Techniques and systems for collapsing gas passage in liquid medium

Abstract

Techniques and laser systems for modulating laser pulses are provided. The laser pulse may be modulated to cause a gas path formed when the laser pulse is emitted into the liquid medium to collapse within a specified distance. The instantaneous power of the laser pulse may be modulated in a phase opposite to the growth of bubbles forming the gas path.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 63 / 348,719, filed on June 3, 2022, the entire disclosure of which is incorporated herein by reference. Background Art

[0003] The introduction of lasers into the medical field and the development of fiber optic technology using lasers have opened up numerous applications in treatment, diagnosis, therapy and the like. Such applications range from invasive and non-invasive treatments to endoscopic surgery and image diagnosis. For example, in the treatment of urinary stones, stones need to be broken into smaller fragments. A technique called laser lithotripsy can be used for such a fragmentation process, wherein for small to medium-sized urinary stones, a rigid or flexible ureteroscope is placed through the urethra for illumination and imaging. At the same time, an optical fiber is inserted into the target position (e.g., the location where the stone exists in the bladder, ureter or kidney) through the working channel of the ureteroscope. Then, the laser is activated to break the stone into smaller fragments or powder. In another case, laser and fiber optic technology are used for ablation therapy. During ablation therapy, a laser is delivered to the tissue to evaporate the tissue or cause damage in the tissue. This ablation therapy can be used to treat various clinical conditions, such as benign prostatic hyperplasia (BPH) or cancer (such as bladder cancer).

[0004] Clinical applications have shown that the use of lasers in lithotripsy can cause accidental damage to surrounding tissues (such as the ureter). Therefore, there are risks in the use of lasers in lithotripsy and other surgeries. Summary of the invention

[0005] The present disclosure provides medical devices and techniques for enhancing the safety of laser beams used in clinical surgery. In particular, the present disclosure is intended to enhance the safety of laser beams used in liquid environments. Many therapeutic surgeries are performed in liquid environments. Liquid environments tend to absorb a large portion of laser energy. For example, liquid media can absorb and attenuate laser energy, leaving less energy available for the desired surgical effect on the target. In addition, although the energy absorbed by the liquid medium can protect surrounding tissue by limiting the range of energy transfer, it can also heat the surrounding tissue, leading to unwanted side effects or potential safety issues. The present disclosure provides for controlling the presence or absence of liquid (e.g., based on modulated vapor tunneling, which will be described in detail below) to control the range of the laser beam.

[0006] Additionally, the need to flush these areas with cooling fluids may increase when lasers are used. These safety issues may become more complex based on the type of laser used in the procedure. For example, thulium fiber laser (TFL) is a laser modality employed in lithotripsy procedures. Although the absorption rate of laser energy emitted by TFL in liquid media is higher (e.g., four (4) times higher) than other laser media used in lithotripsy (e.g., holmium), injuries caused by TLF energy emission have been observed clinically. As a specific example, the expected average travel distance of light emitted by a thulium laser in water is 0.1 millimeters (mm), while the expected average propagation distance of light emitted by a holmium laser in water is 0.4 mm.

[0007] This is in part because lasers such as TFL can deliver longer pulses relative to some other laser modalities (e.g., due to peak power limitations, etc.), which can result in energy delivery to relatively large distances. More specifically, because TFL lasers have longer pulses relative to other modalities, more elongated vapor tunnels are formed in the liquid environment, resulting in a larger energy delivery range. This effect is independent of wavelength absorption in the liquid medium due to the creation of "vapor tunnels." During laser activation, the interaction between the laser energy and the liquid medium forms a gas pathway (or vapor tunnel) from a bubble or chain of bubbles in the liquid medium. The gas pathway has an absorption coefficient that is less than that of the liquid medium, thereby facilitating more laser energy to be delivered from the laser fiber tip to the target. In addition, the longer pulses of TFL create a more extensive thermal damage area (e.g., due to the relatively long exposure time of the tissue compared to the thermal relaxation constant of the tissue). It should be understood that shorter pulses will generally create more localized damage, with a more localized heat dissipation area, and therefore less thermal damage.

[0008] Thus, performing lithotripsy procedures using a TFL (or any laser that generates very long pulses) creates an increased potential safety risk. Several factors may further increase this safety risk. For example, the safety risk may increase when operating near sensitive areas (e.g., ureters) or operating in situations where visibility is limited (e.g., such as during lithotripsy due to turbid media created during lithotripsy). As another example, the safety risk may increase when working at high repetition rates or when the target is movable (e.g., such as where stones are dislodged due to backwashing, flushing, or other factors).

[0009] The present disclosure provides a laser system in which laser pulses are modulated so that the bubbles created by the laser pulses are intentionally collapsed to shorten the gas path, thereby reducing the reach (or propagation range) of the laser energy from the optical fiber tip. In other words, the present disclosure provides an apparatus and method for modulating laser pulses to avoid resonantly generated gas paths (or bubbles) outside of the intended target.

[0010] In a particular embodiment, the laser pulses are modulated with a phase opposite to that of the gas bubble. As another specific embodiment, a distance from the tip of the optical fiber to the target is determined (e.g., estimated, measured, etc.), and the laser pulses are modulated to achieve growth of the gas pathway to the determined distance. As another example, the laser pulses are modulated so that the gas pathway is greater than or equal to the determined distance minus a threshold distance, and less than or equal to the determined distance plus a threshold distance. The modulation of the laser pulses can be repeated cyclically to continue the treatment while maintaining (e.g., growing or collapsing) the gas pathway so that the gas pathway is within a threshold of the desired distance.

