Patent Publication Number: US-2022218415-A1

Title: System and method for treatment of human stones

Description:
BACKGROUND 
     Technical Field 
     The present disclosure relates to medical devices and methods of treatment. More specifically, the disclosure relates to systems and methods for treating human stones. 
     Description of the Related Art 
     Human stones may develop within a human body and cause symptoms, such as pain. One type of human stone is a kidney stone. Kidney stone disease, also known as urolithiasis, is when a solid piece of material (kidney stone) develops in the urinary tract. Kidney stones typically form in the kidney and leave the body in the urine stream. A small kidney stone may pass without causing symptoms, however if a kidney stone grows to more than 5 millimeters, it can cause blockage of the ureter, resulting in severe pain. When a human stone causes no symptoms, no treatment is needed. However, larger human stones may require procedures such as ureteroscopy for removal. 
     Ureteroscopy is a procedure in which a urologist positions an endoscope proximate a target area for treatment within a patient&#39;s body. Using a laser, the urologist fragments the kidney stone into smaller pieces and retracts the fragments with a basket. Known ureteroscopy treatment utilizes a holmium, e.g., a Holmium:yttrium-aluminium-garnet (Ho:YAG), laser to break up kidney stone fragments in a procedure known as lithotripsy. 
     BRIEF SUMMARY 
     The use of a high energy source, such as a laser, within a human body, e.g., in the upper urinary tract, may cause severe damage. Improper positioning of the tip of the laser delivery system, e.g., the laser fiber, may result in tissue burn, urinary tract perforation, or kidney/bladder tissue damage. Known laser lithotripsy systems are visually controlled by the surgeon performing the procedure. The surgeon&#39;s view of the target area for the laser may be obscured or affected, e.g., by stone dust or bleeding. Activation of the laser while the target area is obscured may result in activation of the laser when tissue, rather than a human stone, is in the target area. 
     Accordingly, systems and methods of identifying and distinguishing between tissue and human stones during laser lithotripsy may result in improved outcomes for treatment of patients suffering from urolithiasis. 
     According to one aspect of the disclosure, a laser lithotripsy system includes a first laser that, upon activation, produces laser light with a first wavelength. The first laser includes a first activation mode and a second activation mode. When the first laser is in the first activation mode the first laser produces a continuous wave of laser light with the first wavelength, and when the first laser is in the second activation mode the first laser produces uniformly spaced, intermittent pulses of laser light with the first wavelength. 
     The system further includes a second laser that, upon activation, produces light with a second wavelength, which is shorter than the first wavelength. The system includes a first optically powered surface positioned to receive both the light from the first laser and the light from the second laser, and the optically powered surface transmits at least 90% of the light received from the first laser and reflects at least 90% of the light received from the second laser such that the transmitted light from the first laser is superimposed with the reflected light from the second laser. 
     The system includes a waveguide, e.g., a glass fiber, positioned to receive the superimposed light from the first and second lasers and guide the superimposed light to a target, an optical detector positioned to receive light emitted by the target and measure one or more characteristics of the received light emitted by the target, and a controller. The controller is communicatively coupled to both the optical detector and the first laser such that the controller activates the first laser when the one or more measured characteristics are within a predetermined range of values and prevents activation of the first laser when the one or more measured characteristics are outside of the predetermined range of values. 
     According to another aspect of the disclosure, a method of treatment includes activating an excitation laser to produce laser light and guiding the produced laser light to a target via a waveguide. The method includes capturing light emitted from the target as a result of the laser light produced by the excitation laser impacting the target, guiding the captured light emitted from the target to an optical detector via the waveguide, and measuring one or more characteristics of the captured light emitted by the target and guided to the optical detector. The method further includes comparing the one or more measured characteristics to a predetermined set of values for each of the one or more measured characteristics, and activating a therapeutic laser when the one or more measured characteristics are within the respective predetermined set of values for each of the one or more measured characteristics, wherein activating the therapeutic laser produces a continuous wave of laser light when the therapeutic laser is in a first activation mode, and activating the therapeutic laser produces uniformly spaced, intermittent pulses of laser light when the therapeutic laser is in a second activation mode 
     According to another aspect of the disclosure, a method of treating human stones includes activating an excitation laser to produce laser light and guiding the produced laser light to a distal end of a waveguide where the produced laser light exits the waveguide. The method includes moving the distal end of the waveguide such that the produced laser light exits the waveguide and impacts a human stone, capturing light emitted from the human stone as a result of the laser light produced by the excitation laser impacting the human stone, and guiding the captured light emitted from the human stone to an optical detector via the waveguide. 
