs. In some examples, the flushing event data signal can be a digital signal. For example, the flushing event data signal can include a variable stored in memory. The variable can have a first value if a flushing event does not occur and a second value if a flushing event occurs. Other suitable flushing event data signals can also be used.

[0038] One example of an action (taken in response to determining that a flushing event has occurred) is retracting the optical fiber 116 proximally to terminate the flushing event (e.g., to increase the distance (Z) in FIG. 1 ). For example, the laser tissue ablation system 100 can further include an actuator 152 that can automatically retract the optical fiber 116 proximally relative to the endoscope body 102 in response to receiving data corresponding to the flushing event data signal. In some examples, as in the configuration of FIG. 1 , the actuator 152 can include a wheel. The wheel can have a center that is fixed in position relative to the endoscope body 102. The wheel can have a circumferential surface that contacts the optical fiber 116. The wheel can be rotatable from a rotary actuator, such as a rotary actuator located at or near the center of the wheel. In some examples, the actuator 152 can automatically retract the optical fiber 116 proximally relative to the endoscope body 102 a specified distance in response to receiving data corresponding to the flushing event data signal. The specified distance can be sufficient to terminate the flushing event, such as 1 mm, approximately 1 mm, or any other suitable value. 1 is just one example of an actuator that can retract the optical fiber 116 proximally to terminate a flushing event. Other suitable actuators can also be used.

[0039] Another example of an action (taken in response to determining that a flashing event has occurred) is causing laser source 114 to reduce its output power, optionally to zero.

[0040] Another example of an action (taken in response to determining that a flushing event has occurred) is supplying more irrigant to the target site 108. For example, the laser tissue ablation system 100 may include an irrigation regulator 154 coupled to the endoscope. The irrigation regulator 154 may supply an irrigant, such as saline, to the target site 108 at a controllable irrigation rate via an irrigation line 156. The processor circuit 148 may instruct the irrigation regulator 154 to increase the irrigation rate in response to receiving data corresponding to the flushing event data signal.

[0041] Another example of an action (taken in response to determining that a flashing event has occurred) is suppressing or ceasing the displayed video image of the target site 108. For example, the laser tissue ablation system 100 may include an illumination source 104 disposed at the distal end 106 of the endoscope body 102. The illumination source 104 may illuminate the target site 108 with visible illumination. The laser tissue ablation system 100 may include a video camera 110 disposed at the distal end 106 of the endoscope body 102. The video camera 110 may capture a video image of the illuminated target site 108. The laser tissue ablation system 100 may include a video display 112 coupled to the processor circuit 148. The video display 112 may display the video image of the illuminated target site 108. The processor circuit 148 may suppress the video image in response to receiving data corresponding to the flashing event data signal such that the video display 112 does not display the video image when a flashing event is occurring. The examples of actions taken in response to determining that a flushing event has occurred are merely examples, and the processing circuitry may alternatively take other suitable actions.

[0042] In some examples, the processor circuit 148 can optionally determine when or whether the flashing event has stopped and can optionally take additional action in response to determining that the flashing event has stopped. For example, the processing circuit 148 can make a second determination that the flashing event has stopped from a spectroscopic measurement of the returned light that indicates that the flashing event light is no longer present in the returned light. In response to making the second determination, the processor circuit 148 can resume displaying the video image on the video display 112. Other appropriate action can also be taken, such as causing the laser light source 114 to optionally increase its output power to the previous output power level utilized before the processor circuit 148 determined that a flashing event was occurring.

[0043] In some examples, the processor circuit 148 may take action after the processor circuit 148 detects a specified number of flashing events within a specified time interval. In some examples, the processor circuit 148 may take action after the processor circuit 148 detects a specified number of flashing events in a specified number of consecutive laser pulses. Other criteria may be used.