[0011] In some embodiments, the power of the laser pulses can be reduced based on a change in the distance between the tip of the optical fiber and the target being greater than or equal to a threshold level. As another embodiment, the power of the laser pulses can be reduced based on a change in the distance between the tip of the optical fiber and the target being greater than or equal to a threshold level over a specified time period. For example, a sudden increase in the distance between the tip of the optical fiber and the target can indicate that the actual target (e.g., a stone, etc.) has moved and the optical fiber is now pointing directly at the tissue behind the location of the stone. In another example, a system capable of distinguishing between stones and soft tissue can collapse the steam tunnel when tissue is detected.

[0012] These and other embodiments of the present disclosure will become apparent from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Non-limiting embodiments of the present disclosure are described by way of example with reference to the accompanying drawings, which are schematic and are not intended to be drawn to scale. It should be understood that the various figures included in the present disclosure may omit some components, show portions of some components, and / or render some components as transparent to facilitate illustration and description of components that may appear hidden. For clarity, not every component is labeled in every figure, nor is every component of every embodiment shown, where an illustration is not necessary to allow a person of ordinary skill in the art to understand the present disclosure. In the drawings:

[0014] Figure 1 A graph depicting a gas path according to at least one embodiment is shown.

[0015] Figure 2 Another graph depicting a gas path is shown in accordance with at least one embodiment.

[0016] Figure 3 A system in accordance with at least one embodiment is shown.

[0017] Figure 4 A treatment environment is shown in accordance with at least one embodiment.

[0018] Figure 5 A method according to at least one embodiment is shown.

[0019] Figure 6 Another method in accordance with at least one embodiment is shown.

[0020] Figure 7 Another method in accordance with at least one embodiment is shown.

[0021] Figure 8 A block diagram of a computing environment is shown in accordance with at least one embodiment. DETAILED DESCRIPTION

[0022] The foregoing generally summarizes some features and technical advantages of the present disclosure, so as to better understand the following detailed description of the present disclosure. It should be understood by those skilled in the art that the disclosed embodiments can be easily used as the basis for modifying or designing other structures for achieving the same purpose of the present disclosure. For example, without departing from the scope of the present disclosure, the components and features disclosed herein can be selectively combined. When considered in conjunction with the accompanying drawings, the novel features of the present disclosure (including both its organization and operation method) and further purposes and advantages can be better understood from the following description. However, it should be clearly understood that each figure provided is only for the purpose of illustration and description and is not intended to be a definition of claim limitations. In addition, although various embodiments can be described for laser lithotripsy or laser ablation treatment, reference to these conditions should not be interpreted as limiting the possible applications of the disclosed aspects. For example, the disclosed aspects can be utilized to treat clinical conditions, such as cancer (e.g., liver cancer, lung cancer, etc.) or heart disease (e.g., by ablating and / or coagulating a portion of tissue in the heart).

[0023] It should be understood that control of the gas path is complicated by the complexity of the dynamics and harmonics of bubbles formed in liquid media and the differences between the energy emissions of different types of lasers. For this reason, laser pulses and bubble formation are discussed before describing the techniques for modulating laser pulses to intentionally collapse bubbles.

[0024] In some embodiments of the present disclosure, lasers with low peak power and long pulses, such as TFL, can be utilized so that the overall size and stability of the generated bubble cascade is much longer (along the fiber axis from the laser fiber tip to the target) than a single bubble of a typical short pulse laser. Thus, surprisingly, although thulium (Tm) photons have much stronger absorption in water than holmium (Ho), when comparing short pulse Ho and long pulse Tm, the latter travels farther while passing through the longer bubble chain generated by the TFL. In addition, the longer pulse duration better utilizes the bubble cascade because the pulse persists while the bubble reaches the target. While it has been observed that the TFL pulse is split into several sub-pulses due to the collapse of multiple bubbles, which generally results in a large variation in energy delivery during the pulse duration, the Ho laser energy can produce similar overall energy delivery.

[0025] As mentioned above, the bubble has its own dynamics, and once initiated, it is no longer related to the characteristics of the laser pulse in many respects. The initial bubble formed by firing the laser first grows to a maximum size (depending on the initial peak power of the pulse), and then collapses. The typical bubble duration for a Ho laser is about 200 to 300 microseconds (μs). Laser pulses that are longer than the bubble's lifetime create a series of several bubbles that are fired from the laser fiber tip toward the target.

