Abstract:
An apparatus for the delivery of laser light in a therapeutic environment including: a console; an optical waveguide wherein a first end of the waveguide is conffigured to expose a biological tissue to energy transmitted through the waveguide; a plurality of laser diodes housed within the console such that the light emitted by each of the diodes will illuminate a second end of the optical wave guide; and a power supply for providing electrical power to each laser diode. Preferably each laser diode is configured to produce a unique wavelength of light. The power supply provides an independently controllable output for each laser such that the exposure, both in terms of intensity and duration, to each wavelength of light may be controlled independently of the exposure to each of the other wavelengths of light.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an apparatus and method for the delivery of laser light. More particularly, but not by way of limitation, the present invention relates to an apparatus and method for the delivery of laser light for therapeutic purposes.  
           [0003]    2. Background of the Invention  
           [0004]    The use of laser light for therapeutic purposes is well known in the art. For some time relatively high power lasers have been used for surgical purposes such as cutting tissue, vaporizing tissue, cauterizing, and the like. More recently, lower power, less focused lasers have been used to stimulate biological tissue rather than destroy tissue. It has been proven that laser light, thus used, may, among other things, reduce or eliminate chronic pain, promote healing of wounds, and reduce inflammation.  
           [0005]    Generally speaking, all light striking a biological tissue is either reflected, transmitted, or absorbed. It has been found that the degree to which a particular tissue reflects, transmits, or absorbs light will vary radically with the wavelength of the light applied to the tissue. Not surprisingly, it has also been found that the biological response of a particular tissue will vary radically with the wavelength of the light applied to the tissue. Furthermore the depth to which a given wavelength of light will penetrate a particular tissue is dependent on the degree to which the tissue is transmissive at the given wavelength.  
           [0006]    A number of prior art devices have focused on the use of lasers for such treatments having a wavelength in the near infrared range. For example, U.S. Pat. No. 5,445,146 issued to Bellinger discloses the use of a Nd:YAG laser having a fundamental wavelength of 1064 nanometers with a power level between 100 milliwatts and 800 milliwatts. The Nd:YAG laser is traditionally a pumped laser, excited by an external light source. Such lasers are typically rather cumbersome, relatively expensive, and the output power is somewhat difficult to control. In addition, such lasers are only available with light output at specific wavelengths.  
           [0007]    U.S. Pat. No. 5,951,596 also issued to Bellinger discloses the use of either the Nd:YAG laser or, alternatively, an Nd:YLF laser producing energy with a wavelength of 1055 nanometers. As with the Bellinger &#39;146 device, the Bellinger &#39;596 patent discloses only the use of a pumped laser.  
           [0008]    U.S. Pat. No. 5,755,752 issued to Segal discloses the use of a semiconductor laser, specifically an Indium Gallium Arsenide (In:GaAs) diode configured for producing energy having a wavelength in the near infrared range, in the range between 1044 nanometers to 2520 nanometers, preferably at 1064 nanometers. The laser diode is relatively small allowing it to be positioned in a wand. While the Segal &#39;752 device overcomes some of the limitations of the devices using pumped lasers, it too only delivers a single wavelength of light to the patient.  
           [0009]    U.S. Pat. No. 4,930,504 issued to Diamantopoulos et. al., discloses a cluster probe for biostimulation of tissue having an array of monochromatic radiation sources of a plurality of wavelengths wherein two radiation wavelengths simultaneously pass through a single point. Diamantopoulos teaches that when a tissue is simultaneously exposed to multiple wavelengths of a light, a cumulative, and sometimes synergistic, effect is obtained. Diamantopoulos suggests that this effect is based, in part, on the “mixing” of photons.  
           [0010]    While the Diamantopoulos &#39;504 device provides a plurality of wavelengths, it does not provide independent exposure control for each wavelength. Thus, the relative exposure, both in terms of relative intensity and relative duration, between the various wavelengths of light is fixed at the time of manufacture of the device.  
           [0011]    It has been shown that the response of a particular tissue to an exposure to light varies based on the wavelength, intensity, and duration of the exposure. Thus, while there are advantages realized in delivering multiple wavelengths of light, to achieve the maximum advantage, the exposure to each particular wavelength must be tailored to, among other things: a) the particular tissue receiving treatment; b) the desired depth of penetration into the tissue for each wavelength of light; and c) the degree of stimulation required.  
           [0012]    It is thus an object of the present invention to provide a device for the delivery of laser light which provides a plurality of discrete wavelengths of light each of which strikes substantially the same area on a treated tissue.  
           [0013]    It is further object of the present invention to provide independent control for each wavelength of light such that the exposure to each wavelength, in terms of both intensity and duration, may be controlled independently from the other wavelengths of light produced.  
           [0014]    It is yet a further object of the present invention to provide a power supply for a laser delivery system which provides multiple output channels, each channel being independently controllable.  
