Therapeutic Light Source and Method
A therapeutic light source, for example for photodynamic therapy (PDT), comprises an air-cooled array of LED's (Lx,y), the air being vented in the vicinity of the array. The array may be mounted at the distal end of a hand piece suitable for invasive therapy. The LED's may be coupled to a light guide (W, L). The emission spectra of the LED's may be substantially limited to the range 550 to 660 nm, and preferably to one of the ranges 590 to 640 nm, 560 to 644 nm, 650 to 660 nm, and 550 to 570 nm. The therapeutic light source may comprise a non-planar array of light-emitting diodes L conforming with the shape of an external area to be treated or diagnosed. The therapeutic light source may comprise a non-planar array of independently switchable red and blue light-emitting diodes LR, LB, mounted on a flexible backing.
This application is a divisional of U.S. patent application Ser. No. 10/625,701, filed Jul. 24, 2003, which is a continuation of U.S. patent application Ser. No. 09/815,348, filed Mar. 23, 2001, each of which is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to a non-coherent light source for use in therapy such as photodynamic therapy (PDT), particularly using light emitting diodes (LED's).
2. Related Art
Photodynamic therapy involves the administration of a photosensitising drug to an affected area, and its subsequent irradiation with light—see for example The Physics of Photodynamic Therapy by B C Wilson and M S Patterson, Physics in Medicine & Biology 31 (1986) April No. 4, London GB.
The document GB 2,212,010 discloses a therapeutic light source which uses an array of discrete LED's as an alternative to lasers or laser diodes. The output of the LED's is focussed so as to provide the necessary intensity.
The document WO 94/15666 discloses a therapeutic light source specifically for PDT, with an integrated array of LED's mounted on the distal end of a hand piece. The LED's are overdriven to give the necessary intensity, and cooled by the flow of water around a closed loop passing along the hand piece. The document U.S. Pat. No. 5,728,090 discloses a somewhat similar device with various different types of head containing integrated LED matrices. These devices require complicated liquid cooling circuits which would add to the cost of the device and add to the bulk of the hand piece, which is disadvantageous for invasive use.
The document U.S. Pat. No. 5,728,090 mentions that the wavelength of the LED's is between 300 nm and 1300 nm and is selected based upon the particular photosensitive dye used during PDT. However, the wavelengths of LED's capable of providing the necessary intensity for PDT cannot freely be chosen within that range.
SUMMARY OF THE INVENTIONAccording to one aspect of the present invention, there is provided a light source for therapy and/or diagnosis, comprising a non-planar array of light-emitting diodes conforming with the shape of an external area to be treated or diagnosed.
According to another aspect of the present invention, there is provided a light source for therapy and/or diagnosis, comprising a first array of light-emitting diodes and a second array of light emitting diodes movably connected thereto.
According to another aspect of the present invention, there is provided a light source for therapy and/or diagnosis, comprising an array of light-emitting diodes mounted on the curved inner surface of a housing arranged to cover at least part of the length of a patient.
According to another aspect of the present invention, there is provided a light source for therapy or diagnosis of a patient, comprising an array of light-emitting diodes arranged within a housing, and an aperture allowing a part of the patient's body to be inserted into the housing, the array being arranged to direct light onto the part of the patient's body when inserted into the housing.
According to another aspect of the present invention, there is provided a light source for therapy or diagnosis of a patient, comprising an array of light-emitting diodes arranged within a sleeve so as to direct light onto part of an arm and/or hand of a patient when inserted into the sleeve.
According to another aspect of the present invention, there is provided a light source for therapy or diagnosis of a patient, comprising an intraluminal probe carrying on the surface thereof an array of discrete light-emitting diodes.
According to another aspect of the present invention, there is provided a therapeutic light source comprising an air-cooled array of LED's, the air being vented in the vicinity of the array. In one embodiment, the array is mounted at the distal end of a hand piece suitable for invasive therapy.
According to another aspect of the present invention, there is provided a therapeutic light source comprising an array of LED's coupled to a light guide for delivering the light to the area to be treated. Preferably, the LED's are directly coupled without intervening optical devices.
According to another aspect of the present invention, there is provided a therapeutic light source comprising an array of LED's with emission spectra substantially limited to the range 550 to 660 nm, and preferably to one of the ranges 590 to 640 nm, 560 to 644 nm, 650 to 660 nm, and 550 to 570 nm.
According to another aspect of the present invention, there is provided a therapeutic light source comprising an array of LED's with peak emission spectra of approximately 430 nm, 470 nm, 505 nm or 525 nm.
BRIEF DESCRIPTION OF THE DRAWINGS/FIGURESSpecific embodiments of the present invention will now be described with reference to the accompanying drawings, in which:
In a therapeutic light source in the first embodiment, as illustrated in FIGS. 1 to 5, light is emitted from a parallel-series matrix of LED's L connected through a current-limiting resistor R to a source of a voltage +V. The LED matrix is mounted on a heatsink array H parallel to and spaced apart from a fan array F by support rods R. Air is blown by the fan array F onto the back of the heatsink array H.