[0026] Infrared lasers, such as Ho lasers (having a wavelength of about 2100 nanometers (nm)) and Tm lasers (having a wavelength of about 1940 nm to 2010 nm) are strongly absorbed in liquid environments. For example, a photon with a wavelength of 1940 nm has a wavelength of 110 centimeters (cm). -1 The absorption coefficient of the photon with a wavelength of 2100nm is 25cm -1absorption coefficient. Typically, in a liquid environment, many photons generated by a Ho laser are absorbed before the laser pulse travels a distance of 0.5 mm from where it leaves the fiber, while photons generated by a Tm laser are absorbed before the laser pulse travels a distance of 0.1 mm from where it leaves the fiber. Similarly, solid-state Ho lasers are characterized by high peak power and relatively short pulses, while Tm fiber lasers (TFLs) are characterized by lower peak power. Therefore, a TFL requires a longer time to generate the same amount of energy than a solid-state Ho laser. For example, a TFL will generate 0.5 joules of energy in a pulse duration of about 1 millisecond (ms), while a solid-state Ho laser will require approximately 0.2 ms to generate the same amount of energy. As will be discussed further below, the life cycle of a single bubble has been observed to last approximately 0.2 ms to 0.3 ms. In addition, it has been observed that once initiated, the bubble has its own dynamic characteristics that are in many ways independent of the laser pulse (except for the initial characteristics of the pulse within a very short time frame of tens of microseconds). Based on the above, a short solid-state Ho laser pulse can end the bubble before it reaches its maximum size, while a longer TFL pulse will last 3 to 4 times longer than the bubble lifetime.

[0027] As described above, laser pulses that are longer than the lifetime of a single bubble result in the creation of a cascade of multiple bubbles. The cascade of multiple bubbles can create a gas pathway to the target. However, this bubble cascade is characterized by a series of independent bubbles that expand and collapse at different times and at different locations along the pathway. Therefore, the effective length of the gas pathway varies with time.

[0028] Figure 1 An exemplary graph 100 of pulses of a Ho laser and a Tm laser according to one or more embodiments described herein is shown. In the illustrated embodiment, the Ho and Tm lasers have equal energy of 0.2 Joules (J). Graph 100 shows the relationship between a typical high peak power Ho laser short pulse and a low peak power quasi-continuous Tm long pulse. Graph 100 includes bubble size (in mm) on the positive y-axis 102 (where the potential target location is at line 108), pulse power (in Watts (W)) on the negative y-axis 104, and time (in μs) on the x-axis 106. For the high peak power Ho laser short pulse, area 110 corresponds to the pulse power, curve 112 corresponds to the bubble created, and line 114 corresponds to the effective distance the laser pulse travels through the liquid medium. For the low peak power quasi-continuous Tm long pulse, area 116 corresponds to the pulse power, curve 118 corresponds to the bubble created, and line 120 corresponds to the effective distance the laser pulse travels through the liquid medium.

[0029] In both cases, the bubble is created and begins to expand after a short delay of about tens of microseconds (μs) after the laser pulse is initiated. In both cases, the life cycle of the bubble, once created, appears to have its own internal dynamics that are related not only to the laser pulse, but also to the internal vapor pressure generated at the bubble nucleation site, which in turn depends on absorption, instantaneous peak power, laser beam quality, and / or the presence and amount of gas pockets inside the liquid.

[0030] It takes time for the bubble to expand. In the case of Ho pulses, the bubble reaches its maximum size well after the highest power peak of the laser, and in the case of Tm lasers the bubble reaches its maximum size during the laser pulse. Figure 1 10 also shows that for an exemplary target distance 112 (positioned at a distance of about 3 mm), the effective distance that a Tm laser pulse can travel through the liquid medium (e.g., line 120) is much longer than the effective distance that a Ho laser pulse can travel through the liquid medium (e.g., line 114). Several embodiments described herein utilize the independent dynamics of bubbles to intentionally collapse the bubbles to reduce or limit the distance that the laser pulses travel through the liquid medium. In particular, the present disclosure provides for modulating the laser pulse power in an opposite phase to the bubbles to intentionally collapse the bubbles (or intentionally collapse the tunnel created by a chain of bubbles) to avoid resonant generation of bubbles beyond the intended target.

[0031] Figure 2 An exemplary graph 200 of laser pulse power modulation 204 as a function of bubble size 202 is shown in accordance with one or more embodiments described herein. In various embodiments, graph 200 includes an exemplary pulse power modulation scheme. The pulse modulation scheme may include one or more settings, modes, parameters, characteristics, features, etc. of the pulse, environment (e.g., liquid medium, distance), and / or various components (see, e.g., laser system 300) for implementing the pulse. The pulse power modulation 204 is illustrated by the sinusoidal pattern shown in the slanted shaded area. In this case, the power is modulated from a high level of 500W to a low level of 300W. According to this aspect of the disclosure, the laser power on the long pulse is modulated in a direction opposite to the bubble dynamics described above, such that when the bubble expands, the laser is modulated downward, and when the bubble collapses, the laser is modulated upward. Embodiments are not limited thereto.

[0032] Figure 3300 according to one or more non-limiting examples of the present disclosure is shown. The laser system 300 includes a console 302 and a fiber optic cable 304. In general, the laser system 300 is arranged to generate laser energy emissions and modulate the laser emissions to control the size of bubbles when the laser energy is emitted in a liquid medium. For example, the laser system 300 can be implemented to modulate the laser energy pulses so that the bubbles created by the laser pulses are intentionally collapsed to shorten the gas path formed by the bubbles, with the aim of reducing the reach (or propagation range) of the laser energy emitted from the tip of the optical fiber coupled to the laser system 300.

[0033] Laser system 300 includes console 302 and fiber optic cable 304 coupled to the console. It should be noted that although console 302 and components of console 302 are depicted as being arranged in a single housing, some examples may provide multiple housings. Console 302 includes laser source 306, optical components 308, optical coupler 310, and controller 312. Console 302 may also optionally include display 314 and / or input and / or output (I / O) device 316.