         SUMMARY OF THE INVENTION  
         [0015]    The present invention provides an apparatus and method for the delivery of laser light in a therapeutic environment which satisfies the needs and alleviates the problems mentioned above. The inventive apparatus provides a plurality of discrete wavelengths of light wherein each wavelength is provided by a laser diode, or a group of laser diodes, and the intensity and duration of the light produced at each wavelength are independent of the intensity and duration of the light produced at other wavelengths.  
           [0016]    The inventive apparatus comprises: a console; a plurality of laser diodes housed within the console such that the light emitted by each of the diodes will illuminate the input of an optical waveguide; and a power supply for providing electrical power to each laser diode. The output of the optical waveguide is used to deliver the light to a tissue. Preferably, each diode is configured to emit a different wavelength of light.  
           [0017]    For purposes of this invention, the term “light” refers to emitted electromagnetic energy (coherent or otherwise) having a wavelength between 100 nanometers and 2600 nanometers. While only a portion of the spectrum is actually visible to the human eye, the entire range exhibits optical properties relevant to the present invention.  
           [0018]    Further objects, features, and advantages of the present invention will be apparent to those skilled in the art upon examining the accompanying drawings and upon reading the following description of the preferred embodiments. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    [0019]FIG. 1 provides a perspective view of the preferred embodiment of a system for the delivery of laser light in a therapeutic environment.  
         [0020]    [0020]FIG. 2 provides a front view of the system for the delivery of laser light in its general environment.  
         [0021]    [0021]FIG. 3 provides a block diagram of the preferred embodiment of a system for the delivery of laser light.  
         [0022]    [0022]FIG. 4 provides a perspective view of a laser diode assembly incorporated in the system for the delivery of laser light.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    The present invention provides a new apparatus and method for the delivery of laser light in a therapeutic environment wherein multiple lasers provide illumination of the input end of an optical waveguide such that the light striking the input will include a plurality of discrete wavelengths. Referring first to FIG. 1, a preferred embodiment of a system for the delivery of laser light  10  comprises: a console  20 ; a hand held wand  22 ; and an optical waveguide  24  for transmitting the laser light from the console to the wand.  
         [0024]    Referring additionally to FIGS. 2 and 3, console  20  includes: enclosure  26 ; a user interface  28  displayed on the face of enclosure  26 ; laser assembly  30  housed within enclosure  26 ; a controller  34  which controls the operation of laser assembly  30  and user interface  28 ; and power source  32  for providing electrical power to laser assembly  30  and controller  34 . An operator may provide input to the controller through user interface  28  to control the intensity and duration of each wavelength of light within predetermined limits.  
         [0025]    Preferably, user interface  28  includes a numeric display  36 , a keypad  38 , and a series of indicators  40 ,  42 ,  44 , and  46 . Indicator  40  provides a visual indication of whether the console is in a setup mode or an operational mode. In the setup mode, the operator may input the precise exposure the tissue will receive. In this mode, indicators  42 ,  44 , and  46  indicate the feature being programmed by the operator while display  36  provides visual feedback of each number entered by the operator. In the operational mode, indicators  42 ,  44 , and  46  indicate the status of the unit while display  36  provides a display of time remaining for the present treatment.  
         [0026]    As will be apparent to one of ordinary skill in the art, display  36  could be implemented in a graphical display such as a cathode ray tube or a liquid crystal display. If display  36  is a graphical display, indicators  40 ,  42 ,  44 , and  46  could be incorporated into the display.  
         [0027]    Referring now to FIG. 4, laser assembly  30  preferably comprises: a tetrahedral frame  48  having vertices  50 ,  52 ,  54 , and  56  opposite sides  58 ,  60 ,  62 , and  64  respectively; laser diode module  66  supported at vertex  50  with the output directed towards vertex  56 ; laser diode module  68  supported at vertex  52  with the output directed towards vertex  56 ; laser diode module  70  with the output likewise directed towards vertex  56 ; and fiber optic connector  72  supported at vertex  56  such that, with a fiber optic cable  24  (FIG. 1) installed at connector  72 , the light outputs from diodes  66 ,  68 , and  70  will strike the end of cable  24 .  
         [0028]    As previously stated, the term “light” is used broadly herein to refer to electromagnetic waves which exhibit optical properties consistent with the present invention and thus, the term “light” is not limited to the visible spectrum.  
         [0029]    Laser diodes, as generally known in the art, are semiconductor devices which emit coherent, monochromatic light. Monochromatic, as used herein, refers to light of substantially a single wavelength or light of a narrow range of wavelengths. Laser diodes are available in a variety of wavelengths.  
         [0030]    Referring again to FIG. 3, each diode module  66 ,  68 , and  70  preferably includes an intensity input  72  such that the power output of module  66 ,  68 , or  70  may be set with an external voltage. In the preferred embodiment, each module  66 ,  68 , or  70  is capable of outputting up to 20 watts of light. Thus, with a control voltage of zero volts, a module will produce no light. With a control voltage set at a maximum value, a module will output approximately 20 watts. For any control voltage in between zero and the maximum, a module will have an output between zero watts and 20 watts, proportional to the control voltage. Alternatively, a diode laser without an intensity input could instead be used in conjunction with a power supply having a programmable output current.  