     The method further includes measuring one or more characteristics of the captured light emitted by the human stone and guided to the optical detector, determining whether the captured light was emitted by a human stone based on the measured one or more characteristics of the captured light, after determining the captured light was emitted by a human stone, activating a therapeutic laser thereby producing either a continuous wave of laser light with a first wavelength or uniformly spaced, intermittent pulses of laser light with the first wavelength, and guiding the continuous wave of laser light to the distal end of the waveguide where the continuous wave of laser light exits the waveguide and impacts the human stone with the continuous wave of light. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       In the drawings, identical reference numbers identify similar elements or acts. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not necessarily drawn to scale, and some of these elements may be arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn, are not necessarily intended to convey any information regarding the actual shape of the particular elements, and may have been solely selected for ease of recognition in the drawings. 
         FIG. 1  is a side, schematic view of a therapeutic laser system, according to an embodiment. 
         FIG. 2  is a side, schematic view of a portion of the therapeutic laser system illustrated in  FIG. 1  in use, and the system is targeting a first human stone. 
         FIG. 3  is a side, schematic view of the portion of the therapeutic laser system illustrated in  FIG. 2  in use, and the system is targeting soft tissue. 
         FIG. 4  is a side, schematic view of the portion of the therapeutic laser system illustrated in  FIG. 2  in use, and the system is targeting a second human stone. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed embodiments. However, one skilled in the relevant art will recognize that embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known structures associated with therapeutic laser systems have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments. 
     Unless the context requires otherwise, throughout the specification and claims which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense, that is as “including, but not limited to.” 
     Reference throughout this specification to “one embodiment,” “an embodiment,” or “an aspect of the disclosure” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. 
     As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. It should also be noted that the term “or” is generally employed in its broadest sense, that is as meaning “and/or” unless the content clearly dictates otherwise. 
     Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range including the stated ends of the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. 
     Aspects of the disclosure will now be described in detail with reference to the drawings, wherein like reference numbers refer to like elements throughout, unless specified otherwise. Certain terminology is used in the following description for convenience only and is not limiting. The term “plurality”, as used herein, means more than one. The terms “a portion” and “at least a portion” of a structure include the entirety of the structure. 
     The headings and Abstract of the Disclosure provided herein are for convenience only and do not interpret the scope or meaning of the embodiments. 
     Referring to  FIG. 1 , a therapeutic laser system  10  includes a housing  12  that selectively encloses an internal cavity  14  formed by the housing  12 . The system  10  includes a first laser  16  (also referred to herein as a therapeutic laser). The first laser  16 , upon activation, produces a focused beam of light  18  (i.e., laser light) with a first wavelength. Energy, typically via a pump  20 , is supplied to a lasing medium  22 . The supplied energy causes electrons within atoms of the lasing medium  22  to become “excited” and increase their energy level. Once these “excited” electrons return to their “non-excited” ground state (or energy level), energy is released in the form of photons. These photons are reflected back and forth through the lasing medium  22  by a pair of mirrors. A first mirror  24  of the pair of mirrors is a total reflector, which reflects all of the photons that impact the first mirror  24  back toward the lasing medium  22 . A second mirror  26  of the pair of mirrors is a partial reflector, which reflects a portion of the photons that impact the second mirror  26  back toward the lasing medium  22 , while allowing a focused beam of the photons to pass through the second mirror  26  and exit the laser  16 , thereby forming the focused beam of light  18 . 
     Holmium-based lasers are known for their use in a number of therapeutic applications. A holmium-based laser includes holmium as the lasing medium. However, there are several drawbacks to holmium-based lasers. Medical holmium-based lasers are pumped by flashlamps, which operate in a pulsed mode, thus holmium-based lasers produce a pulsed beam of laser light that includes intervals of high peaks of power separated by intervals of relatively low (or no) power. For example, a holmium-based laser may operate at 30 Hertz (Hz), such that the beam of light produced over one second includes 30 peaks of power separated by 30 intervals of low (or no) power of equal length. Additionally, the frequency of holmium-based lasers is high enough to cause retropulsion (i.e., movement) of human stones that are impacted by beam of light created by a holmium-based laser. For example, a Holmium:yttrium-aluminium-garnet (Ho:YAG) laser produces a beam of light with a wavelength of 2,100 nanometers (nm). 
