title: Multiple-fiber probe design for fluorescence spectroscopy in tissue.
abstract: The fiber-optic probe is an essential component of many quantitative fluorescence spectroscopy systems, enabling delivery of excitation light and collection of remitted fluorescence in a wide variety of clinical and laboratory situations. However, there is little information available on the role of illumination--collection geometry to guide the design of these components. Therefore we used a Monte Carlo model to investigate the effect of multifiber probe design parameters--numerical aperture, fiber diameter, source--collection fiber separation distance, and fiber-tissue spacer thickness--on light propagation and the origin of detected fluorescence. An excitation wavelength of 400 nm and an emission wavelength of 630 nm were simulated. Noteworthy effects included an increase in axial selectivity with decreasing fiber size and a transition with increasing fiber-tissue spacer size from a subsurface peak in fluorophore sensitivity to a nearly monotonic decrease typical of single-fiber probes. We provide theoretical evidence that probe design strongly affects tissue interrogation. Therefore application-specific customization of probe design may lead to improvements in the efficacy of fluorescence-based diagnostic devices.
authors.affiliation: Wellman Laboratories of Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA. josh@eob.cdrh.fda.gov
authors.forename: T Joshua
authors.initials: TJ
authors.lastname: Pfefer
authors.forename: Kevin T
authors.initials: KT
authors.lastname: Schomacker
authors.forename: Marwood N
authors.initials: MN
authors.lastname: Ediger
authors.forename: Norman S
authors.initials: NS
authors.lastname: Nishioka
mesh_terms: D000818:Animals; D003198:Computer Simulation; D004867:Equipment Design; D005336:Fiber Optic Technology / Q000295:instrumentation*; D006801:Humans; D008962:Models, Theoretical; D009010:Monte Carlo Method; D055100:Optical Fibers; D013050:Spectrometry, Fluorescence / Q000295:instrumentation*