[0044] Figure 2 shows a flowchart of an example method 200 for operating a laser tissue ablation system, such as laser tissue ablation system 100 of Figure 1 or any other suitable laser tissue ablation system. Method 200 is only one example method for operating a laser tissue ablation system, and other methods can be used.

[0045] In operation 202, an optical fiber including a distal end extendable from an endoscope body of an endoscope can deliver therapeutic laser light from the distal end of the optical fiber toward a target site.

[0046] In operation 204, the optical fiber can receive the returning light at the distal end of the optical fiber.

[0047] In operation 206, a sensor can measure the returning light spectroscopically.

[0048] In operation 208, the processor circuit may make a first determination from the spectroscopic measurement of the returned light whether flashing event light is present in the returned light. The flashing event light may be generated when a flashing event occurs at the distal end of the optical fiber.

[0049] At operation 210, the processor circuit may generate a flushing event data signal in response to the first determination that indicates whether a flushing event has occurred.

[0050] Figure 3 shows a flowchart of an example method 300 for operating a laser tissue ablation system, such as laser tissue ablation system 100 of Figure 1 or any other suitable laser tissue ablation system. Method 300 is only one example of a method for operating a laser tissue ablation system, and other methods can be used.

[0051] In operation 302, an illumination source located at the distal end of the endoscope body can illuminate a target site with visible light illumination having a visible light illumination spectrum.

[0052] In operation 304, a video camera located at the distal end of the endoscope body can capture a video image of the illuminated target site.

[0053] In operation 306, an optical fiber extending distally from the distal end of the endoscope body can deliver therapeutic laser light from the distal end of the optical fiber toward the target site. The therapeutic laser light can have at least one therapeutic laser light wavelength.

[0054] In operation 308, the optical fiber can receive the returning light at the distal end of the optical fiber.

[0055] In operation 310, the laser tissue ablation system can perform spectroscopic measurements of the returned light to determine measured light levels in a detection spectral region that does not overlap with the visible light illumination spectrum and does not include at least one therapeutic laser light wavelength.

[0056] In operation 312, the processor circuit may compare the measured light level to a threshold light level.

[0057] In operation 314, the processor circuit may determine that the measured light level exceeds the threshold light level.

[0058] At operation 316, the processor circuit may generate a flushing event data signal indicating that a flushing event has occurred at the distal end of the optical fiber in response to determining that the measured light level exceeds the threshold light level.

[0059] In some examples, method 300 can optionally further include, using the processor circuitry, causing the actuator to retract the optical fiber proximally relative to the endoscope body a specified distance in response to determining that the measured light level exceeds a threshold light level, the specified distance being sufficient to terminate the flushing event.

[0060] In some examples, method 300 may optionally further include displaying a video image of the illuminated target area on a video display coupled to the processor circuit, and using the processor circuit to suppress the video image in response to determining that the measured light level exceeds a threshold light level such that the video display does not display the video image when a flashing event is occurring.

[0061] In some examples, method 300 may optionally further include using an irrigation regulator coupled to the endoscope to deliver irrigant to the target site at a controllable irrigation rate, and using the irrigation regulator to increase the irrigation rate in response to determining that the measured light level exceeds a threshold light level.

[0062] 4 shows a schematic diagram of an exemplary computer-based clinical decision support system (CDSS) 400 configured to determine whether or when a flushing event is occurring at the distal end of the optical fiber and, in response, take appropriate action, such as retracting the optical fiber proximally, to stop the flushing event. In various embodiments, the CDSS 400 includes an input interface 402 through which the sensor data signal 146 can be provided as an input feature to an artificial intelligence (AI) model 404, a processor such as a controller, or processor circuitry 148 that performs inference operations from which a determination of whether and / or when a flushing event occurred is communicated to a user, e.g., a clinician.