     According to one embodiment, the focused beam of light  18  produced by the first laser  16  of the therapeutic laser system  10  may be in the form of a continuous wave. As used herein a continuous wave is an alternative form to a pulsed laser as described above. Rather than regularly spaced intervals of peaks of high power spaced by intervals of low (or no) power, a continuous wave laser maintains a steady output of power over an amount of time (e.g., a second or greater) until the laser producing the continuous wave is affirmatively deactivated (e.g., by a user or a controller). A continuous wave laser may be activated and deactivated, but the intervals between such activations are not of equal length. 
     The use of a continuous wave of the focused beam of light  18  results in less energy being needed to achieve the same therapeutic result as would be required to operate a pulsed beam. Additionally, the continuous wave of the focused beam of light  18  transfers less heat to a target impacted by the focused beam of light  18 . 
     According to one embodiment, the focused beam of light  18  produced by the first laser  16  of the therapeutic laser system  10  may have a wavelength that is shorter than 2,100 nm. For example, a thulium:yttrium-aluminium-garnet (Tm:YAG) laser produces a focused beam of light with a wavelength of 2,010 nm. 
     A thulium laser may be pumped by laser diodes, which may operate at a higher wall-plug efficiency compared to the flashlamps of a holmium laser, thus result in a higher efficiency for a thulium laser. Thulium lasers, however, present challenges related to their engineering and construction. Specifically, the optical focusing design related to a thulium laser used in the therapeutic laser system  10  may be more complex and/or expensive than a holmium laser, as the thulium laser may be operable in both a continuous wave mode and a pulsed mode. Thus, a thulium laser may require the development of a complex focusing lens system as well as a resonator/cavity design that each meet the operating criteria for multiple modes of laser operation. Thulium lasers may produce laser light with a wavelength between 1800 nm and 2200 nm. 
     The focused beam of light  18  produced by the first laser  16  is guided to a target  17 . As shown in the illustrated embodiment, the system  10  may include a waveguide  30  (e.g., a laser fiber), with an internal cavity which guides the focused beam of light  18  along a length of the waveguide  30 . The waveguide  30  may include a distal end  32  at which the focused beam of light  18  exits the internal cavity of the waveguide  30 . The waveguide  30  may be flexible so that the distal end  32  is moveable (e.g., relative to a proximal end  34  of the waveguide  30  that is attached to the housing  14 ) to be positioned adjacent the target  17 . 
     According to one embodiment, the target  17  may be located within a human body  36 . For example, the target  17  may include one or more urinary stones within a patient&#39;s urinary tract. Thus, the system  10  may include an endoscope  38  (e.g., a cystoscope, a ureteroscope, a renoscope, a nephroscope, etc.) and the waveguide  30  may be sized to fit within the endoscope  38  during insertion of the endoscope  38  into the patient&#39;s body and advancement to the target  17 . 
     During advancement of the endoscope  38  and the enclosed waveguide  30 , the distal end  32  may be enclosed within an internal cavity of the endoscope  38 , thus protecting the distal end  32  from damage (e.g., due to contact with body tissue). Upon arrival at the target  17 , the waveguide  30  may be advanced within the endoscope  38  such that the distal end  32  is exposed as shown in the illustrated embodiment. The advancement of the waveguide  30  may help prevent the focused beam of light  18  from impacting and potentially damaging the endoscope  38 . 
     With the distal end  32  of the waveguide  30  pointed at the target  17 , activation of the first laser  16  results in the focused beam of light  18  impacting the target  17 . According to one embodiment, the target  17  includes a human stone  40  (e.g., a urinary stone), and sustained impact of the focused beam of light  18  with the human stone  40  results in the human stone  40  breaking into multiple fragments, which due to their smaller size are easier to remove from the patient&#39;s body  36 . 
     The system  10  may include a waveguide coupler  42 , which couples the proximal end  34  of the waveguide  30  to the housing  12 . 
