Patent Publication Number: US-2004054386-A1

Title: Device for the treatment of muscle or joint pain

Description:
RELATED APPLICATIONS  
     [0001] This application claims priority under 35 U.S.C. §119 to U.S. Provisional Patent Application No. 60/408,216 filed Sep. 4, 2002. 
    
    
     [0002] This invention was made with U.S. Government support under Contract DAAH01-03-C-R-120 awarded by the Defense Advanced Research Projects Agency (DARPA). The U.S. Government has certain rights in this invention. 
    
    
     
       BACKGROUND OF THE INVENTION  
       [0003] This invention relates to a device for the treatment of muscle or joint pain. The device includes arrays of optoelectronic devices, such as light emitting diodes, that emit radiation suitable for the treatment of muscle or joint pain.  
       [0004] Biostimulation is a method of using monochromatic light to deliver photons to cytochromes in the mitochondria of cells. Cytochromes are light-sensitive organelles that act as an electron transport chain, converting energy derived from the oxidation of glucose into adenosine triphosphate (ATP)—the mitochondria&#39;s fuel. By directly stimulating cytochromes with monochromatic light, it is believed that more fuel is pumped into the mitochondria of cells, increasing the energy available to the cells. Increasing the energy available to the cell is believed to help relieve pain.  
       [0005] By pumping more fuel into the mitochondria, biostimulation is believed to increase the respiratory metabolism of many types of cells. The monochromatic light provided by biostimulation is believed to be absorbed by the mitochondria of many types of cells where it stimulates energy metabolism in muscle and bone, as well as skin and subcutaneous tissue. Specifically, biostimulation is believed to result in fibroblast proliferation, attachment and synthesis of collagen, procollagen synthesis, macrophage stimulation, a greater rate of extracellular matrix production, and growth factor production. Specifically, the growth factors that are produced include keratinocyte growth factor (KGF), transforming growth factor (TGF), and platelet-derived growth factor (PDGF).  
       [0006] One method of providing biostimulation is the use of lasers. Lasers can provide monochromatic light for the stimulation of tissues resulting in increased cellular activity during the healing process. Specifically, these activities are believed to include fibroblast proliferation, growth factor synthesis, collagen production, and angiogenesis.  
       [0007] Using lasers to provide monochromatic light for biostimulation has several disadvantages. First, lasers are limited by their wavelength capabilities. Specifically, the combined wavelengths of light optimal for treating muscle and joint pain cannot be efficiently produced, because laser conversion to near-infrared wavelengths is inherently costly. Second, lasers are limited by their beam width. A limited beam width results in limitations in the area which may be treated by lasers. Third, and most importantly, along with the production of monochromatic light, lasers produce a significant amount of heat. As a result of the production of heat, lasers cannot be used for extended treatment times or in applications in which the patient cannot tolerate heat.  
       SUMMARY OF THE INVENTION  
       [0008] The invention provides a device for treating a medical condition, such as muscle or joint pain, using an array of optoelectronic devices, such as light-emitting diodes (LEDs). In one embodiment of the invention, a device for treating muscle or joint pain is a self-contained, self-powered, hand-held device that can emit radiation having a light intensity of at least approximately 30 milliwatts per centimeter squared. The device includes a housing, a portable power source disposed in the housing, and one or more optoelectronic devices disposed in the housing and coupled to the portable power source. The device also includes a cooling system disposed in the housing. The cooling system can dissipate the heat generated by the optoelectronic devices.  
       [0009] According to one embodiment of the method of the invention, a user positions a housing including optoelectronic devices adjacent to a muscle and/or ajoint of a patient. The user irradiates the muscle and/or the joint with radiation emitted by the optoelectronic devices. The emitted radiation has a wavelength suitable for the treatment of muscle and/or joint pain. The heat produced by the optoelectronic devices is dissipated through the housing.  
       [0010] According to another embodiment of the method of the invention, a user positions a housing adjacent to at least one of a muscle and a joint of a patient. A plurality of optoelectronic devices are disposed in the housing. The user irradiates the muscle and/or the joint with radiation emitted by the plurality of optoelectronic devices for a treatment session having a first duration. The plurality of optoelectronic devices are allowed to dissipate heat for a cooling-down period having a second duration, and the plurality of optoelectronic devices are prevented from emitting radiation during the cooling-down period. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0011] These and other features of the present invention will be apparent to those skilled in the art from the following description of the preferred embodiments and the drawings, in which:  
     [0012]FIG. 1 is a top perspective view of a hand-held device according to one embodiment of the present invention.  
