Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Light application
Patent
1994-08-24
1998-12-01
Nasser, Robert L.
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Light application
607 90, 250504R, A61N 500
Patent
active
058431438
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a light source which is an incoherent or non-laser light source for use primarily but not exclusively in medical applications.
Lasers have widespread uses in the treatment of the human or animal body, which uses may be of a therapeutic and/or cosmetic nature. For example, laser light can be used to kill cancer cells or for treatment of portwine stains and removal of tattoos. However, medical lasers tend to have many disadvantages. Firstly, some medical lasers for certain requirements can cost up to one hundred and forty thousand pounds or more and may require very bulky power supplies and/or bulky transformers in addition to involving complex or inconvenient cooling arrangements. Additionally, the power consumption by the laser may be very high and the laser itself may not be user friendly, for example, some lasers may require a one and a half hour warm-up time before they can be used in certain applications and may have a similar shut-off period. Often, the laser itself may be a far more sophisticated piece of equipment than is actually required for a particular task and therefore may be over suited to the task in hand. Some medical applications do not in fact require the criticality offered by a laser although other acceptable light sources do not seem to have been developed to be used instead of a laser in such applications.
Non-laser light sources have been developed for medical applications but such proposals have tended to be inefficient and generally unsuitable for the task in hand.
For example, a paper from the Journal of Photochemistry and Photobiology B: Biology 6 (1990) 143-148 on Photodynamic Therapy with Endogenous Protoporphyrin reports the use of a 500 watt filament light source for irradiation of cancerous cells. The light source was varied from 150 to 300 watts per square centimeter but spread over a very wasteful large bandwidth greater than 100 nm. The filtering tended to be inefficient and unsuitable giving rise to tissue damage from thermal effects.
Another proposal is discussed in the "Phototherapy of Human Cancers" in an article entitled Porphyrin Localisation and Treatment of Tumors, pages 693-708, 1984 Alan R. Liss, Inc. This article discusses the use of a filtered incandescent lamp having a 1000 watt filament source which is water cooled. The size of the apparatus itself is large and tends to be inefficient also entailing considerable risk of skin damage because of high flux density.
It is an object of at least some embodiments of the present invention to provide an incoherent or non-laser light source which at least alleviates one or more of the aforementioned, or other, disadvantages associated with lasers or which is more suited to the particular task in hand than a laser.
According to a first aspect of the present invention there is provided an incoherent or non-laser light source comprising a high intensity lamp, a bandpass filter and focusing means arranged to yield a light beam having an output intensity greater than 0.075 watts per square centimeter for a bandwidth in the range 0 to 30 nm and preferably in the range 0 to 25 nm.
Usually, the output intensity of said light source will be greater than 1 watt per square centimeter for a bandwidth usually in the range 20 to 25 nm.
Preferably, the light source is tunable over a range of at least 350 to 700 nm and usually over a range of 250 to 1100 nm.
Preferably, the output beam is focused sufficiently so that light can be delivered by way of an optical fibre means or bundle to its point of action and said beam may be focused down to a 6 mm or less diameter.
In one embodiment of the present invention, the light source may be arranged to yield a beam with an output intensity of 6 watts per square centimeter at a bandwidth of 20 to 25 nm. The lamp may be a metal halide lamp.
Alternatively, the lamp may be a high intensity high pressure xenon, short arc lamp or any lamp producing intense light over a continuous spectrum. It is envisaged that an extended light source such as a filament would not produce th
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Physics in Medicine and Biology, vol. 31, No. 4, Apr. 1986--Wilson et al: "The physics of photodynamic therary" see p. 334, paragraph 3 Light sources for PDT, see p. 335, table 2.
Cancer Research Campaign Technology Ltd.
Nasser Robert L.
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