Surgery – Instruments – Light application
Reexamination Certificate
2001-12-13
2003-08-19
Gibson, Roy D. (Department: 3739)
Surgery
Instruments
Light application
C606S011000, C606S018000
Reexamination Certificate
active
06607523
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus for tissue treatment, such as for hair removal and for photocoagulation of veins.
BACKGROUND OF THE INVENTION
It is known to utilise laser light for tissue treatment, such as cosmetic tissue treatment, such as dermal ablation, removal of hair, photocoagulation of veins, etc.
Hair removal may be effected by directing a laser beam at a hair follicle to destroy the hair follicle and its adjacent blood vessels by the heat produced by photothermolysis.
Furthermore, coagulation of veins may be effected by directing a laser beam at the veins to coagulate the blood in the veins.
During treatment of tissue, such as an epidermal layer, hair, veins, etc, it is essential not to damage underlying or surrounding tissue. Residual heat may cause untreated cells to char and become necrotic, whereby scars may be formed. Thus, it is desirable to apply laser power only to tissue to be treated and only for a short time, to minimise transmission of conducted heat to underlying and surrounding tissue.
To some extend this has been obtained by selective photothermolysis, i.e. laser light is utilised having a wavelength that is selectively absorbed by tissue to be treated and that is not absorbed by the surrounding and healthy tissue. The selective absorption of the laser light causes selective photothermolysis in the tissue to be treated.
SUMMARY OF THE INVENTION
Light of a wavelength that is absorbed in a hair follicle and its adjacent blood vessels will be scattered in all directions when propagating from a tissue surface down to the hair follicle to be destroyed by the heat produced by photothermolysis. Therefore, it is required to illuminate a rather large spot on the tissue surface above the hair follicle(s) to be destroyed in order to increase the probability of photons being scattered in direction of the hair follicle(s). Simultaneously, the power of the illuminating light beam must be sufficient for enough heat to be generated to destroy the hair follicle and its adjacent blood vessels.
In the art this has lead to bulky hair depilators with high power lasers producing a spot size of 10 mm or more.
Throughout the present description the term spot size means the diameter of the spot in question.
It is an object of the present invention to provide an apparatus for hair removal that is adapted to automatically and accurately destroy hair follicles without damaging surrounding tissue.
It is another object of the present invention to provide an apparatus for hair removal that is adapted to remove hair from a large area of a patient.
It is a further object of the present invention to provide an apparatus for hair removal, having a handpiece that can be moved around, i.e. traversed and rotated, freely by an operator, i.e. without exerting forces acting against the movement.
According to a first aspect of the invention, the above-mentioned and other objects are fulfilled by an apparatus for tissue treatment comprising a light emitter for emission of a first light beam, movable first deflecting means for deflection of the first light beam into a treating light beam, an output for emission of the treating light beam towards a target surface and illuminating a spot on the target surface, first moving means for moving the first deflecting means, and first deflecting control means for controlling the first moving means and being adapted to control the first moving means so that the treating light beam traverses a target surface area stepwise with steps that are greater than half the diameter of the spot.
According to a second aspect of the invention, a handpiece is also provided, comprising an input connector for connection of a first beam-outlet end of a first optical fibre to the handpiece and for alignment of the first optical fibre with an axis of the handpiece so that a first light beam emitted from the first beam-outlet end is transmitted substantially along to the axis, movable first deflecting means for deflection of the first light beam into a treating light beam, an output for emission of the treating light beam towards a target surface and illuminating a spot on the target surface, first moving means for moving the first deflecting means, and first deflecting control means for controlling the first moving means and being adapted to control the first moving means so that the treating light beam traverses a target surface area stepwise with steps that are greater than half the diameter of the spot.
When the handpiece is kept in a fixed position in relation to a target surface that is illuminated by the treating light beam changing of the position of the deflecting means causes the treating light beam to traverse or scan the target surface along a curve. An area may be traversed or scanned by the treating light beam, e.g. by letting the treating light beam traverse or scan a meander like curve substantially covering the area or, by traversing or scanning the area line by line. In the present context, the type, number and shape of curves traversed by the treating light beam in order to traverse a specific area is denoted the traversing pattern or the scan pattern. The area that is scanned or traversed by the treating light beam is denoted the scan area, the treatment area or the traversed area. The scanning may be performed stepwise as further explained below.
In the art, it has hiterto been recognised that efficiency of hair removal can be increased by increasing spot size and laser power. However, it has surprisingly been found by the present inventors that a smaller spot size and a low power laser can lead to effective hair removal so that an apparatus for hair removal that is not bulky and expensive is provided according to the present invention.
According to the present invention, an apparatus for tissue treatment illuminating a spot size ranging from 1 to 9 mm, preferably from 2 to 8 mm, more preferred from 2 to 6 mm, most preferred approximately 4 mm, is provided.
It is further preferred that the output power of the diode laser is less than 250 W, preferably less than 175 W, more preferably less than 125 W, most preferred approximately 80 W.
In order to distribute energy uniformly across tissue to be treated, it is preferred to scan the tissue along a curve in steps whereby the illuminated spot is allowed to stay in a specific treating position 40-100 ms, such as 60-100 ms, preferably approximately 80 ms, followed by movement of the spot to the next treating position within a few milliseconds. Preferably, the centre to centre distance between two succeeding spot positions is less than a spot diameter, such as between half a spot diameter and a diameter of the spot, preferably such as approximately half a spot diameter, most preferred such as two thirds a spot diameter, so as to provide for a controlled overlap of the spots resulting in an effective hair removal. The thus implied overlap ensures a uniform distribution of energy across the traversed tissue area, and thus a uniform removal of hairs. It is further preferred to scan the tissue area line by line scanned successively in the same directions having a spot overlap such as mentioned above.
However, the treating light beam traverses a line to be treated a first time and a second time stepwise with a step size being substantially greater than the diameter of the spot. The centre to centre distance between two succeeding treating spot positions may be thus be larger than a spot diameter, such as 1.5 times a spot diameter, preferably such as approx. four thirds a spot diameter, and still provide effective hair removal. The scanning may be performed so that the first traversing of the treating light beam illuminates a first sequence of spots and the second traversing of the treating light beam illuminates a second sequence of spots in the same line, the distance between the first illuminated spot in the first sequence and the first illuminated spot in the second sequence being substantially equal to half the size of the steps between succeeding illuminated spots in the firs
Asah Bjarne
Balle-Petersen Olav
Dolleris Casper
Asah Medico A/S
Birch & Stewart Kolasch & Birch, LLP
Gibson Roy D.
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