     [0013]FIG. 2 is a bottom perspective view of the hand-held device of FIG. 1.  
     [0014]FIG. 3 is a side elevational view of the hand-held device of FIG. 1.  
     [0015]FIG. 4 is a side elevational view of the hand-held device of FIG. 1 with a power source compartment cover removed.  
     [0016]FIG. 5 is an exploded side elevational view of the hand-held device of FIG. 1.  
     [0017]FIG. 6 is a perspective view of a heat sink, a circuit board, and a ceramic assembly of the hand-held device of FIG. 1.  
     [0018]FIG. 7 is a side elevational view of the heat sink, the circuit board, and the ceramic assembly of FIG. 6.  
     [0019]FIG. 8 is a side elevational view of the heat sink and the ceramic assembly of FIG. 6.  
     [0020]FIG. 9 is a side elevational view of the heat sink and the circuit board of FIG. 6.  
     [0021]FIG. 10 is a schematic diagram of a control circuit for use with the hand-held device of FIG. 1.  
     [0022]FIG. 11 is a current source module of the control circuit of FIG. 10.  
     [0023]FIG. 12 is a voltage reference module of the control circuit of FIG. 10.  
     [0024]FIG. 13 is a power control module of the control circuit of FIG. 10.  
     [0025]FIG. 14 is a power-on reset module of the control circuit of FIG. 10.  
     [0026]FIG. 15 is a temperature sensing module of the control circuit of FIG. 10.  
     [0027]FIG. 16 is a battery voltage sensing module of the control circuit of FIG. 10. 
    
    
     DETAILED DESCRIPTION  
     [0028] In each of the embodiments of the present invention, at least one optoelectronic device is used to emit radiation for the treatment of a medical condition, such as for the treatment or relief of muscle or joint pain. The optoelectronic devices can be substantially monochromatic, double-heterojunction, Gallium-Aluminum-Arsenide (GaAlAs) LEDs of the type manufactured by Showa Denkoa or Stanley, both of Japan, or by Hewlett-Packard of Palo Alto, Calif. In some embodiments, the optoelectronic devices are connected together in a manner described in U.S. Pat. No. 5,278,432 issued Jan. 11, 1994 to Ignatius et al., which is incorporated herein by reference.  
     [0029] In some embodiments, the LEDs emit radiation at approximately 670 nanometers (nm)±approximately 15 nm, which is believed to be an optimal wavelength for relieving and potentially treating muscle and/or joint pain. Some embodiments of the invention include an array of LEDs that emit radiation. Other wavelengths may also be suitable for relieving and treating muscle and/or joint pain or for treating other medical conditions, such as approximately 300 nm to 950 nm, and more specifically, approximately 640 nm to 700 nm. Moreover, as further research is conducted, other wavelengths may be found to be effective. However, the present invention is not limited to the use of any specific wavelength. In some embodiments, the LEDs are wavelength specific in that the LEDs emit a certain wavelength when provided with power. For example, one or more wavelength-specific LEDs emitting radiation at 670 nm can be assembled onto a circuit board or any other suitable substrate in order to provide a hand-held device  10  that emits radiation at a central wavelength of 670 nm.  
     [0030] In addition to the wavelength of the radiation emitted by the LEDs, the following parameters should be considered to optimize the stimulative effect of the LEDs on biological tissues: the energy density required for activation (E/a) act , the light intensity I stim , and the total irradiation time Δt tot . The parameters are interrelated according to the following equation,  
     ( E/a ) act   =I   stim   ×Δt   tot    
     [0031] where intensities necessary for stimulation I stim  should surpass a threshold intensity I o , i.e.,  
     I stim ≧I o .  
     [0032] Light intensities lower than threshold values I o  typically may not produce biostimulatory effects, even under prolonged irradiation times Δt tot .  
     [0033] It is believed that the optimal energy densities for cellular activation (E/a) act  are approximately 4 to 8 Joules per centimeter squared. The light intensity (I stim ) of the radiation emitted by the LEDs may be approximately 30 to 80 milliwatts (mW) per centimeter squared, and up to approximately 200 milliwatts per centimeter squared. In one embodiment, the LEDs emit radiation at an intensity of approximately 50-60 milliwatts per centimeter squared. In some embodiments, the irradiation time Δt tot  per treatment period is about 88 seconds ±8 seconds.  
