Surgery – Instruments – Light application
Reexamination Certificate
1999-04-30
2001-11-13
Gibson, Roy (Department: 3739)
Surgery
Instruments
Light application
C606S015000, C607S089000, C362S558000
Reexamination Certificate
active
06315775
ABSTRACT:
TECHNICAL DOMAIN
The current invention relates to an appliance for light diffusion designed specifically for the irradiation of biological tissues during photodynamic therapy. This appliance is comprised of a light conductor, in particular a fiber optic with a section at its tip exposed to the core, with the section surrounded by at least one layer of diffusing substance with the ability to diffuse the light circulating in said light conductor.
PREVIOUS TECHNIQUE
In the photodynamic treatment of cancerous surface lesions or other pathological diseases in human body organs, the technique currently being used consists of intravenously injecting a sensitizer which becomes localized particularly in neoplastic tissues. The part of the diseased tissue containing the photosensitizer is then irradiated with a light, the wavelength of which is decided by the photosensitizer injected. This light activates the photosensitizer and causes a chemical reaction which destroys the cells. This irradiation is implemented with the help of flexible diffusers guiding the light which generally originates from a laser source and they diffuse this light in the organ undergoing treatment in a controlled way. The intensity of the light emitted by the diffuser must be homogeneous over the entire surface to be treated in order to avoid problems linked with over- or under-exposure. Over-exposure caused by strong luminous power can cause damage to adjacent healthy tissues as well as local heating. Under-exposure can lead to a recurrence of the illness if specific cells are not killed by the treatment.
Several diffusers of this type are known, in particular the light diffuser described in American patent U.S. Pat. No. 5,536,265. This diffuser is comprised of a fiber optic with a section at its tip exposed to the core, a first layer of a flexible transparent substance, a second layer of a material capable of diffusing light, all of this contained in a transparent tubular part which forms a protective casing.
On the one hand, this diffuser is of complex design. On the other hand, the fiber optic section at the tip, which can reach around 10 centimeters with a diameter of several hundred microns, is extremely difficult to center inside a tubular part because of the flexibility of these two elements. As a result, the second layer, which is made from a material with diffusing properties, is irregular around the exposed fiber core which forms the section at the tip. However, diffusing properties are linked, in particular, with the thickness of the diffusing matter surrounding the core.
In order to obtain a homogeneous diffusion of the light transmitted by the fiber optic, it is essential for the diffusing particles to be distributed in a homogeneous way and that the thickness of the diffusing layer remains constant.
DESCRIPTION OF THE INVENTION
The aim of the current invention is to eliminate these drawbacks of the previous method by providing a diffusing appliance which addresses this objective and which is of simplified design. For this purpose, the appliance according to the invention is characterized by the fact that the layer of light diffusing substance is comprised of a tubular manufactured part with walls of a consistent thickness to which the fiber tip section is attached.
In accordance with a more beneficial manufacturing process, this tubular part is made of a thermoformable material which incorporates diffusing particles that are able to diffuse light. These particles are distributed homogeneously throughout this thermoformable material.
Ideally it will include a layer of transparent material positioned between the external face of the tip section and the internal wall of the tubular part.
As a benefit the appliance can include at its distal extremity a mirror arranged to reflect light emanating from the fiber tip section into the fiber.
The tubular part is preferably manufactured by extrusion from a long tubular segment of thermoformable material containing diffusing particles and by cutting to size a section of predetermined length.
The tubular part with the diffusing properties will ideally form the external protective casing of the fiber optic section.
REFERENCES:
patent: 4733332 (1988-03-01), Yamashita et al.
patent: 5207669 (1993-05-01), Baker et al.
patent: 5431647 (1995-07-01), Purcell et al.
patent: 5536265 (1996-07-01), Van den Bergh
patent: WO 90 00914 A (1990-02-01), None
patent: WO 93 25155 A (1993-12-01), None
patent: WO 96 07451 A (1996-03-01), None
patent: WO 97 07735 A (1997-03-01), None
Thielen Patrick
Woodtli Alain
Gibson Roy
Medlight S.A.
Nixon & Vanderhye P.C.
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