     The system  10  may further include a second laser  50 . As shown both the first laser  16  and the second laser  50  may be enclosed within the internal cavity  14  of the housing  12 . The close proximity of the first laser  16  and the second laser  50  may result in smaller losses and thus better efficiency of the system  10 . The second laser  50 , upon activation, produces a focused beam of light  52  with a second wavelength. 
     According to one embodiment, the second laser  50  is an excitation laser (e.g., a green excitation laser that produces a focused beam of light  52  with a wavelength of 532 nm). An excitation laser, as used herein, refers to a laser suitable for use in a laser-induced fluorescence (LIF) application. LIF involves the excitation of an atom or molecule to a higher energy level upon the absorption of laser light, such as the focused beam of light  52  of the second laser  50 . Some time after the absorption of the laser light the energy is released in the form of emission of light from the atom or molecule. 
     The system  10 , according to one embodiment, directs the focused beam of light  52  of the second laser  50  to enter the waveguide  30 , which then guides the focused beam of light  52  to the distal end  32  where the focused beam of light  52  exits the waveguide  30  and impacts the target  17 . If both the first laser  16  and the second laser  50  are activated at the same time, the focused beam of light  18  and the focused beam of light  52  may coincide. It will be appreciated that the focused beams of light are shown as separate elements within the drawings for clarity purposes. 
     The second laser  50  may include a single mode (e.g., pulsed or continuous wave). According to one embodiment, the second laser  50  may include a plurality of modes (e.g., pulsed and continuous wave). The pulsed mode of the second laser  50  may include multiple settings with varied pulsed durations. According to one embodiment, the focused beam of light  52  of the second laser  50  has a second wavelength of between 500 nm and 600 nm, an output power of between 40-80 millijoules (mJ), a pulse duration of between 1 and 2 microseconds (μs), or any combination thereof. 
     Analyzing the reaction of the target  17  to the impact of the focused beam of light  52  of the second laser  50  may allow the target  17  to be identified or at least classified without direct, visual observation. For example, a human stone may emit a fluorescence signal with an amplitude that is higher (e.g., at least three times higher than an amplitude of a fluorescence signal of either urinary tract tissue or components of an endoscope. 
     A fluorescence signal  54  emitted by the target  17  in response to impact of the focused beam of light  52  of the second laser  50  may travel in the opposite direction of the focused beam of light  52  of the second laser  50 , such that the fluorescence signal  54  enters the distal end  32  of the waveguide  30  and exits the proximal end  34  into the internal cavity  14  of the housing  12 . Upon entry to the housing  12  the fluorescence signal  54  may be directed to an optical detector  56  of the system  10 . The fluorescence signal  54  may have a third wavelength (or range of wavelengths) that is shorter than the first wavelength of the focused beam of light  18  and longer than the focused beam of light  52 . According to one embodiment, the third wavelength is between 550 nm and 900 nm. 
     The optical detector  56  measures one or more characteristics of the fluorescence signal  54  emitted by the target  17 . According to one embodiment, the one or more characteristics include an intensity of the fluorescence signal  54 , a spectrum of the fluorescence signal  54 , or both the intensity and the spectrum of the fluorescence signal  54 . For example, the optical detector  56  may measure the amplitude, the wavelength, or both of the fluorescence signal  54 . 
     A first, relatively low, amplitude may indicate that the fluorescence signal  54  is being emitted by human tissue (e.g., urinary tract tissue), thus indicating that the target  17  is human tissue. A second, relatively high, amplitude (for example at least twice the amplitude of the first amplitude) may indicate that the fluorescence signal  54  is being emitted by a human stone, thus indicating that the target  17  is a human stone. The measured one or more characteristics of the fluorescence signal  54  emitted by the target  17  may provide additional information, such as the main component of the target  17  (i.e., the specific type of human stone). 