     [0034] In some embodiments, the LEDs emit radiation having a relatively constant light intensity over a treatment area. In one embodiment, the light intensity varies by less than about 30% over a treatment area of approximately ten square centimeters. For example, 4.8 LEDs per centimeter squared for a total of 48 LEDs can provide a relatively constant light intensity over a treatment area of approximately ten square centimeters. However, fewer than 4.8 LEDs per centimeter squared can be used if the LEDs emit radiation at a higher light intensity.  
     [0035]FIGS. 1 and 2 illustrate a hand-held device  10  according to one embodiment of the invention. As shown in FIG. 2, the hand-held device  10  includes one or more LEDs  12  (e.g., an array of LEDs) that can emit radiation toward a patient. The hand-held device  10  includes a housing  14  that supports the LEDs  12 . The housing  14  can be constructed of a polycarbonate ABS alloy or any other suitable packaging polymer. In some embodiments, the housing  14  provides a sealed, self-contained enclosure for the hand-held device  10  so that no contaminates can enter the hand-held device  10 . In other embodiments, the housing  14  includes vents so that air can pass through the housing  14  to cool the LEDs  12  or so that a fan (not shown) can be included in the housing  14  to cool the LEDs  12 . If a fan is included in the housing  14 , the hand-held device  10  can be powered by a portable power source within the housing  14  or by an AC power source (e.g., a power cord, a transformer, and/or an electrical plug for connection to a wall outlet). In some embodiments, a fan can provide continuous cooling, without a cooling-down period in which the LEDs  12  cannot be illuminated. A heat sink having fins (not shown) can also be used in conjunction with a fan to cool the LEDs  12 .  
     [0036] As also shown in FIG. 2, the hand-held device  10  can include a cover plate  16  suitable to electrically isolate the patient from the LEDs  12 . The cover plate  16  can be constructed of any suitable transparent or semi-transparent material. As shown in FIG. 1, the housing  14  can include one or more user-manipulatable controls  18  (e.g., a START button and a STOP button) and one or more indicator lights  20  (e.g., a LOW BATTERY light and a DELAY light).  
     [0037] As shown in FIG. 3, the housing  14  can include a raised portion  22  within which the LEDs  12  can be positioned. The raised portion  22  can include a circular aperture  23  (as shown in FIG. 2), or an aperture having any other suitable shape, through which the LEDs  12  can emit radiation. The cover plate  16  can be positioned within the raised portion  22  over the LEDs  12 . The cover plate  16  can be coupled to the raised portion  22  with an ultraviolet epoxy or with any other suitable adhesive or fastener.  
     [0038] As shown in FIGS. 1 and 5, the housing  14  can include a top cover  24  and a bottom or aperture cover  26 . The bottom cover  26  can include or can be coupled to the raised portion  22 . As shown in FIGS. 4 and 5, the housing  14  can include a power source compartment cover  28  removably coupled adjacent to the bottom cover  26  with a screw  30 . The hand-held device  10  can be powered by any suitable power source, including rechargeable or non-rechargeable, standard or non-standard batteries; AC power sources or connections; fuel cells; and other portable power sources. In one embodiment, the power source is eight standard AA-sized batteries which can be held together within the housing  14  by a battery holder.  
     [0039] As shown in FIG. 5, the hand-held device  10  can include a cooling system in the form of a heat sink  32 . The heat sink  32  can be constructed of aluminum, an aluminum alloy, or any other material suitable for dissipating heat. The heat sink  32  can have a total mass suitable for dissipating heat from the LEDs  12  during a cooling-down period of a reasonable duration (e.g., approximately 88 seconds after a single treatment session or several seconds longer after more than one consecutive treatment session). In one embodiment, the total mass of the heat sink  32  allows the hand-held device  10  to operate for eight to ten treatment sessions before the cooling-down period of 88 seconds must be extended (as will be described below with respect to FIGS.  10 - 16 ). The total mass of the heat sink  32  can also be designed so that the total weight of the hand-held device  10  (preferably including the batteries or other portable power source) is about one pound.  
     [0040] The heat sink  32  can be coupled to a first side  33  of a ceramic assembly  34  by one or more screws  38  (e.g., three nylon screws) or by a suitable thermal adhesive. The LEDs  12  (e.g., an array of several LEDs) can be coupled to a second side  35  of the ceramic assembly  34 . The ceramic assembly  34  is thermally conductive in order to transfer heat emitted by the LEDs  12  to the heat sink  32 , but the ceramic assembly  34  is not electrically conductive.  
     [0041] In other embodiments, the cooling system of the hand-held device  10  can include a thin-film insulator (not shown) coupled to an aluminum substrate (not shown). A suitable thin-film insulator is Kapton® manufactured by E. I. Du Pont De Nemours and Company Corporation.  