[0063] In some embodiments, the input interface 402 may be a direct data link between the CDSS 400 and one or more medical devices, such as the laser tissue ablation system 100 or an endoscope, that generate at least a portion of the input features. For example, the input interface 402 may transmit decisions directly to the CDSS during a therapeutic and / or diagnostic medical procedure. Additionally or alternatively, the input interface 402 may be a classic user interface that facilitates interaction between a user and the CDSS 400. For example, the input interface 402 may facilitate a user interface through which a user may manually input decisions. Additionally or alternatively, the input interface 402 may provide the CDSS 400 with access to an electronic patient record from which one or more input features may be extracted. In any of these cases, the input interface 402 is configured to collect decisions associated with a particular patient at or before the time the CDSS 400 is used to evaluate a medical condition addressed by the laser tissue ablation system 100 or an endoscope, such as a kidney stone.

[0064] Based on one or more of the above input features, the controller or processor circuitry 148 performs an inference operation using an AI model to generate a decision. For example, the input interface 402 can deliver the sensor data signal 146 to an input layer of the AI ​​model, which propagates the input features through the AI ​​model to an output layer. An AI model can provide a computer system with the ability to perform tasks without being explicitly programmed by making inferences based on patterns discovered in analyzing data. AI models explore the study and construction of algorithms (e.g., machine learning algorithms) that can learn from existing data and make predictions about new data. Such algorithms operate by building an AI model from example training data to make data-driven predictions or decisions, which are expressed as outputs or evaluations.

[0065] There are two general modes of machine learning (ML): supervised and unsupervised. Supervised ML uses prior knowledge (e.g., examples that associate inputs with outputs or outcomes) to learn relationships between inputs and outputs. The goal of supervised ML is to learn a function that best approximates the relationship between training inputs and outputs, given some training data, so that the ML model can implement the same relationship when given the input to generate the corresponding output. Unsupervised ML is the training of an ML algorithm using unclassified or unlabeled information, allowing the algorithm to act on that information without guidance. Unsupervised ML is useful in exploratory analysis because it can automatically identify structure in data.

[0066] Common tasks for supervised ML are classification and regression problems. Classification problems, also called categorization problems, aim to classify an item into one of several categorical values ​​(e.g., is this object an apple or an orange?). Regression algorithms aim to quantify some items (e.g., by providing a score for the value of some input). Some examples of commonly used supervised ML algorithms are logistic regression (LR), naive Bayes, random forest (RF), neural networks (NN), deep neural networks (DNN), matrix decomposition, and support vector machines (SVM).

[0067] Some common tasks for unsupervised ML include clustering, representation learning, and density estimation. Some examples of commonly used unsupervised ML algorithms are k-means clustering, principal component analysis, and autoencoders.

[0068] Another type of ML is federated learning (also known as collaborative learning), which trains algorithms across multiple distributed devices that hold local data without exchanging data. This approach contrasts with traditional centralized machine learning techniques, where all local datasets are uploaded to a single server, as well as more classical distributed approaches that often assume local data samples are identically distributed. Federated learning allows multiple actors to build a common, robust machine learning model without sharing data, thus addressing important issues such as data privacy, data security, data access rights, and access to heterogeneous data.

[0069] In some examples, the AI ​​model may be continuously or periodically trained prior to execution of an inference operation by the controller or processor circuitry 148. Then, during the inference operation, patient-specific input features provided to the AI ​​model may be propagated from an input layer, through one or more hidden layers, and ultimately to an output layer corresponding to a distance (Z) value.

[0070] In some examples, the AI ​​model can include a database that can include data corresponding to the patient. The database can provide the patient record to the CDSS 400. In some examples, the AI ​​model can receive sensor data signals 146 from a sensor, such as sensor 140.

[0071] During and / or following the inference operation, the determination may be communicated to a user via a user interface (UI) and / or may cause an actuator or alarm connected to the processor to automatically perform a desired action. For example, the controller or processor circuitry 148 may cause an actuator to move an optical fiber relative to the endoscope. Alternatively, the controller or processor circuitry 148 may cause an alarm to alert a practitioner.

