Evaluation of lensed fibers used in photodynamic therapy (PDT).

Abstract

The combination of diode laser and lensed optical fiber is a commonly used technique in photodynamic therapy (PDT). The design of the lensed fiber can affect the beam quality, therefore, directly or indirectly effect treatment outcomes. In this study, several commercially available microlens and convex lens fibers used in PDT were evaluated. A total of five types of lensed fibers were evaluated. The beam uniformity, expansion, and transmittance properties of lensed fibers to laser beams of 532 nm and 630 nm were analyzed. In addition, the spectral transmissions of lensed fibers were also examined using a broad band light source (400-1000 nm). Using microlens alone could significantly improve the light beam uniformity. The combination of lens and macrobendings could further improve the light beam uniformity. The beam expansion effect was determined by the numerical aperture (NA) of lens. The microlens fibers of higher NA showed better beam expansion effect than the convex lens of lower NA. The overall transmittance of tested lensed fibers ranged between 70 % and 77 %. Tested fibers showed good transmission property to the tested PDT wavelengths. Generally speaking, utilizing macrobending could improve the transmission quality of lens based frontal fiber-optic light distributors in PDT applications.