[0034] Although not shown in this figure, it should be understood that the laser system 300 can be included in, integrated into, or connected to a therapeutic laser system, such as a laser ablation system arranged to perform one or more laser therapeutic procedures (e.g., lithotripsy, ablation, etc.). In particular, the laser system 300 can be implemented to enhance or increase the safety of laser therapeutic procedures.

[0035] The laser source 306 may include a laser (e.g., TFL, Ho laser, etc.) arranged to generate a treatment beam. The optical component 308 may include any of a variety of optical components (e.g., polarizers, beam splitters, beam combiners, photodetectors, filters, wavelength division multiplexers, collimators, circulators) arranged to couple light emitted from the laser source 306 with an optical coupler 310 and ultimately with the fiber optic cable 304. The optical coupler 310 may be arranged to provide optical coupling between the proximal end of the fiber optic cable 304 and the console 302, so that the light emitted from the laser source 306 can be transmitted through the fiber optic cable 304 and emitted by the distal end of the fiber optic cable 304.

[0036] The controller 312 may include circuitry such as an application specific integrated circuit (ASIC). As another example, the controller 312 may include a processor and a memory storing instructions executable by the processor that, when executed, cause the laser system 300 to perform the operations described herein. For example, the controller 312 may be arranged to cause the laser system 300 (and in particular the laser source 306) to modulate pulses emitted by the laser source 306 so that bubbles and gas pathways generated when laser energy is emitted from the distal end of the fiber optic cable 304 collapse within a specified distance from the distal end of the fiber optic cable 304.

[0037] Additionally, in some embodiments, the optical component 308 may include an optical receiver arranged to measure the amount of light reflected from the laser system 300 (e.g., through the input face of the fiber optic cable 304, through the output face of the fiber optic cable 304, through (see Figure 4 ) etc.). As will be explained in more detail herein, the laser system 300 can measure the distance between the distal end of the fiber optic cable 304 and the target and use the measured distance to control the gas path (see Figure 4 That is, the controller 312 may send a control signal to the laser source 306 to cause the laser source 306 to modulate the instantaneous power of the generated laser pulses based on the measured distance (e.g., causing the gas passage to collapse) within a threshold distance of the measured distance.

[0038] The display 314 may include any of a variety of displays (e.g., an LCD display, LEDs, etc.) arranged to provide visual indications (e.g., graphics, graphical user interfaces, graphical elements, light sequences, etc.) to convey information to a user of the laser system 300. The I / O device 316 may include any of a variety of devices (e.g., a mouse, a keyboard, a joystick, buttons, pedals, speakers, etc.) arranged to receive input from a user or provide output to a user. Using the display 314 and the I / O device 316, a user may interact with the laser system 300 (e.g., provide input to the laser system 300 or receive output from the laser system 300) to, for example, provide an indication of an expected distance that a bubble will collapse or an indication of a desired distance that a bubble will collapse.

[0039] Figure 4A treatment environment 400 is shown. As contemplated herein, the treatment environment 400 will be a liquid medium, such as, for example, a liquid medium that may be encountered in a lithotripsy procedure. The distal end 402 of the fiber optic cable 304 is introduced into the treatment environment 400, such as, for example, via a working channel or a ureteroscope (not shown). A laser pulse 404 is emitted from the distal end 402 into the treatment environment 400 toward a target 406. For example, a clinician can "aim" the distal end 402 at the target 406 (via positioning the distal end 402 or a ureteroscope, etc.). The clinician can then activate a laser source (e.g., laser source 306, etc.) so that a laser pulse 404 will be generated and emitted into the treatment environment 400. As outlined above, the laser pulse 404 will generate bubbles in the treatment environment 400, forming a gas passage 408. The present disclosure provides for modulating the instantaneous power of the laser pulse 404 so that the gas passage 408 collapses at a specified distance. In some examples, the instantaneous power of laser pulse 404 is modulated in phase opposite to the growth of a bubble (not shown) that forms gas passage 408. In some embodiments, the instantaneous power of laser pulse 404 is modulated such that gas passage 408 collapses between 1 and 1.3 times the distance (e.g., distance 410) between distal end 402 and target 406, which is depicted as threshold distance 412.

[0040] Figure 5 A method 500 for modulating laser pulses to control the size of a gas passage created by a bubble when the laser pulses are emitted into a liquid medium is shown. The method 500 may represent some or all of the operations that may be performed by one or more components, devices, or systems described herein, such as one or more portions of the laser system 300. In addition, the method 500 may be implemented by a medical device arranged to emit laser energy into a liquid medium (e.g., the treatment environment 400) as part of using the medical device as a therapeutic procedure (e.g., lithotripsy). Although the laser system 300 and the treatment environment 400 are used in describing the method 500, the embodiments are not limited thereto, and the method 500 may be implemented by a laser system having a different arrangement than the laser system 300 or including different components than shown or described with respect to the laser system 300.

[0041] As depicted, method 500 may begin at block 502. At block 502, “Emit multiple laser energy pulses from a laser source,” a number of laser energy pulses are emitted from a laser source. For example, laser source 306 may generate laser energy pulses and cause the laser energy pulses to be emitted from fiber optic cable 304 (e.g., as laser pulses 404, etc.).