     [0042] As shown in FIG. 5, the heat sink  32  can also be coupled to a circuit board  36  by any suitable fasteners, such as screws  39  positioned through holes  41  in the circuit board  36 . The heat sink  32  can include one or more elevated portions (or bosses or stand-offs)  37  that closely or directly contact one or more components mounted on the circuit board  36  (e.g., a temperature sensor and/or various transistors, as are described below with respect to FIGS.  10 - 16 ) in order to dissipate heat from those particular components. The elevated portions  37  can also create an air gap between the heat sink  32  and the circuit board  36  to further cool the components mounted on the circuit board  36 . The elevated portions  37  can be integrally molded with the heat sink  32 . The circuit board  36  can be connected to the LEDs  12  by a conductor jumper  40  (e.g., a twelve-conductor jumper in one embodiment or by two or more wires or groups or wires in other embodiments). The circuit board  36  can be connected to one or more batteries (not shown) or to any other suitable power source by a positive connection  43  (e.g., VBatt) and can be grounded with a ground wire  45  (as shown in FIG. 9). The positive connection  43  can be connected to one or more battery clips  42 . The battery clips  42  can be attached to a partition wall  44  included in or coupled to the bottom cover  26 . In some embodiments, when batteries are inserted into the housing  14 , the battery clips  42  connect the positive ends of the batteries to the positive connection  43 .  
     [0043] As also shown in FIG. 5, the bottom cover  26  can include one or more heat sink support members  46 . The heat sink support members  46  can be positioned within corresponding recesses  48  on the edges of the heat sink  32 . The top cover  24  of the housing  14 , the bottom cover  26  of the housing  14 , the heat sink  32 , the ceramic assembly  34 , and the circuit board  36  can be secured to one another by one or more suitable fasteners (e.g., screws  50 ), by suitable adhesives, or by a combination of fasteners and adhesives.  
     [0044]FIGS. 6 and 7 illustrate the LEDs  12 , the heat sink  32 , the ceramic assembly  34 , and the circuit board  36  as assembled, but not positioned inside of the top cover  24  and the bottom cover  26  of the housing  14 . FIG. 7 also illustrates a push button  52  coupled to the circuit board  36  (only one push button is shown from the side elevational view, although some embodiments include two push buttons for the two user-manipulatable controls  18  shown in FIG. 1). In addition, FIG. 7 illustrates an indicator light  54  (only one indicator light is shown from the side elevational view, although some embodiments include two indicator lights for the two indicator lights  20  shown in FIG. 1). FIG. 8 illustrates the LEDs  12  coupled to the ceramic assembly  34  and the heat sink  32 . FIG. 9 illustrates the circuit board  36  coupled to the heat sink  32 .  
     [0045] In some embodiments, the hand-held device  10  does not include a cooling system (i.e., no heat sink or fan). In these embodiments, the LEDs  12  are mounted to the circuit board  36  which is positioned inside of the housing  14 . The LEDs  12  can be allowed to emit as much heat as possible without an additional cooling system.  
     [0046]FIG. 10 is a schematic diagram of a control circuit  100  for use with the hand-held device  10 . The components and connections of the control circuit  100  can be included in and/or mounted to the circuit board  36  described above. The control circuit  100  can include a current source module  102  that drives the LEDs  12  (via connections M through T). The current source module  102  can be connected to a voltage reference module  104  (via a connection A). The voltage reference module  104  can be connected to a battery voltage sensing module  106  (via connections C and D), a temperature sensing module  108  (via connections B and E), and a power-on reset module  110  (via a connection F). The power-on reset module  110  can be connected to a power control module  112  (via a connection G). The battery voltage sensing module  106  can be connected to the power control module  112  (via a connection H). The power control module  112  can be connected to the LEDs  12  (via a connection I). The temperature sensing module  108  can be connected to the power-on reset module  110  (via a connection J). The battery voltage sensing module  106  can be connected to the power-on reset module  110  (via a connection K) and to the temperature sensing module  108  (via a connection L). Particular embodiments of each of these modules will be described in detail with respect to FIGS.  11 - 16 .  