[0072] In some examples, the CDSS 400 may optionally be used to determine actions to be taken in response to the sensor data signal 146 .

[0073] Some features described herein may provide methods and devices that can distinguish between various target compositions, for example, in endoscopic in vivo medical applications (e.g., hard or soft tissue). This may allow an operator to continuously monitor the composition of the target viewed through the endoscope throughout the procedure. This may also be used in conjunction with a laser system, in which case the method may provide feedback to the laser system to adjust settings based on the target composition. This feature may allow for instantaneous adjustment of laser settings within the setting range of the original laser settings selected by the operator.

[0074] Some features described herein can be used to provide systems and methods that measure differences in the chemical composition of a target in vivo and suggest or automatically adjust laser settings to better achieve a desired effect. Examples of targets and applications include laser lithotripsy of kidney stones and laser ablation or vaporization of soft tissue. In one example, three major components are provided: a laser, a spectroscopy system, and a feedback analyzer. In one example, a laser system controller can automatically program laser treatment with appropriate laser parameter settings based on the target composition. In one example, the laser can be controlled based on a machine learning algorithm trained using spectroscopy data. Additionally or alternatively, the operator can continuously receive indications of target type during treatment and be prompted to adjust laser settings. By adjusting laser settings and adapting laser treatment to the compositional components of a single stone target, stone ablation or dusting procedures can be performed faster and more energy-efficiently.

[0075] Some features described herein may provide systems and methods for providing data input to a feedback analyzer, including internet connectivity and connectivity to other surgical devices with measurement capabilities. In addition, the laser system may provide input data to another system, such as an image processor, so that a treatment monitor can display information related to the medical treatment to the operator. One example of this is more clearly distinguishing between different soft tissues, vasculature, overlying tissues, and different chemical compositions within the same target, such as a stone, within the field of view during treatment.

[0076] Some features described herein may provide systems and methods for identifying different target types, such as different tissue types or different stone types. In some cases, a single stone structure (e.g., a kidney stone, bladder stone, pancreaticobiliary stone, or gallbladder stone) may have two or more different compositions throughout its volume, such as brushite, calcium phosphate (CaP), calcium oxalate dihydrate (COD), calcium oxalate monohydrate (COM), ammonium magnesium phosphate (MAP), or a cholesterol- or uric acid-based stone structure. For example, the target stone structure may include a first portion of COD and a second portion of COM. According to one aspect, this document describes systems and methods for continuously identifying different compositions contained within a single target (e.g., a single stone) based on continuous collection and analysis of in vivo spectroscopic data. Treatment (e.g., laser therapy) may be adapted according to the identified target composition. For example, in response to identifying a first composition (e.g., COD) within a target stone, the laser system may be programmed with a first laser parameter setting (e.g., power, exposure time, or launch angle, etc.) and deliver a laser beam accordingly to ablate or pulverize the first portion. Spectroscopic data may be continuously collected and analyzed during laser treatment. In response to identifying a second composition (e.g., COM) within the same target stone being treated that is different from the first composition, the laser treatment may be adjusted, such as by programming the laser system with a second laser parameter setting (e.g., different power, exposure time, or launch angle, etc.) that is different from the first laser parameter setting, and deliver a laser beam accordingly to ablate or pulverize the second portion of the same target stone. In some examples, multiple different laser sources may be included within the laser system. Stone portions of different compositions may be treated by different laser sources. The appropriate laser to use may be determined by identifying the stone type.

[0077] Some features described herein may be used in connection with laser systems for various applications where incorporating different types of laser sources may be advantageous. For example, the features described herein may be suitable in industrial or medical settings, such as medical diagnostics, treatments, and surgical procedures. The features described herein may be used in connection with endoscopy, laser surgery, laser lithotripsy, laser settings, and / or spectroscopy.