[0042] Continuing with block 504, “Modulating the instantaneous power of the plurality of pulses so that when the laser energy is emitted from the fiber optic cable into the liquid medium, the bubbles formed by the laser energy pulses collapse within a threshold of a specified distance,” the instantaneous power of the laser pulses generated by the laser source (e.g., at block 502) may be modulated to cause the bubbles formed when the laser pulses are emitted into the liquid medium to collapse within a specified distance. For example, the controller 312 may send a signal (e.g., a control signal, an information element, etc.) to the laser source 306 to cause the laser source 306 to modulate the instantaneous power of the generated laser pulses (e.g., the laser pulses 404) to cause the gas passage 408 to collapse within the threshold distance 412.

[0043] It should be understood that, as used herein, the instantaneous power of a laser pulse generated by a laser source can be modulated upward (e.g., to increase power) or downward (e.g., to decrease power) to increase or decrease the length of a bubble. Furthermore, it should be understood that the amount of modulation of the instantaneous power (e.g., upward or downward) can be based on a variety of methods. For example, the controller 312 can send a signal to the laser source 306 to cause the laser source 306 to modulate the instantaneous power of a laser pulse (e.g., laser pulse 404) based on a lookup table that includes an indication of a relationship of bubble length to pulse on-time (e.g., as a function of peak power, wavelength, etc.). As another example, the controller 312 can send a signal to the laser source 306 to cause the laser source 306 to modulate the instantaneous power of a laser pulse (e.g., laser pulse 404) based on a simulation or model that is configured to predict or infer bubble length based on laser parameters (e.g., peak power, wavelength, on-time, etc.). As another example, the controller 312 can send a signal to the laser source 306 to cause the laser source 306 to modulate the instantaneous power of a laser pulse (eg, the laser pulse 404 ) based on directly measuring the length of the bubble.

[0044] For example, the controller 312 can send a signal to the laser source 306 to cause the laser source 306 to turn on and off pulses at regular intervals. As a specific example, generating a 100 microsecond (μs) laser pulse and pausing to generate a 50 second (μs) laser pulse, repeated until a specified amount of energy is generated by the laser source, can limit the range of the laser energy to approximately 2.5 millimeters (mm). For any given combination of pulse energy and distance threshold, the present disclosure can generate a predetermined modulation sequence that can be applied by the controller 312.

[0045] Figure 6A method 600 is shown for modulating laser pulses to control the size of gas pathways created by bubbles when the laser pulses are emitted into a liquid medium. Method 600, like method 500, can represent some or all of the operations that can be performed by one or more components, devices, or systems described herein, such as one or more portions of laser system 300. In addition, method 600 can be implemented by a medical device arranged to emit laser energy into a liquid medium (e.g., treatment environment 400) as part of using the medical device as a therapeutic procedure (e.g., lithotripsy). Although laser system 300 and treatment environment 400 are used in describing method 600, embodiments are not limited thereto, and method 600 can be implemented by a laser system having a different arrangement than laser system 300 or including different components than shown or described with respect to laser system 300.

[0046] As depicted, method 600 may begin at block 602. At block 602, “RECEIVE AN INDICATION OF A DISTANCE BETWEEN A FAR END OF A FIBER OPTIC CABLE AND A TARGET,” an indication of a distance between a far end of a fiber optic cable and a target is received. For example, controller 312 may receive an indication (e.g., from a measurement subsystem, from one of optical components 308, etc.) of distance 410, such as Figure 4 Depicted, distance 410 is the distance between distal end 402 and target 406 .

[0047] Continuing to decision box 604, "Did the distance change more than allowed?", it is determined whether the distance has changed by more than the allowed amount. For example, the controller 312 can determine whether the distance 410 (e.g., received at box 602) has changed by more than the allowed (or threshold) amount. In a specific example, the controller 312 can determine whether the distance 410 has changed by more than a threshold amount (change threshold) within a set time period. For some examples, the threshold for the distance change allowed can be 10%, 20%, 25%, etc. For some examples, the threshold for the allowed change can be 10% in one second, 20% in one second, or 25% in one second. For some embodiments, at decision box 604, the controller 312 can also determine whether the distal end of the fiber optic cable 304 is directed toward the stone or the tissue, and can continue to box 606 based on the determination that the distal end of the fiber optic cable is directed toward the stone, or continue to box 614 based on the determination that the distal end of the fiber optic cable is directed toward the tissue and end the treatment (or in other words, collapse the steam tunnel).

[0048] From decision block 604, method 600 may continue to block 606, or may jump to completion block 614 and end. Specifically, method 600 may continue from decision block 604 to block 606 based on a determination at decision block 604 that distance 410 has not changed by more than a threshold amount, while method 600 may jump to completion block 614 and end based on a determination at decision block 604 that distance 410 has changed by more than a threshold amount. At completion block 614, “END TREATMENT,” the treatment regimen may be paused or terminated, and controller 312 may send a control signal to laser source 306 to cause 306 to pause or terminate generation of laser pulses.

[0049] At block 606, “GENERATING PLURAL LASER ENERGY PULSE AT LASER SOURCE”, the laser source may generate a number of laser energy pulses. For example, laser pulse 404 may be generated at laser source 306. Continuing with block 608, “ELECTRICALLY EMISSION LASER ENERGY FROM FIBER OPTIC CABLE”, the generated laser energy pulses may be emitted from the fiber optic cable. For example, laser pulse 404 may be emitted from distal end 402 of fiber optic cable 304.