As shown in more detail in
The LED's L are arranged so as to produce a substantially uniform illumination of.+−0.10% or less across a treatment field by selecting the beam divergence and spacing of the LED's L so that their individual beams overlap without causing substantial peaks or troughs in intensity. In the example shown in
In one specific example, a 15 cm diameter array of 288 ‘Super flux’ LED's was used to produce a total light output of 8 W at 45 mW/cm.sup.2 in the treatment field. The LED's were driven at a higher current load than their specification while being cooled by forced air convection from the fans F. In the specific example, the current was limited to 90 mA per column of diodes, but may be increased to 120 mA or more if increased light output is needed. The number of diodes in series, in each column, is selected so that the total forward operating voltage is as close as possible to, but less than, the power supply output voltage, in this case 48 V. This arrangement avoids wasteful in-circuit heating and maximizes the operating efficiency of the electrical system.
A method of treatment for oncological and non-oncological skin diseases such as cases of actinic/solar keratoses, Bowen's disease, superficial basal cell carcinoma, squamous cell carcinoma, intraepithelial carcinoma, mycosis fungoides, T-cell lymphoma, acne and seborrhoea, eczema, psoriasis, nevus sebaceous, gastrointestinal conditions (e.g. Barratt's oesophagus and colorectal carcinomas), gynaecological disorders (e.g. VIN, CIN and excessive uterine bleeding), oral cancers (e.g. pre-malignant or dyplastic lesions and squamous cell carcinomas), viral infections such as herpes simplex, molluscum contagiosum, and warts (recalcitrant, verruca vulgaris or verruca plantaris), alopecia greata, or hirsutism, using the first embodiment, will now be described. A cream or solution containing a photosensitising drug such as 5-ALA is applied topically under medical supervision to the affected area of the skin of the patient, or administered intravenously or orally. In another method of application for large areas, the patient may be immersed in a bath of solution. The affected area may then be covered for a period of 3 to 6 hours, or up to 24 hours if the treatment is to be continued the next day, to prevent removal of the drug and carrier, or activation by sunlight. The area is then uncovered and exposed to light from the lamp according to the first embodiment for a period of 15 to 30 minutes. The treatment may then be repeated as necessary, for a total of 1 to 3 treatments. This method is particularly suitable for the treatment of patients with very large lesions or multiple lesions extending over a large area.
In a method of treatment using the device of the first embodiment, the LED array is positioned approximately parallel to an external affected area of a patient to be treated, with a separation sufficient to achieve the uniform illumination as shown in
The lamp may also be used for fluorescence detection (photodiagnosis).
The first embodiment may be modified in a second embodiment, as shown in
The second embodiment may be modified in a third embodiment, as shown in
The third embodiment may be modified in a fourth embodiment, as shown in
A fifth embodiment, as shown in
The selection of appropriate discrete LED's for PDT using any of the first to fourth embodiments will now be described, grouped according to die material.
A first suitable type of LED is based on aluminium indium gallium phosphide/gallium phosphide (AlInGaP/GaP) of transparent substrate (TS) or absorbing substrate (AS) type. The output wavelengths are in the range 590 to 640 nm with peak emission wavelengths of 590, 596, 605, 615, 626, 630 and 640 nm. Commercially available examples are the ‘SunPower’™ or ‘Precision Optical Power’™ series from Hewlett Packard Company, designed for use in the automotive industry, for commercial outdoor advertising and traffic management. Suitable LED's are those packaged as: SMT (surface mount technology) e.g. HSMA, HSMB, HSMC, HSML series and preferably HSMB HR00 R1T20 or HSMB HA00R1T2H; Axial e.g. HLMA or HLMT series; T1 e.g. HLMP series, preferably HLMP NG05, HLMP NG07, HLMP J105; T13/4 e.g. HLMP series, preferably HLMP DG08, HLMP DG15, HLMP GG08, HLMP DD16; Superflux™ e.g. HPWA or HPWT series, preferably HPWA (MH/DH/ML/DL) 00 00000, HPWT (RD/MD/DD/BD/RH/MH/DH/BH/RL/ML/DL/BL) 00 00000, most preferably HPWT (DD/DH/DL/MH/ML/MD) 00 00000; SnapLED™ e.g. HPWT, IHPWS, HPWL series, preferably BPWT (SH/PH/SL/PL) 00, HPWT (TH/FH/TL/FL) 00 or HPWS (TH/FH/TL/FL) 00. Suitable products from other manufacturers include: of SMT type, Advanced Products Inc. (API) part no. HCL4205AO; of T1 type, American Bright Optoelectronics (ABO) part no. BL BJ3331E or BL BJ2331E; of Superflux type, ABO part no.'s BL F2J23, BL F2J33 and BL F1F33.