[0078] In the foregoing detailed description, the method and apparatus of the present disclosure have been described with reference to specific embodiments thereof. It will, however, be apparent that various modifications and changes may be made thereto without departing from the broader spirit and scope of the present disclosure. The present specification and figures are therefore to be regarded as illustrative rather than restrictive.

[0079] To further illustrate the devices and related methods disclosed herein, a non-limiting list of examples is provided below. Each of the following non-limiting examples can stand alone or can be combined with any one or more of the other examples in any permutation or combination.

[0080] In Example 1, a laser tissue ablation system can include an optical fiber including a distal end extendable from an endoscopic body of an endoscope, the optical fiber configured to deliver therapeutic laser light from the distal end of the optical fiber toward a target site and receive returning light at the distal end of the optical fiber; a sensor configured to spectroscopically measure the returning light; and a processor circuit configured to: make a first determination from the spectroscopic measurement of the returning light whether flashing event light is present in the returning light, the flashing event light being generated when a flashing event occurs at the distal end of the optical fiber; and generate a flashing event data signal indicative of whether a flashing event occurred in response to the first determination.

[0081] In Example 2, the laser tissue ablation system of Example 1 can be optionally configured such that the flashing event light is spectrally separated from the therapeutic laser light.

[0082] In Example 3, the laser tissue ablation system of any one of Examples 1-2 can be optionally configured such that the therapeutic laser light includes a first wavelength and the flashing event light has a spectral profile that includes wavelengths shorter than the first wavelength.

[0083] In Example 4, the laser tissue ablation system of any one of Examples 1-3 can optionally further include an actuator controllable by the processor circuit, the actuator configured to automatically retract the optical fiber proximally relative to the endoscope body a specified distance in response to a first determination, the specified distance being sufficient to terminate the flushing event.

[0084] In Example 5, the laser tissue ablation system of any one of Examples 1 to 4 can optionally be configured such that the actuator comprises a wheel, the wheel having a center fixed in position relative to the endoscope body, the wheel having a circumferential surface in contact with the optical fiber, and the wheel rotatable from a rotary actuator controllable by the processor circuit.

[0085] In Example 6, the laser tissue ablation system of any one of Examples 1-5 can optionally further include an illumination light source disposed at the distal end of the endoscope body and configured to illuminate the target site with visible illumination; a video camera disposed at the distal end of the endoscope body and configured to capture video images of the illuminated target site; and a video display coupled to the processor circuit and configured to display the video images of the illuminated target site, wherein the processor circuit is further configured to suppress the video images in response to the first determination such that the video display does not display the video images when a flashing event is occurring.

[0086] In Example 7, the laser tissue ablation system of any one of Examples 1-6 can be optionally configured such that the processor circuit is further configured to make a second determination that the flashing event has stopped from a spectroscopic measurement of the returned light indicating that flashing event light is no longer present in the returned light, and in response to making the second determination, resume displaying the video image on the video display.

[0087] In Example 8, the laser tissue ablation system of any one of Examples 1-7 can optionally further include an irrigation regulator coupled to the endoscope and configured to deliver irrigant to the target site at a controllable irrigation rate, the irrigation regulator further configured to increase the irrigation rate in response to receiving data corresponding to the flushing event data signal.

[0088] In Example 9, the laser tissue ablation system of any one of Examples 1-8 can be optionally configured such that the sensor comprises a spectrometer.

[0089] In Example 10, the laser tissue ablation system of any one of Examples 1-9 can be optionally configured such that the spectrometer and processor circuitry is further configured to use the flashing event light to generate a spectroscopic profile of the target site.

[0090] In Example 11, the laser tissue ablation system of any one of Examples 1-10 can be optionally configured such that the processor circuitry is further configured to use the spectroscopic profile of the target site to determine a material composition of the target site.

[0091] In Example 12, the laser tissue ablation system of any one of Examples 1-11 can be optionally configured such that the sensor comprises a dichroic beam splitter configured to receive the return light and direct the therapeutic laser light along a first optical path and direct the flashing event light along a second optical path, and an optical sensor configured to detect light from the second optical path.