         [0031]    As noted above, the response of a particular tissue to an exposure to light varies with the wavelength of the light. In addition, the depth of penetration into a particular tissue, or through a tissue to an underlying tissue, is likewise dependent on the wavelength of the light. In order to allow exposure to a beneficial wavelength and to allow penetration to an appropriate depth, preferably each of lasers  66 ,  68 , and  70  provides light at a wavelength different from each of the other lasers  66 ,  68 , or  70 . In the preferred embodiment laser diode  66  provides light of a wavelength between 500 nanometers and 700 nanometers. Laser diode  68  provides light of a wavelength between 700 nanometers and 900 nanometers. Finally, laser diode  70  provides light of a wavelength between 900 nanometers and 1300 nanometers. While three diodes are illustrated in the preferred embodiment, two or more laser diodes come within the scope of the invention.  
         [0032]    Controller  34  provides digital information to digital to analog converters  76 ,  78 , and  80  to provide the control voltages for diodes  66 ,  68 , and  70 , respectively. Controller  34  receives key presses from keypad  38  and drives indicators  40 ,  42 ,  44 , and  46  as well as numeric display  36 .  
         [0033]    Optical waveguide  24  is preferably a flexible, fiber optic cable. As described hereinabove, an input end  82  of fiber optic cable  24  is illuminated by the outputs of the laser diodes  66 ,  68  and  70 . The light is transmitted along waveguide  24  until it exits the opposite, output end  84 . End  84  is retained in wand  22  such that when wand  22  is placed in contact with a biological tissue, the light emanating from end  84  will illuminate the tissue in a known pattern.  
         [0034]    In an alternate embodiment (not shown), optical waveguide  24  includes a plurality of fiber optic fibers. Each fiber is terminated such that an area under treatment receives light from a plurality of angles, thus allowing simultaneous treatment of an entire area, reducing the total time required to expose the area. In addition, exposing from multiple angles would also allow a greater exposure to be delivered to an underlying tissue. Absorption in the outer tissue would occur over multiple paths, reducing the exposure of the outer tissue along any one path. However, the beams could converge at the underlying tissue to increase the power density of the light at the desired depth. For example, the plurality of fibers could terminate at a cuff such that the ends of the fibers were evenly dispersed around the circumference of the cuff. When placed around an elbow, wrist, knee, etc, the light emitted by the group of fibers would illuminate the joint from many different angels. The joint would then receive treatment from all angles simultaneously, thereby reducing the total treatment time for the patient.  
         [0035]    In operation, the controller typically activates each laser, one-at-a-time, for a predetermined period of time in a cyclic fashion. The intensity of each laser is also controlled during the activation of laser. By way of example and not limitation, a particular treatment protocol might call for a one second exposure from laser  66  at 50% of maximum power followed by a three second exposure from laser  68  at 30% power followed by a six second exposure from laser  70  at 80% power. A sequence is then repeated in a cyclic fashion until the total exposure has been produced. It should be noted that, as the laser light is absorbed by the exposed tissues, there is heating of the tissues. If such heating is excessive, the exposed cells will be damaged or destroyed. The heat produced in a given tissue at a given depth is easily predicted for a monochromatic exposure. Thus, the intensity of each wavelength may be maximized by activating the lasers individually. If multiple lasers are activated simultaneously, the power output of each laser would have to be reduced due to prevent damage to the tissue due to the cumulative light absorbed from all of the lasers. Thus, lasers  66 ,  68 , and  70  are preferably activated one-at-a-time.  
         [0036]    To deactivate a particular laser, controller  34  simply writes a zero to the appropriate digital to analog convertor  76 ,  78 , or  80 . A number of alternative methods could be used to selectively activate or deactivate a laser and such methods are within the scope of the present invention. By way of example and not limitation, such methods include providing an electronically actuable switch (e.g., a transistor, a relay, or the like) in series with each laser, providing a mechanical shutter which could be selectively actuated by the controller, or by providing an electronic shutter such as a liquid crystal device.  
         [0037]    To setup a treatment protocol, an operator enters the initial intensity of laser  66  through the keypad followed by the first duration of laser  66 . The operator then enters the initial intensity of laser  68  followed by the first duration of laser  68 . The operator next enters the initial intensity of laser  70  followed by the first duration of laser  70 . The operator then enters the total time, or number of cycles, to repeat this sequence. The operator may then enter a second sequence wherein any, or all, of the values previously entered may be modified. Additional sequences may likewise be entered following the same procedure until the entire treatment protocol has been entered. The wand is then applied to the area of the tissue to be treated and controller  34  activates each laser in accordance with the entered protocol.  
         [0038]    In addition, commonly used protocols may be permanently stored in memory within the controller to reduce the time required to setup a given protocol and to reduce the opportunity for error in entering the variable information. The operator then merely selects the preprogrammed protocol and begins the treatment.  
         [0039]    Thus, the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned above as well as those inherent therein. While presently preferred embodiments have been described for purposes of this disclosure, numerous changes and modifications will be apparent to those skilled in the art. Such changes and modifications are encompassed within the spirit of this invention.