     [0047]FIG. 11 illustrates one embodiment of the current source module  102 . The current source module  102  can include eight current sources  114  resulting in eight channels being connected to the LEDs  12  (via connections M through T) in order to provide eight control signals or driving currents to the LEDs  12 . In one embodiment, each channel is connected to six LEDs (e.g., two parallel strings of three LEDs in each string) for a total of 48 LEDs. In other embodiments, the LEDs  12  can be connected in any suitable manner, such as all of the LEDs being connected in series or all of the LEDs being connected in parallel, or any other combination of strings of LEDs being connected in series and in parallel. In some embodiments, any number of LEDs  12  can be connected in any manner as long as all of the LEDs can be turned ON and turned OFF at the same time. As shown in FIG. 10, each set of six LEDs can be connected to a positive power source V+(via the connection I) from the power control module  112 . The current sources  114  can provide approximately 98 milliamps to the LEDs  12  connected to each one of the eight channels and approximately 49 milliamps to each string of three LEDs. Each one of the current sources  114  can include an operational amplifier  116 . In one embodiment, two quad operational amplifiers can be used for the eight current sources  114  (a first quad operational amplifier includes U 9 A-U 9 D and a second quad operational amplifier includes U 10 A-U 10 D). Suitable operational amplifiers are Model No. LM324 operational amplifiers manufactured by National Semiconductor.  
     [0048] The output of each operational amplifier  116  can be connected to the gate of a transistor  118  (Q 8 -Q 15 ). The drain of the transistor  118  can be connected to one set of six LEDs  12 . Suitable transistors are Model No. TN0104 n-channel MOSFET transistors manufactured by Supertex. In each current source  114 , a sensing resistor  120  (e.g., 5 Ohm resistors R 20 -R 27 ) can be connected to a first input of the operational amplifier  116  and to the source of the transistor  118 . The transistor  118  acts as a switch between the LEDs  12  and the positive power source V+ from the power control module  112 . The sensing resistor  120  can determine how much current is being provided to the transistor  118  and the LEDs  12  at a test point (TP 8 -TP 15 ). A second input of the operational amplifier  116  can be connected to a common node or test point TP 5  in the voltage reference module  104  (at connection A as shown in FIG. 12).  
     [0049] Referring to FIGS. 11 and 12, the voltage at test point TP 5  provides a reference voltage to each one of the current sources  114 . In some embodiments, the test point TP 5  reference voltage is approximately 0.49 Volts in order to provide 98 milliamps to each one of the current sources  114  (i.e., 98 milliamps to each set of six LEDs and 49 milliamps to each string of three LEDs). FIG. 12 illustrates one embodiment of the voltage reference module  104 . Two resistors R 18  (e.g., 1.5 kilo-ohms) and R 19  (e.g., 1 kilo-ohm) can form a voltage divider circuit that provides the test point TP 5  reference voltage. A voltage Vcc can be provided to a resistor R 17  (e.g., 3.3 kilo-ohms) and to a diode U 6  (e.g., a Model No. LM4041 zenar diode) for an output of 1.225 Volts (at test point TP 4 ). A transistor Q 5  (e.g., a Model No. ZVN3306 N-FET transistor manufactured by Zetex) can act as a switch to either provide 0.49 Volts (all the LEDs  12  are ON) or zero volts (all the LEDs are OFF) to test point TP 5 . A capacitor C 7  (e.g., 0.05 microfarads) is a filtering and decoupling capacitor that can be connected to the drain of the transistor Q 5 .  
     [0050] As shown in FIG. 13, the power control module  112  can include three transistors Q 1 , Q 3  and Q 4 . The transistor Q 1  can be a Model No. ZXMP3A13 P-FET transistor manufactured by Zetex. The transistors Q 3  and Q 4  can be Model No. ZVN3306 N-FET transistors manufactured by Zetex. The power control module  112  can include a first tactile switch SW 1  (e.g., a Model No. TL3301EF260QG or TL3301SPF260QG tactile switch manufactured by E-Switch). In one embodiment, a user can push the switch SW 1  so that eight standard AA-sized batteries provide a battery voltage VBatt of 12 Volts to the control circuit  100 . When a user presses the switch SW 1 , the gate of transistor Q 1  is grounded and power can flow through the transistor Q 1  (i.e., the transistor Q 1  is turned ON). Thus, when a user presses the switch SW 1 , power from the batteries VBatt (or power from any other suitable power source) can flow through the transistor Q 1  to the LEDs  12  via connection I. Power from the batteries VBatt can also flow through diode D 1  (e.g., a Model No. CMDSH-3 Super Mini Schottky diode manufactured by Zetex) to provide a voltage Vcc at test point TP 1 . The diode D 1  can provide reverse voltage protection from the batteries. The transistor Q 3  can invert the signal from the transistor Q 1  and can provide the inverted signal to the transistor Q 4 . The transistor Q 4  can invert the signal again to generate a START signal (on the connection H). In some embodiments, once the transistors Q 1 , Q 3  and Q 4  are ON, the voltage Vcc can be 12 Volts. The power control module  112  can include resistors R 1  (e.g., 10 kilo-ohms) and R 2  (e.g., 21.5 kilo-ohms) connected between the battery voltage VBatt, the switch SW 1 , and the transistor Q 1 . The power control module  112  can also include a capacitor C 6  (e.g., 0.05 microfarads) connected between the source and the gate of transistor Q 1 . In addition, the power control module  112  can include resistors R 3  (e.g., 21.5 kiloohms) and R 4  (e.g., 10 kilo-ohms) connected between the voltage Vcc and the drains of transistors Q 3  and Q 4 , respectively.  