[0092] In Example 13, a method for operating a laser tissue ablation system includes illuminating a target site with visible light illumination having a visible light illumination spectrum using an illumination source disposed at a distal end of an endoscope body; capturing a video image of the illuminated target site using a video camera disposed at the distal end of the endoscope body; delivering therapeutic laser light from a distal end of an optical fiber extending distally from the distal end of the endoscope body toward the target site, the therapeutic laser light having at least one therapeutic laser light wavelength; receiving returned light at the distal end of the optical fiber; performing a spectroscopic measurement of the returned light to determine a measured light level in a detection spectral region that does not overlap with the visible light illumination spectrum and does not include the at least one therapeutic laser light wavelength; comparing, using a processor circuit, the measured light level to a threshold light level; determining, using the processor circuit, that the measured light level exceeds the threshold light level; and generating, using the processor circuit, a flushing event data signal indicating that a flushing event has occurred at the distal end of the optical fiber in response to determining that the measured light level exceeds the threshold light level.

[0093] In Example 14, the method of Example 13 can optionally further include the step of causing, using the processor circuitry, the actuator to automatically retract the optical fiber proximally relative to the endoscope body a specified distance in response to determining that the measured light level exceeds a threshold light level, wherein the specified distance is sufficient to terminate the flushing event.

[0094] In Example 15, the method of any one of Examples 13-14 can optionally further include displaying a video image of the illuminated target area on a video display coupled to the processor circuit; and suppressing, using the processor circuit, the video image in response to determining that the measured light level exceeds a threshold light level such that the video display does not display the video image when a flashing event is occurring.

[0095] In Example 16, the method of any one of Examples 13-15 can optionally further include using an irrigation regulator coupled to the endoscope to supply irrigant to the target site at a controllable irrigation rate, and using the irrigation regulator to increase the irrigation rate in response to determining that the measured light level exceeds a threshold light level.

[0096] In Example 17, a laser tissue ablation system includes an endoscope having an endoscopic body; an illumination source disposed at a distal end of the endoscopic body and configured to illuminate a target site with visible light illumination having a visible light illumination spectral range; a video camera disposed at the distal end of the endoscopic body and configured to capture video images of the illuminated target site; a video display configured to display the video images of the illuminated target site; and an optical fiber extending from the endoscopic body, the optical fiber delivering therapeutic laser light from a distal end of the optical fiber toward the target site, the therapeutic laser light having at least one therapeutic laser light wavelength; and receiving return light at the distal end of the optical fiber. a spectrometer configured to spectroscopically measure the returned light; and a processor circuit configured to: determine from the spectroscopic measurement of the returned light when a light level of the returned light at at least one flashing event wavelength rises above a threshold light level, the at least one flashing event wavelength being different from the at least one therapeutic laser light wavelength and outside the visible light illumination spectral range; and, in response to determining that the light level has risen above the threshold light level, generate a flashing event data signal indicating that a flashing event has occurred at the distal end of the optical fiber.

[0097] In Example 18, the laser tissue ablation system of Example 17 can optionally further include an actuator controllable by the processor circuit, the actuator configured to automatically retract the optical fiber proximally relative to the endoscope body a specified distance in response to determining that the light level has risen above a threshold light level, the specified distance being sufficient to terminate the flushing event.

[0098] In Example 19, the laser tissue ablation system of any one of Examples 17-18 can be optionally configured such that the processor circuit is further configured to suppress the video image in response to determining that the light level has risen above a threshold light level such that the video display does not display a video image when a flashing event is occurring.