A second suitable type of LED is the aluminium indium gallium phosphide/gallium arsenic (AlInGaP/GaAs) type, with emission wavelengths in the range 560 to 644 nm and peak emission wavelengths of 562 nm, 574 nm, 590 nm, 612 nm, 620 nm, 623 nm and 644 nm. Examples commercially available from Toshiba in T1 package are the TLRH, TLRE, TLSH, TLOH or TLYH series, preferably TLRH 262, TLRH 160, TLRE 160, TLSH 1100, TLOH 1100, TLYH 1100 or S4F4 2Q1; or in T13/4 package are the TLRH or TLSH series, preferably TLRH 180P or TLSH 180P. Another example is Kingbright L934SURC-E.
A third suitable type of LED is aluminium gallium arsenic type (AlGaAs), with emission wavelengths in the range 650 to 660 nm. Examples in T1 package include the Toshiba TLRA series, preferably TLRA 290P or TLRA 293P, and Kingbright L934 SRCG, L934 SRCH, and L934 SRCJ and in T13/4 package include Kingbright L53 SRCE.
A fourth suitable type of LED is gallium phosphide (GaP) type, with emission wavelengths in the range 550 to 570 nm.
A fifth suitable type of LED is indium gallium nitride (InGaN). In the type with an emission wavelength of 525 nm, commercially available examples include: in SMT package, API's HCL 1513AG; and in T1 package, Farnell's #942 467, Radio Spare's #228 1879 and #249 8752, API's HB3h 443AG and Plus Opto's NSPG500S. In the type with emission wavelengths of 470 and 505 nm and T1 package type, examples are Farnell's #142 773, Radio Spare's #235 9900 and American Bright Optoelectronics Inc.'s BL BH3PW1.
A sixth suitable type of LED is gallium nitride/silicon (GaN/Si), with an emission wavelength of 430 nm. One commercial example is Siemens LB3336 (also known as RS #284 1386).
Each of the above LED types is selected to have an emission spectrum substantially coincident with the absorption spectrum of one or more of the following common photosensitizers given below in Table 1, and therefore embodiments having such LED's are suitable for PDT. For example,
The discrete LED array may comprise more than one different type of LED, each with different emission spectra, selected to match different absorption bands of the selected photosensitizer. Each type of LED may be switched independently. The penetration depth (i.e. the depth at which the intensity has been attenuated to e.sup.-1) may also be varied by switching on only one type of LED in the array so as to select a suitable emission band, since the penetration depth is a function of the wavelength.
The LED array may be composed of individually switchable spatially distinct segments of LED's. Selected segments may be switched on so as to treat a selected area of the patient within the overall area of the matrix array.
The lamp may include an electro-optical detector arranged to monitor the light dose delivered and to switch off the light emission when a target dose is reached. Alternatively, or additionally, the detector is arranged to monitor the instantaneous light intensity and to vary the electrical power supplied to the tubes so as to maintain the intensity within predetermined limits, and/or to switch off the light emission if a maximum limit is exceeded.
Various different arrangements of LED array suitable for treatment of different areas of a patient will now be described. The LED's are discrete LED's as described above. Except where stated otherwise, the LED's may be fan-cooled using integrated fans.
In tests performed by the inventor, the efficacy of PDT using red (approximately 630 nm) emission from LED's was established in in-vivo comparative studies using a sub-cutaneous mammary tumour regrowth delay assay. Using radiobiological end-points, it was shown that the solid-state prototype efficacies were comparable to that of expensive conventional lasers for PDT (i.e. no significant difference, p=0.21). These results were confirmed in further clinical studies in the treatment of Bowen's disease and basal cell carcinomas where comparative complete response rates were achieved as compared to laser PDT.
The blue LED's have an emission spectrum substantially (for example fill width half maximum bandwidth) in the range 370 to 450 nm, and preferably 400 to 430 nm. This range is particularly suitable for the treatment of pre-cancerous conditions, in particular actinic keratoses.
The red LED's have an emission spectrum substantially (for example full width half maximum bandwidth) in the range 620 to 700 nm. This range is particularly suitable for the treatment of non-melanoma, such as basal cell or squamous cell carcinoma, or mycosis fungoides.
Claims
1. A light source for therapy and/or diagnosis, comprising a non-planar array of discrete light-emitting diodes mounted on a head portion for attachment to the head of a patient such that light is emitted onto the face of the patient, and one or more fans for cooling the array of discrete light-emitting diodes.
2. A method of treatment of the face and/or scalp, comprising illuminating respectively the face and/or scalp of a patient with light from a light source comprising a first rigid array of light-emitting diodes, a second rigid array of light emitting diodes movably connected to a first edge of the first array, and a third rigid array of light-emitting diodes movably connected to a second edge of the first array.