     [0051]FIG. 14 illustrates one embodiment of the power-on reset module  110 . The power-on reset module  110  can include a counter  122  (e.g., a Model No. CD4020 binary counter integrated circuit manufactured by Texas Instruments). The power-on reset module  110  can also include two flip-flops  124  and  126  (e.g., a Model No. CD4013 dual D-type flip-flop integrated circuit manufactured by Texas Instruments) connected to the counter  122 . When the voltage Vcc is provided to the power-on reset module  110  after a user pushes the switch SW 1 , the counter  122  and the flip-flops  124  and  126  can be reset. When the voltage Vcc is provided to the power-on reset module  110 , a pin Q 14  of the counter  122  is initially at a zero state. The pin Q 14  of the counter  122  can be connected to an inverter  130  (e.g., a Model No. CD4011 NAND gate manufactured by Texas Instruments). When the pin Q 14  of the counter  122  provides a zero signal to the inverter  130 , the output of the inverter  130  is a high signal, which turns a transistor Q 2  ON (e.g., a Model No. ZVN3306 N-FET transistor manufactured by Zetex). The transistor Q 2  of the power-on reset module  110  can be connected to the transistor Q 1  of the power control module  112  (via the connection G). When the transistor Q 2  is ON, the gate of the transistor Q Iis grounded and the transistor Q 1  is ON.  
     [0052] The power-on reset module  110  can also include a 555 timer  132  (e.g., a Model No. ICM7555 general purpose 555 timer integrated circuit manufactured by Maxim and operating at a frequency of 45.8 Hz). Once a user turns the system ON by pressing the switch SW 1 , the 555 timer  132  can provide square waves or clock pulses to the counter  122  and to test point TP 2 . As the 555 timer  132  provides clock pulses, the counter  122  counts from pin Q 1  to pin Q 13 , during which approximately 88 seconds can elapse. When pin Q 13  goes to a high signal after 88 seconds, a clocking signal is provided to flip-flop  126 , which then provides a DRIVE LED zero signal on pin  12  and a DRIVE LED high signal on pin  13  of the flip-flop  126 . The DRIVE LED zero signal on pin  12  is provided to the transistor Q 5  of the voltage reference module  104  (via the connection F) in order to turn the transistor Q 5  OFF. When the transistor Q 5  is OFF, the reference voltage at test point TP 5  is zero and the LEDs  12  are OFF. The 555 timer  132  can continue to provide clock pulses until 88 more seconds (or any other suitable cooling-down period) have passed and pin Q 14  of the counter  4020  provides a high signal. The high signal can be provided from pin Q 14  of the counter  4020  to the inverter  130 . The inverter  130  can provide a zero signal to turn OFF the transistor Q 2 , which also turns OFF the transistor Q 1  of the power control module  112  (via the connection G) and turns OFF all power to the control circuit  100  (i.e., voltage Vcc is zero). In one embodiment, after the LEDs  12  are ON for a treatment session of 88 seconds, the LEDs are OFF for a cooling-down period of 88 seconds, and then all power is turned OFF to the control circuit  100 .  
     [0053] The power-on reset module  110  can include a tactile switch SW 2  (e.g., a Model No. TL3301EF260QG or TL3301SPF260QG tactile switch manufactured by E-Switch) that can be used as a STOP button. For example, if a user decides that he wants to turn the LEDs  12  OFF before the treatment session of 88 seconds has elapsed, the user can press the switch SW 2 . The switch SW 2  is connected to the flip-flop  124  which is connected to the flip-flop  126 . When the user presses the switch SW 2 , the flip-flop  126  provides a DRIVE LED zero signal on pin  12  which turns OFF the transistor Q 5  of the voltage reference module  104 . When the transistor Q 5  is OFF, the reference voltage at test point TP 5  is zero and the LEDs  12  are OFF.  
