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Proceedings Paper

Comparison between reflectance spectra obtained with an integrating sphere and a fiber optic collection system
Author(s): Lill Tove Norvang Nilsen; Elisanne Janne Fiskerstrand; Karsten Koenig; B. Bakken; D. Grini; O. Standahl; Thomas E. Milner; Michael W. Berns; J. Stuart Nelson; Lars Othar Svaasand
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Paper Abstract

Visible reflectance spectra of human skin might serve as a valuable tool for determining blood volume and pigmentation. They can therefore be used to evaluate the response to various skin treatments such as, e.g., port-wine stain therapy. A fiber-optic system is preferable for clinical evaluation of the therapeutic response due to its higher flexibility. Diffuse reflectance spectra obtained using a fiber system are compared with the corresponding spectra from an integrating sphere system. The results show that the most accurate reflectance spectra are obtained using the integrating sphere set-up. The aperture should then be much larger than the optical penetration depth of the skin. The system will then collect all the reflected light from superficial and deeper layers, and this enables a qualitative comparison between the wavelengths. However, the size and localization of many dermal lesions limit its use. In these cases the fiber-optic system is preferable. Light with an optical penetration depth shorter than the distance between the excitation and collecting fibers is, however, favorized. Normal dermis has typically a penetration depth of 600 micrometers and 2000 micrometers for, respectively, green/yellow and red light. Consequently, the collection efficiency of a typical fiber-optic system with a distance of 100 - 200 micrometers between the emitting and collecting fibers, will be higher in the green/yellow than in the red part of the spectrum. It is, however, important to remember that the relevant parameter is the change in reflectance at each particular wavelength, rather than comparison between the wavelengths. When such a comparison is required, the spectra collected by the fiber-optic system can be calibrated. The more accurate integrating sphere system is maybe preferable in a research laboratory environment, whereas the more flexible fiber-optic system is the most applicable for use in the clinic.

Paper Details

Date Published: 10 January 1996
PDF: 10 pages
Proc. SPIE 2624, Laser-Tissue Interaction and Tissue Optics, (10 January 1996); doi: 10.1117/12.229549
Show Author Affiliations
Lill Tove Norvang Nilsen, Norwegian Institute of Technology and Univ. of California/Irvine (Norway)
Elisanne Janne Fiskerstrand, Univ. Hospital of Trondheim (Norway)
Karsten Koenig, Institute of Molecular Biotechnology (Germany)
B. Bakken, Norwegian Institute of Technology (Norway)
D. Grini, Norwegian Institute of Technology (Norway)
O. Standahl, Norwegian Institute of Technology (Norway)
Thomas E. Milner, Univ. of California/Irvine (United States)
Michael W. Berns, Univ. of California/Irvine (United States)
J. Stuart Nelson, Univ. of California/Irvine (United States)
Lars Othar Svaasand, Norwegian Institute of Technology and Univ. of California/Irvine (Norway)

Published in SPIE Proceedings Vol. 2624:
Laser-Tissue Interaction and Tissue Optics
Guy P. Delacretaz; Rudolf W. Steiner; Lars Othar Svaasand; Hansjoerg Albrecht; Thomas H. Meier, Editor(s)

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