[0050] Continuing with block 610, “Modulating the instantaneous power of the plurality of laser energy pulses such that when the laser energy is emitted from the fiber optic cable into the liquid medium, the gas passage formed by the laser energy pulses collapses within a distance threshold,” the instantaneous power of the laser pulses is modulated such that the gas passage formed when the laser pulses are transmitted into the liquid medium collapses within a distance threshold. For example, the controller 312 may send a signal (e.g., a control signal, an information element, etc.) to the laser source 306 to cause the laser source 306 to modulate the instantaneous power of the generated laser pulses (e.g., the laser pulses 404) to cause the gas passage 408 to collapse within a threshold distance 412 (e.g., a collapse threshold).

[0051] Continuing to decision block 612, "Continue treatment?", a determination may be made as to whether to continue treatment. For example, the controller 312 may determine whether to continue the treatment regimen based on received input (e.g., foot pedal actuation, etc.). As another example, the controller 312 may determine whether to continue the treatment regimen based on parameters of the protocol (e.g., total time to emit laser pulses, overall power of generated laser pulses, etc.). The method 600 may return to block 602 from decision block 612, or may continue to block 614. The method 600 may return to block 602 from decision block 612 based on a determination at decision block 612 that the treatment regimen will continue, while the method 600 may continue to block 614 from decision block 612 based on a determination at decision block 612 that the treatment regimen will not continue. In this manner, the method 600 provides for modulation of the laser pulses to repeat cyclically, thereby continuing the treatment regimen while maintaining (e.g., growing or collapsing) the gas passage 408 so that the gas passage 408 is within a threshold of the distance 410, even if the distance 410 changes during the treatment regimen.

[0052] Figure 7 A method 700 is shown for modulating laser pulses to control the size of a gas passage created by a bubble when the laser pulses are emitted into a liquid medium. Method 700, like methods 500 and 600, can represent some or all of the operations that can be performed by one or more components, devices, or systems described herein, such as a portion or portions of laser system 300. In addition, method 700 can be implemented by a medical device arranged to emit laser energy into a liquid medium (e.g., treatment environment 400) as part of using the medical device as a therapeutic procedure (e.g., lithotripsy). Although laser system 300 and treatment environment 400 are used in describing method 700, embodiments are not limited thereto, and method 700 can be implemented by a laser system having a different arrangement than laser system 300 or including different components than shown or described with respect to laser system 300.

[0053] As depicted, method 700 may begin at block 702. At block 702, “RECEIVE AN INDICATION OF A REQUIRED DISTANCE AND A PROVISIONED LASER ENERGY,” an indication of a desired distance (e.g., a desired distance for laser propagation, a desired distance between the distal end of the fiber tip and a target, a desired distance for a steam tunnel, etc.) and a desired laser energy source is received. For example, controller 312 may receive an indication (e.g., from a user interface, etc.) of a desired length of gas passage 408 (e.g., distance 410, etc.) and an indication of a desired or prescribed energy of laser pulse 404. Continuing at block 704, “GENERATING A MULTIPLE LASER ENERGY PULSE AT LASER SOURCE,” a laser source may generate a number of laser energy pulses. For example, laser pulse 404 may be generated at laser source 306. Continuing at block 706, “EMISSING LASER ENERGY FROM FIBER OPTIC CABLE,” the generated laser energy pulses may be emitted from the fiber optic cable. For example, laser pulse 404 may be emitted from distal end 402 of fiber optic cable 304.

[0054] Continuing to decision block 708, "Will the prescribed laser energy cause the gas passage to have a length greater than the desired distance?" a determination is made as to whether the prescribed laser energy source (e.g., a pulse generated as in block 704, etc.) will cause the gas passage 408 to be greater than the desired distance. In one specific example, the controller 312 may determine whether the energy of the pulse 404 will cause the gas passage 408 to grow to a distance 410 greater than the desired distance. From decision block 708, the method 700 may continue to block 710, or may jump to block 714. Specifically, method 700 can continue from decision box 708 to box 710 based on the determination at decision box 708 that the laser energy will cause the distance 410 associated with the gas passage 408 formed by the pulse generated at box 704 and emitted at box 706 to grow longer than the desired distance, while method 700 can skip to box 714 based on the determination at decision box 708 that the laser energy will not cause the distance 410 associated with the gas passage 408 formed by the pulse generated at box 704 and emitted at box 706 to grow longer than the desired distance.

[0055] At block 710, “Downward Modulation of Instantaneous Power of Laser Energy Pulses Generated by Laser Source,” the laser energy of the pulses generated by the laser light source may be downward modulated. For example, the instantaneous power of the laser energy pulse may be modulated to a specified percentage (e.g., 10%, 20%, 25%, etc.) such that the gas passage 408 collapses. As a specific example, the controller 312 may determine whether to downwardly modulate the instantaneous power of the laser energy pulse by a specified percentage (e.g., 10%, etc.) after a time corresponding to an on-time of a prescribed energy pulse associated with a gas passage having a length equal to a desired distance.