     [0054] The power-on reset module  110  can also include an AND gate  133 , the output of which is connected to the counter  122 . A capacitor C 1  (e.g., 1 microfarads), a diode D 2  (e.g., a Model No. ZHCS400TA diode), and a resistor R 5  (e.g., 10 kilo-ohms) can be connected to one input of the AND gate  133 . The other input of the AND gate  133  can be connected to ground. In addition, the power-on reset module  110  can include a capacitor C 2  (e.g., 0.12 microfarads) connected to pins  2  and  6  of the 555 timer  132 ; a resistor R 6  (e.g., 130 kilo-ohms) connected between pins  2  and  6  of the 555 timer  132  and a pin  10  of the counter  122 ; and a resistor R 7  (e.g., 1 kilo-ohm) connected between the switch SW 2  and a pin  6  of the flip-flop  124 .  
     [0055] In some embodiments, as shown in FIG. 15, the control circuit  100  can include a temperature sensing module  108  that can be used to prevent the LEDs  12  from being turned ON if the heat emitted by the LEDs  12  has not been adequately dissipated. The temperature sensing module  108  can include a temperature sensor  134  (e.g., a Model No. TC620CVOA dual trip point temperature sensor integrated circuit manufactured by MicroChip). The temperature sensor  134  can have a low set point or first threshold temperature (e.g., 45.8 degrees C.) determined by resistor R 9  (e.g., 130 kilo-ohms) and a high set point or a second threshold temperature (e.g., 53.8 degrees C.) determined by resistor R 8  (e.g., 137 kilo-ohms). If the sensed temperature is greater than the high set point, the heat sink  32  and/or the LEDs  12  are too hot and, if the LEDs  12  are ON, the LEDs  12  can be turned OFF immediately. A pin  6  of the temperature sensor  134  is connected (via the connection B) to a transistor Q 7  in the voltage reference module  104  (via the connection B). The transistor Q 7  turns OFF the LEDs  12  when the sensed temperature exceeds the high set point (i.e., the reference voltage at test point TP 5  becomes zero).  
     [0056] If the sensed temperature is greater than the low set point, but less than the high set point, the heat sink has not dissipated enough heat and the cooling-down period of the LEDs  12  can be extended. A pin  7  of the temperature sensor  134  can provide a high signal when the sensed temperature is greater than the low set point, but less than the high set point. The high signal can turn a transistor Q 6  ON and can provide a zero signal to one input of an AND gate  136 . A resistor R 10  (e.g., 10 kilo-ohms) can be connected between the drain of the transistor Q 6  and the voltage Vcc. A second input of the AND gate  136  can be connected to the pin  12  of the flip-flop  126  (via the connection B). The output signal of the AND gate  136  can be provided to a first inverter  138 , which can provide an output signal to a second inverter  140 . The second inverter  140  can be connected (via the connection J) to the 555 timer  132  of the power-on reset module  110 . If the signal provided on the pin  12  of the flip-flop  126  indicates that the control circuit  100  has already turned the LEDs  12  ON for 88 seconds and the LEDs  12  are now OFF, but the sensed temperature is too high, the cooling-down period of the LEDs can be extended. The cooling-down period of the LEDs can be extended until the sensed temperature falls below the low set point. Once the sensed temperature falls below the low set point, a reset on the 555 timer  132  can be removed to allow the 555 timer  132  to finish providing clock pulses for an 88 second time period.  
     [0057]FIG. 16 illustrates one embodiment of the battery voltage sensing module  106 . The battery voltage sensing module  106  can include a comparator circuit  142  that can determine whether the battery voltage is high enough to operate the control circuit  100  and the LEDs  12 . The comparator circuit  142  can include a comparator  144  (e.g., a Model No. TLC393 dual comparator manufactured by Texas Instruments) and resistors R 11  (e.g., 137 kilo-ohms), R 12  (e.g., 19.1 kilo-ohms), and R 13  (e.g., 301 kilo-ohms). A first input to the comparator  144  can be connected (via the connection D) to the reference voltage Vref (which can be 1.225 Volts) in the voltage reference module  104 . A second input to the comparator  144  can be connected between resistors R 11  and R 12 . If the comparator  144  determines that the voltage between resistors R 11  and R 12  is less than the reference voltage Vref, the output of the comparator  144  is a zero or low signal (LOW BATT) at test point TP 7 . A resistor R 14  (e.g., 21.5 kilo-ohms) can be connected between the voltage Vcc and the output of the comparator  144 . The output of the comparator  144  is also connected (via the connection L) to the first input of an AND gate  145  in the temperature sensing module  108 . The second input of the AND gate  145  in the temperature sensing module  108  is connected (via the connection E) to the pin  12  of the flip-flop  126  of the power-on reset module  110  (which provides a DRIVE LED signal) and to the gate of the transistor Q 5  of the voltage reference module  104 . If the output of the comparator  144  is the LOW BATT signal, the temperature sensing module  108  (through the AND gate  145  and the inverters  138  and  140 ) can prevent the 555 timer  132  from restarting by holding the 555 timer  132  in a reset state. In some embodiments, when the 555 timer  132  cannot be restarted, the LEDs  12  cannot be turned ON when a user presses the START button.  