     The system  10  may further include a controller  60  communicatively coupled to both the optical detector  56  and the first laser  16 . The controller  60  receives data from the optical detector  56  identifying whether the target  17  is one that is meant to be impacted by the focused beam of light  18  (e.g., a human stone) or one that is not meant to be impacted by the focused beam of light  18  (e.g., tissue of the patient or a component of the endoscope  38 ). Upon receipt of data that identifies the target  17  as an object not meant to be impacted by the focused beam of light  18 , the controller  60  prevents activation of the first laser  16  until data is received by the controller  60  that the target  17  is one that is meant to be impacted by the focused beam of light  18 . Thus, according to one embodiment, the controller  60  is able to both activate the first laser  16  when the one or more measured characteristics of the fluorescence signal  54  are within a predetermined range of values (e.g., that identify the target  17  as a human stone) and prevent activation of the first laser  16  when the one or more measured characteristics are outside of the predetermined range of values (e.g., thus identifying the target  17  as human tissue, an endoscope, or an object other than a human stone). 
     The system  10  may further include a user interface  62  that includes a display  64 , input controls  66 , or both. The display  64  may show operational parameters of the system  10  including, but not limited to, the status (e.g., activated/not activated, continuous wave mode/pulse mode, etc.) of the first laser  16 , the status of the second laser  50 , the identification/classification of the target  17 , etc. The input controls  66  may allow a user of the system  10  to change one or more of the operational parameters of the system  10  including, but not limited to, the status (e.g., activated/not activated, continuous wave mode/pulse mode, etc.) of the first laser  16 , the status of the second laser  50 , etc. 
     The system  10  may be mobile. As shown, the housing  12  may be mounted on wheels  68  so as to allow a user of the system  10  to change the location of the system  10 . 
     The system  10  may include one or more optically powered elements (e.g., a lens, a mirror, etc.) that facilitate guiding the focused beam of light  18  and the focused beam of light  52  into the waveguide, and guiding the fluorescence signal  54  to the optical detector  56 . As shown in the illustrated embodiment, the system  10  may include a first optically powered element  70  positioned within the internal cavity  14  of the housing  12  such that both the focused beam of light  18  and the focused beam of light  52  impact the first optically powered element  70 . 
     According to one embodiment, the first optically powered element  70  is structured so as to be highly transmissive for light of the first wavelength and highly reflective for light of the second wavelength. As shown, the focused beam of light  18  from the first laser  16  passes through the first optically powered element  70  without significant alteration or losses. For example, according to one embodiment at least 90% of the focused beam of light  18  that impacts the first optically powered element  70  exits the first optically powered element  70  along the same direction with which it entered. 
     As shown, the focused beam of light  52  from the second laser  50  reflects off of the first optically powered element  70  without significant losses. For example, according to one embodiment at least 90% of the focused beam of light  52  that impacts the first optically powered element  70  reflects off of the first optically powered element  70  and is superimposed (or coincident with) the focused beam of light  52  as it exits the first optically powered element  70 . According to one embodiment, the first optically powered element  70  is highly transmissive of light with a wavelength of between 2000 nm and 2200 nm, and the first optically powered element  70  is highly reflective of light with a wavelength between 500 nm and 900 nm. 
     The system  10  may include a second optically powered element  72  positioned within the internal cavity  14  of the housing  12  such that both the focused beam of light  52  and the fluorescence signal  54  impact the second optically powered element  72 . 
     According to one embodiment, the second optically powered element  72  is structured so as to be highly transmissive for light of the third wavelength (i.e., the fluorescence signal  54 ) and highly reflective for light of the second wavelength (i.e., the focused beam of light  52  of the second laser  50 ). As shown, the fluorescence signal  54  passes through the second optically powered element  72  without significant alteration or losses. For example, according to one embodiment at least 90% of the fluorescence signal  54  that impacts the second optically powered element  72  exits the second optically powered element  72  and enters the optical detector  56 . 
     As shown, the focused beam of light  52  from the second laser  50  reflects off of the second optically powered element  72  without significant losses. For example, according to one embodiment at least 90% of the focused beam of light  52  that impacts the second optically powered element  72  reflects off of the second optically powered element  72  and is guided toward the waveguide  30 , for example via the first optically powered element  70 . According to one embodiment, the second optically powered element  72  is highly transmissive of light with a wavelength of between 550 nm and 900 nm, and the second optically powered element  72  is highly reflective of light with a wavelength between 500 nm and 540 nm. 