[0099] In Example 20, the laser tissue ablation system of any one of Examples 17-19 can optionally further comprise an irrigation regulator coupled to the endoscope and configured to supply irrigant to the target site at a controllable irrigation rate, and the processor circuitry is further configured to increase the irrigation rate in response to determining that the light level has risen above a threshold light level. [Explanation of symbols]

[0100] 100 Laser Tissue Ablation System 102 Endoscope body 104 Light source 106 Distal end 108 Target site 110 Video Camera 112 Video Display 114 Laser light source 116 Optical Fiber 118 Distal end 120 proximal part 122 Laser light source optical fiber 124 Free Space Optical Coupler / Splitter 126 Collimating Lens 128 Distal End 130 Beam Splitter 132 Bidirectional focusing lens 134 Return path focusing lens 136 edge 138 Return path optical fiber 140 sensors 142 Photosensitive sensor element 144 Sensor Circuit 146 Analog or digital sensor data signals, sensor data signals 148 Processor Circuit 150 Housing 152 Actuator 154 Irrigation regulator 156 Irrigation Line 400 Computer-based Clinical Decision Support System (CDSS), CDSS 402 Input Interface 404 Artificial Intelligence (AI) Model

Claims

1. 1. An optical fiber including a distal end extendable from an endoscope body of an endoscope, the optical fiber comprising: delivering therapeutic laser light from the distal end of the optical fiber toward a target site; configured to receive returning light at the distal end of the optical fiber; An optical fiber; a sensor configured to spectroscopically measure the returned light; 1. A processor circuit, comprising: making a first determination from a spectroscopic measurement of the returned light whether flashing event light is present in the returned light, the flashing event light being generated when a flashing event occurs at the distal end of the optical fiber; generating a flushing event data signal in response to the first determination, the flushing event indicating whether the flushing event has occurred; a processor circuit configured to: an actuator controllable by the processor circuit, the actuator configured to automatically retract the optical fiber proximally relative to the endoscope body a specified distance in response to the first determination, the specified distance being sufficient to terminate the flushing event; and 1. A laser tissue ablation system comprising:

2. The laser tissue ablation system of claim 1 , wherein the flashing event light is spectrally separated from the therapeutic laser light.

3. the therapeutic laser light comprises a first wavelength; the flashing event light has a spectral profile that includes wavelengths shorter than the first wavelength. The laser tissue ablation system of claim 1 .

4. 2. The laser tissue ablation system of claim 1, wherein the actuator comprises a wheel, the wheel having a center fixed in position relative to the endoscope body, the wheel having a circumferential surface in contact with the optical fiber, the wheel being rotatable from a rotary actuator controllable by the processor circuit.

5. an illumination source disposed at a distal end of the endoscope body and configured to illuminate the target site with visible illumination; a video camera disposed at the distal end of the endoscope body and configured to capture video images of the illuminated target area; a video display coupled to the processor circuit and configured to display the video image of the illuminated target area; Furthermore, the processor circuitry is further configured to suppress the video image in response to the first determination such that the video display does not display the video image when the flashing event occurs. The laser tissue ablation system of claim 1 .

6. the processor circuitry comprises: making a second determination that the flashing event has stopped from a spectroscopic measurement of the returned light indicating that the flashing event light is no longer present in the returned light; Responsive to making the second determination, resuming displaying the video image on the video display.

6. The laser tissue ablation system of claim 5, further configured to:

7. 10. The laser tissue ablation system of claim 1, further comprising: an irrigation regulator coupled to the endoscope and configured to supply irrigant to the target site at a controllable irrigation rate, the irrigation regulator further configured to increase the irrigation rate in response to receiving data corresponding to the flushing event data signal.

8. The laser tissue ablation system of claim 1 , wherein the sensor comprises a spectrometer.

9. 10. The laser tissue ablation system of claim 8, wherein the spectrometer and the processor circuitry are further configured to use the flashing event light to generate a spectroscopic profile of the target region.

10. 10. The laser tissue ablation system of claim 9, wherein the processor circuitry is further configured to use the spectroscopic profile of the target site to determine a material composition of the target site.