[0056] Continuing with block 712, “After a delay, upwardly modulate the instantaneous power of the laser energy pulse generated by the laser source,” the laser energy of the pulse generated by the laser source may be upwardly modulated. For example, the instantaneous power of the laser energy pulse may be modulated back to a prescribed power so that the gas passage will grow to a desired length again. For some examples, at block 712, the controller 312 may modulate the instantaneous power of the laser pulse back to a prescribed power after a delay (e.g., 5 microseconds, 10 microseconds, 20 microseconds, etc.).

[0057] It should be understood that for long pulses, the procedure outlined in method 700 may be repeated several times. For example, method 700 may include decision box 714 "Continue treatment?", where it may be determined whether to continue treatment. For example, controller 312 may determine whether to continue the treatment regimen based on treatment parameters (e.g., total energy delivered to the target, total on time, etc.). Method 700 may return to box 702 from decision box 714, or may continue to box 716 and end. That is, method 700 may return to box 702 from decision box 714 based on a determination at decision box 714 that the treatment regimen will continue, and method 700 may continue to box 716 from decision box 714 based on a determination at decision box 714 that the treatment regimen will not continue.

[0058] Figure 8 8 is a block diagram of a computing environment 800 including a computer system 802 for implementing embodiments consistent with the present disclosure. In some embodiments, the computing environment 800 or a portion thereof (e.g., the computer system 802) may include or be included in a laser system (e.g., the controller 312 of the laser system 300 may be embodied as a portion of the computing environment 800). Thus, in various embodiments, the computer system 802 may determine a distance and control modulation of the laser pulse power based on the determined distance so that a gas channel formed when the laser pulse is emitted into the liquid medium collapses within a threshold value of the distance.

[0059] The computer system 802 may include a central processing unit ("CPU" or "processor") 804. The processor 804 may include at least one data processor for executing instructions and / or program components to perform user or system generated processes. The user may include a person, a person using a device such as included in the present disclosure, or another device. The processor 804 may include a special processing unit such as an integrated system (bus) controller, a memory management control unit, a floating point unit, a graphics processing unit, a neural processing unit, a digital signal processing unit, etc. The processor 804 may be arranged to communicate with an input device 814 and an output device 816 via an I / O interface 812. The I / O interface 812 may employ communication protocols / methods such as, but not limited to, audio, analog, digital, stereo, IEEE-1394, serial bus, universal serial bus (USB), infrared, PS / 2, BNC, coaxial, component, composite, digital video interface (DVI), high-definition multimedia interface (HDMI), radio frequency (RF) antenna, S-Video, video graphics array (VGA), IEEE 802.n / b / g / n / x, Bluetooth, cellular (e.g., code division multiple access (CDMA), high-speed packet access (HSPA+), global system for mobile communications (GSM), long term evolution (LTE), WiMAX, or the like), etc.

[0060] Using the I / O interface 812, the computer system 802 can communicate with input devices 814 and output devices 816. In some embodiments, the processor 804 can be configured to communicate with a communication network 820 via a network interface 810. In various embodiments, the communication network 820 can be utilized to communicate with a remote memory storage device 806, such as for accessing a lookup table, performing updates, or utilizing external resources. The network interface 810 can communicate with the communication network 820. The network interface 810 can employ a connection protocol including, but not limited to, direct connection, Ethernet (e.g., twisted pair 10 / 100 / 1000Base T), Transmission Control Protocol / Internet Protocol (TCP / IP), Token Ring, IEEE 802.11a / b / g / n / x, etc.

[0061] The communication network 820 may be implemented as one of different types of networks, such as an intranet or local area network (LAN), a closed area network (CAN), etc. The communication network 820 may be a dedicated network or a shared network, which represents an association of different types of networks that communicate with each other using various protocols (e.g., Hypertext Transfer Protocol (HTTP), CAN protocol, Transmission Control Protocol / Internet Protocol (TCP / IP), Wireless Application Protocol (WAP), etc.). In addition, the communication network 820 may include various network devices, including routers, bridges, servers, computing devices, storage devices, etc. In some embodiments, the processor 804 may be configured to communicate with the memory storage device 806 via a storage interface 808. The storage interface 808 may be connected to the memory storage device 806, including but not limited to a memory drive, a removable disk drive, etc., using connection protocols such as Serial Advanced Technology Attachment (SATA), Integrated Drive Electronics (IDE), IEEE-1394, Universal Serial Bus (USB), Fiber Channel, Small Computer System Interface (SCSI), etc. The memory drive may also include a magnetic drum, a magnetic disk drive, a magneto-optical drive, an optical disk drive, a redundant array of independent disks (RAID), a solid-state storage device, a solid-state drive, etc.

[0062] In addition, the memory storage device 806 may include one or more computer-readable storage media used in the implementation of the embodiments consistent with the present disclosure. Generally, a computer-readable storage medium refers to any type of physical memory in which information or data readable by a processor can be stored. Therefore, a computer-readable storage medium can store instructions for one or more processors to execute, including instructions for causing one or more processors to execute steps or stages consistent with the embodiments described herein. The term "computer-readable medium" should be understood to include tangible items and does not include carrier waves and transient signals, i.e., non-transient signals. Examples include random access memory (RAM), read-only memory (ROM), volatile memory, non-volatile memory, hard disk drive, compact disk (CD) ROM, digital video disk (DVD), flash drive, disk, and any other known physical storage medium.