     Referring to  FIGS. 1 to 4  a method of treating human stones (e.g., urinary stones) includes activating the second laser  50  to produce the focused beam of light  52  and guiding the focused beam of light  18  to the distal end  32  of the waveguide  30  where the focused beam of light  18  exits the waveguide  30 . As shown in  FIG. 2 , the method includes moving the distal end  32  of the waveguide  30  such that the focused beam of light  52  exits the waveguide  30  and impacts a first human stone  40   a.    
     The method may further include capturing light emitted (e.g., the fluorescence signal  54 ) from the first human stone  40   a  as a result of the focused beam of light  52  impacting the first human stone  40   a , and then guiding the captured light emitted from the first human stone  40   a  to the optical detector  56  via the waveguide  30 . 
     The method may include measuring one or more characteristics of the fluorescence signal  54  and determining whether the fluorescence signal  54  was emitted by a human stone based on the measured one or more characteristics of the fluorescence signal  54 . After determining the fluorescence signal  54  was emitted by a human stone, the method may include activating (e.g., via the controller  60 ) the first laser  16  thereby producing the focused beam of light  18  in the form of a continuous wave. The method further includes guiding the focused beam of light  18  to the distal end  32  of the waveguide  30  where the focused beam of light  18  exits the waveguide  30  and impacts the first human stone  40   a.    
     The method may include impacting the first human stone  40   a  with the continuous wave of the focused beam of light  18  until the first human stone  40   a  breaks into multiple fragments (e.g., a first fragment  40   a ′ and a second fragment  40   a ″). The fragments may be discrete elements of a smaller size than the whole first human stone  40   a . Breaking the first human stone  40   a  may include pulverizing the first human stone  40   a  such that at least portions of the first human stone  40   a  are reduced to dust. 
     After breaking the first human stone  40   a  into multiple fragments, moving one or more of the fragments, the distal end  32  of the waveguide  30 , or both one or more of the fragments and the distal end  32  of the waveguide  30  such that the focused beam of light  52  of the second laser  50  exits the waveguide  30  and impacts a target other than one of the multiple fragments of the first human stone  40   a.    
     As shown in  FIG. 3 , the system  10  may define a treatment space  80 . The treatment space  80  may be the volume within which the focused beam of light  18  of the first laser  16  is effective at delivering the intended therapeutic treatment (e.g., fragmenting a human stone). According to one embodiment, the treatment space  80  extends out from the distal end  32  of the waveguide  30  (e.g., between 30 to 300 microns (μm)) and is bounded by perimeter that corresponds to a core diameter of the waveguide  30  (e.g., between 10-20 μm). 
     When the treatment space  80  is devoid of a human stone, the target  17  may be human tissue  41 , a portion of the endoscope  38 , or nothing at all (i.e., air) such that the fluorescence signal  54  may be minimal or absent entirely. Thus, the method may include attempting to capture the fluorescence signal  54  when the treatment space  80  is devoid of a human stone. If the fluorescence signal  54  is absent or of a relatively low amplitude so as to indicate that the treatment space  80  is devoid of a human stone, the method includes preventing activation of the first laser  16 . 
     The method may further include moving the distal end  32  of the waveguide  30  until a second human stone  40   b  is located within the treatment space  80 , as shown in  FIG. 4 . When the second human stone  40   b  is located within the treatment space  80 , the focused beam of light  52  impacts the second human stone  40   b  causing a fluorescence signal  54  to be emitted by the second human stone  40   b . The fluorescence signal  54  is captured by the waveguide  30  and guided to the optical detector  56 , which identifies the fluorescence signal  54  as being emitted by a human stone. Upon identification of the second human stone  40   b  within the treatment space  80 , the first laser  16  is activated producing the focused beam of light  18 , which is guided to the second human stone  40   b.    
     According to one embodiment, the first laser  16  includes multiple modes of activation (e.g., pulsed or continuous wave). The method may include selecting the second mode and activating the first laser  16  to produce intermittent pulses of the focused beam of light  18 . 
     The above description of illustrated embodiments, including what is described in the Abstract, is not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. Although specific embodiments of and examples are described herein for illustrative purposes, various equivalent modifications can be made without departing from the spirit and scope of the disclosure, as will be recognized by those skilled in the relevant art. 
     Many of the methods described herein can be performed with variations. For example, many of the methods may include additional acts, omit some acts, and/or perform acts in a different order than as illustrated or described. The various embodiments described above can be combined to provide further embodiments. 
     These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.