3. A light source for therapy and/or diagnosis, comprising a support for supporting the patient and an array of light-emitting diodes mounted on a curved inner surface of a rigid cover arranged to cover at least part of the length of a patient when supported by the support.
4. A light source as claimed in claim 3, wherein said support includes a further array of light-emitting diodes.
5. A light source as claimed in claim 4, wherein said further array comprises a plurality of sections which are independently switchable.
6. A light source as claimed in any one of claims 3 to 5, wherein said further array is planar.
7. A light source for therapy or diagnosis, comprising an array of light emitting diodes coupled to a waveguide which tapers away from the diodes so as to concentrate light emitted by the diodes.
8. A light source according to claim 7, including a parallel-sided light guide coupled to the waveguide so that the light emitted by the light-emitting diodes is concentrated into the parallel-sided light guide.
9. A light source according to claim 8, wherein the parallel-sided light guide comprises one or more optical fibres and/or liquid light guides.
10. A light source according to claim 7 or 8, wherein the waveguide is frusto-conical.
11. A light source according to claim 10, wherein the waveguide is of acrylic or glass.
12. A light source according to claim 7 or 8, including an array of individual heatsinks mounted on the light-emitting diodes.
13. A therapeutic light source, comprising an array of light-emitting diodes arranged so that light from the light-emitting diodes is incident directly in the treatment field with an output intensity of at least 10 mW/cm2 and a spatial intensity fluctuation of 6% or less, and means for cooling the diodes by forced air convection.
14. A therapeutic light source, comprising an array of discretely mounted light-emitting diodes arranged so that light from the light-emitting diodes is incident directly in the treatment field with an output intensity of at least 10 mW/cm2 and a spatial intensity fluctuation of 10% or less, and means for cooling the diodes by forced air convection.
15. A light source as claimed in claim 14, wherein the light-emitting diodes are electrically connected in a parallel-series matrix.
16. A light source as claimed in claim 14, wherein the diodes are thermally coupled to one or more heatsinks.
17. A light source as claimed in claim 14, wherein the diodes are thermally coupled to an array of individual heatsinks.
18. A light source as claimed in claim 14, wherein the light-emitting diodes and the heatsinks are mounted on opposite sides of a support plate.
19. A light source as claimed in claim 18, wherein the support plate is perforated to allow air to flow around the heatsinks and light-emitting diodes.
20. A therapeutic light source, comprising an array of discretely mounted light-emitting diodes thermally coupled to an array of individual heatsinks and arranged so that light from the light-emitting diodes is incident in a treatment field, and means for cooling the diodes by forced air convection.
21. A light source as claimed in claim 20, wherein the treatment field has an extent approximately equal to that of the array of diodes.
22. A light source as claimed in claim 20, wherein the light is incident directly in the treatment field.
23. A light source as claimed in claim 20, wherein the spatial intensity fluctuation of the light in the treatment field is 10% or less.
24. A light source as claimed in claim 20, wherein the spatial intensity fluctuation of the light in the treatment field is 6% or less.
25. A light source as claimed in claim 20, wherein the light-emitting diodes and the heatsinks are mounted on a support plate.
26. A light source as claimed in claim 25, wherein the light-emitting diodes and the heatsinks are mounted on opposite sides of the support plate.
27. A light source as claimed in claim 26, wherein the support plate is perforated to allow air to flow around the heatsinks and light emitting diodes.
28. A light source as claimed in claim 25, wherein the support plate is perforated to allow air to flow around the heatsinks and light-emitting diodes.
29. A light source as claimed in claim 20, wherein light from the light-emitting diodes is not concentrated by any optical system.
30. A light source as claimed in claim 20, wherein the light emitting diodes have emission wavelengths substantially in a range of 370 to 450 nm.
31. A light source as claimed in claim 30, wherein the light emitting diodes have emission wavelengths substantially in a range of 400 to 430 nm.
32. A light source as claimed in claim 20, wherein the light emitting diodes have emission wavelengths substantially in a range of 550 to 660 nm.
33. A light source as claimed in claim 32, wherein the light emitting diodes have emission wavelengths substantially in a range of 590 to 640 nm.
34. Use of a light source as claimed in claim 20, for cosmetic treatment of a patient.
35. Use as claimed in claim 34, wherein the treatment comprises skin rejuvenation.
36. Use as claimed in claim 34, wherein the treatment comprises wrinkle removal.
37. Use as claimed in claim 34, wherein the treatment comprises biostimulation.
Type: Application
Filed: Jun 12, 2007
Publication Date: Oct 4, 2007
Inventor: Colin WHITEHURST (Cheshire)
Application Number: 11/761,928
International Classification: A61N 5/06 (20060101);