[0063] The memory storage device 806 may store a collection of program or database components, including, but not limited to, an operating system 822, application instructions 824, and user interface elements 826. In various embodiments, the operating system 822 may facilitate resource management and operation of the computer system 802. Examples of operating systems include, but are not limited to, OS UNIX-like system distributions (for example, BERKELEY SOFTWARE (BSD), OPENBSD, etc.), Distribution (for example, wait), ( 10, etc.), GOOGLETM ANDROIDTM, OS, etc.

[0064] The application instructions 824 may include instructions that, when executed by the processor 804, cause the processor 804 to perform one or more techniques, steps, procedures, and / or methods described herein to control the length of a gas passage (e.g., the gas passage 408). For example, when executed by the processor 804, the application instructions 824 may cause the processor 804 to perform the method 500 and / or the method 600.

[0065] User interface elements 826 may facilitate the display, execution, interaction, manipulation, or operation of program components through text or graphical tools. For example, a user interface may provide computer interaction interface elements such as cursors, icons, check boxes, menus, scroll bars, windows, widgets, etc. on a display system operably connected to computer system 802. User interface elements 826 may be employed by application instructions 824 and / or operating system 822 to provide, for example, a user interface with which a user may interact with computer system 802. In some embodiments, user interface elements 826 may be integrated with a display (e.g., display 314).

[0066] Regarding the use of substantially any plural and / or singular terms herein, those skilled in the art can translate from the plural to the singular and / or from the singular to the plural as the context and / or application requires. For clarity and not limitation, various singular and / or plural arrangements are expressly set forth herein.

[0067] Those skilled in the art will understand that, in general, the terms used herein are generally intended to be used as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to", the term "having" should be interpreted as "having at least", the term "including" should be interpreted as "including but not limited to", etc.). Those skilled in the art will further understand that if a specific number of an introduced claim recitation is intended. For example, to aid understanding, the detailed description may contain the use of introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be interpreted as implying that the introduction of a claim recitation by the indefinite article "a" or "an" limits any particular claim containing such introduced claim recitation to a disclosure containing only one such recitation, even if the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" and "an" (e.g., "a" and / or "an" should generally be interpreted as "at least one" or "one or more"); the same is true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim is explicitly recited, those skilled in the art will recognize that such recitation should generally be interpreted to mean at least the recited number (e.g., a simple recitation of "two recitations" without other modifiers generally means at least two recitations, or two or more recitations).

[0068] In view of the present disclosure, all devices and / or methods disclosed and claimed herein can be made and executed without undue experimentation. Although the devices and methods of the present disclosure have been described in terms of preferred embodiments, it will be apparent to those skilled in the art that changes may be applied to the devices and / or methods and the steps or sequence of steps of the methods described herein without departing from the concept, spirit and scope of the present disclosure. All such similar substitutions and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the present disclosure as defined by the appended claims.

Claims

1. A method, comprising: generating a plurality of laser energy pulses at a laser source to be emitted from a fiber optic cable disposed in a liquid environment; as well as The instantaneous power of the plurality of laser energy pulses is modulated to cause a gas passage in the liquid environment to collapse within a threshold of a specified distance.

2. The method according to claim 1, wherein: The plurality of laser pulses form bubbles in the liquid medium, and wherein the gas passages are formed by the bubbles.

3. The method according to claim 2, wherein: The instantaneous power is modulated in phase opposite to the growth of the bubble.

4. The method according to claim 3, wherein: The instantaneous power is modulated to a lower level at the time when the bubble is estimated to reach a maximum size.

5. The method according to claim 1, comprising: receiving an indication of a distance between an end of the fiber optic cable and a target, wherein the distance is the specified distance; as well as The instantaneous power of the plurality of laser energy pulses is modulated based on the distance, an initial power of the plurality of laser energy pulses, and an absorption coefficient of the liquid at a wavelength of the laser source.

6. The method according to claim 1, comprising: receiving an indication of an updated distance between an end of the fiber optic cable and a target; as well as The instantaneous power of the plurality of laser energy pulses is modulated to cause the gas passage in the liquid environment to collapse within a threshold of the updated distance.

7. The method according to claim 6, comprising: determining whether an absolute difference between the distance and the updated distance is greater than or equal to a second threshold; as well as Based on a determination that the absolute difference is greater than or equal to the second threshold, generation of the plurality of laser energy pulses is terminated.

8. The method according to claim 7, wherein: The instantaneous power is modulated in phase opposite to the growth of the bubble.

9. The method according to claim 8, wherein: The instantaneous power is modulated to a lower level at the time when the bubble is estimated to reach a maximum size.

10. The method according to claim 1, wherein: The threshold is less than or equal to the specified distance multiplied by 0.

3.

11. The method according to claim 10, wherein: The threshold is greater than or equal to 0.

12. The method according to claim 10, wherein: The laser source is a thulium fiber laser.

13. The method of claim 10, comprising emitting the plurality of laser pulses from the fiber optic cable while the fiber optic cable is disposed within a patient via a working channel of a ureteroscope.

14. A system, comprising: Laser source; and A controller coupled to the laser source, the controller comprising a processor and a memory, the memory comprising instructions that, when executed by the processor, cause the system to perform the method of any one of claims 1 to 13.

15. A non-transitory computer readable storage medium comprising instructions which, when executed by a controller of a laser system, cause the laser system to perform the method of any one of claims 1 to 13.

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