     [0058] The battery voltage sensing module  106  can also include a first diode D 3  that can indicate to a user that the battery voltage is too low to operate the LEDs  12 . The diode D 3  can be connected to the comparator circuit  142  by an AND gate  146  and a comparator  148  (e.g., a Model TLC393 dual comparator manufactured by Texas Instruments). The inputs of the AND gate  146  can be connected to the output of the comparator  144  and to the drain of the transistor Q 4  of the power control module  112  (via connection H). The inputs of the comparator  148  can be connected to the output of the AND gate  146  and the reference voltage Vref of the voltage reference module  104  (via connection C). The drain of the transistor Q 4  of the power control module  112  can provide a START signal when a user presses the START button. Accordingly, when a user presses the START button and the comparator circuit  142  is providing the LOW BATT signal, the diode D 3  lights up to indicate to the user that the LEDs will not turn ON due to the voltage of the batteries or the power source being too low.  
     [0059] The battery voltage sensing module  106  can include a second diode D 4  that indicates to a user that the LEDs  12  will not turn ON during a cooling-down period. In some embodiments, after the LEDs  12  have been lit for 88 seconds, the cooling-down period can last another 88 seconds. The diode D 4  can be connected to a resistor R 16  (e.g., 390 Ohms) and an OR gate  150 . The inputs of the OR gate  150  can be connected to the output of the comparator circuit  142  and to the flip-flop  126  of the power-on reset module  110  (via the connection K). Accordingly, when the comparator circuit  142  is providing the LOW BATT signal and the flip-flop  126  is providing a low or zero DRIVE LED signal, the diode D 4  lights up to indicate to a user that the LEDs will not turn ON during the cooling-down period.  
     [0060] In some embodiments, the control circuit  100  can include one or more microprocessors in addition to or instead of the integrated circuits and individual electrical components described above with respect to FIGS.  10 - 16 . A microprocessor can be programmed to perform any of the functions described above with respect to FIGS.  10 - 16  or any additional functions that are desired.  
     [0061] Rather than a cooling-down period having a fixed duration, in some embodiments, the control circuit  100  can increase the cooling-down period if not enough heat has been dissipated from the LEDs  12  or decrease the cooling-down period if enough heat has already been dissipated from the LEDs  12 . The control circuit  100  can continually or intermittently monitor the temperature sensor  134  to determine when the temperature of the LEDs  12  and/or at least a portion of the circuit board  36  falls below a threshold temperature. In other embodiments, the control circuit  100  can be programmed to increase the cooling-down period after a certain number of treatment sessions and/or increase the cooling-down period after each consecutive treatment session. For example, after four 88 second treatment sessions, the control circuit  100  could extend the cooling-down period after the fourth treatment session to 100 seconds and the cooling-down period after the fifth treatment session to 120 seconds or greater. In some embodiments, the control circuit  100  includes a microprocessor programmed to increase or decrease the cooling-down period as described above.  
     [0062] According to the method of the invention, the hand-held device  10  can be positioned adjacent to the patient in a manner that allows the patient to absorb LED radiation. As one example, the hand-held device  10  can be positioned adjacent to the patient&#39;s leg. Once the hand-held device  10  is positioned in a manner that allows the patient to absorb LED radiation, the patient can be irradiated with LED radiation for treatment session having a predetermined time period, such as 88 seconds. In some embodiments, the patient is irradiated for 88 seconds at a power density of approximately 4 to 8 Joules per centimeter squared. However, the patient may be irradiated for shorter or longer periods of time at lesser or greater power densities. In some embodiments, the patient is irradiated for two or more treatment sessions of about 88 seconds each. A cooling-down period of about 88 seconds can be provided between treatment sessions, during which the LEDs are prevented from emitting radiation.  
     [0063] Although several embodiments of the present invention have been shown and described, alternate embodiments will be apparent to those skilled in the art and are within the intended scope of the present invention. Therefore, the invention is to be limited only by the following claims.