11. The sensor a dichroic beam splitter configured to receive the return light, direct the treatment laser light along a first optical path, and direct the flashing event light along a second optical path; an optical sensor configured to detect light from the second optical path; 10. The laser tissue ablation system of claim 1, comprising:

12. 1. A method for operating a laser tissue ablation system, the method comprising: illuminating the target site with visible light illumination having a visible light illumination spectrum using an illumination source disposed at the distal end of the endoscope body; capturing a video image of the illuminated target area with a video camera located at the distal end of the endoscope body; delivering therapeutic laser light from a distal end of an optical fiber extending distally from the distal end of the endoscope body toward the target site, the therapeutic laser light having at least one therapeutic laser light wavelength; receiving returned light at a distal end of the optical fiber; performing a spectroscopic measurement of the returned light to determine a measured light level in a detection spectral region that does not overlap with the visible light illumination spectrum and does not include the at least one therapeutic laser light wavelength; using a processor circuit to compare the measured light level to a threshold light level; determining, with the processor circuit, that the measured light level exceeds the threshold light level; generating, with the processor circuit, a flushing event data signal indicating that a flushing event has occurred at the distal end of the optical fiber in response to determining that the measured light level exceeds the threshold light level; A method comprising:

13. 13. The method of claim 12, further comprising the step of: using the processor circuit to cause an actuator to retract the optical fiber proximally relative to the endoscope body a specified distance in response to determining that the measured light level exceeds the threshold light level, the specified distance being sufficient to terminate the flushing event.

14. displaying the video image of the illuminated target area on a video display coupled to the processor circuit; suppressing, with the processor circuit, the video image in response to determining that the measured light level exceeds the threshold light level such that the video display does not display the video image when the flashing event occurs; The method of claim 12 further comprising:

15. delivering irrigant to the target site at a controllable irrigation rate using an irrigation regulator coupled to the endoscope; increasing the irrigation rate with the irrigation regulator in response to determining that the measured light level exceeds the threshold light level; The method of claim 12 further comprising:

16. an endoscope having an endoscope body; an illumination source disposed at a distal end of the endoscope body and configured to illuminate a target site with visible light illumination having a visible light illumination spectral range; a video camera disposed at the distal end of the endoscope body and configured to capture video images of the illuminated target area; a video display configured to display the video image of the illuminated target area; An optical fiber extending from the endoscope body, delivering therapeutic laser light from the distal end of the optical fiber toward the target site, the therapeutic laser light having at least one therapeutic laser light wavelength; receiving return light at the distal end of the optical fiber; an optical fiber configured to perform a spectrometer configured to spectroscopically measure the returned light; 1. A processor circuit, comprising: determining from the spectroscopic measurement of the returned light when a light level of the returned light at at least one flashing event wavelength rises above a threshold light level, the at least one flashing event wavelength being different from the at least one therapeutic laser light wavelength and outside the visible light illumination spectral range; generating a flushing event data signal in response to determining that the light level has risen above the threshold light level, indicating that a flushing event has occurred at the distal end of the optical fiber; a processor circuit configured to:

1. A laser tissue ablation system comprising:

17. 17. The laser tissue ablation system of claim 16, further comprising: an actuator controllable by the processor circuit, the actuator configured to automatically retract the optical fiber proximally relative to the endoscope body a specified distance in response to determining that the light level has risen above the threshold light level, the specified distance being sufficient to terminate the flushing event.

18. 17. The laser tissue ablation system of claim 16, wherein the processor circuitry is further configured to suppress the video image in response to determining that the light level has risen above the threshold light level such that the video display does not display the video image when the flashing event occurs.

19. 17. The laser tissue ablation system of claim 16, further comprising an irrigation regulator coupled to the endoscope and configured to supply irrigant to the target site at a controllable irrigation rate, the processor circuit further configured to increase the irrigation rate in response to determining that the light level has risen above the threshold light level.

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