title: Detection of localized inclusions of gold nanoparticles in Intralipid-1% by point-radiance spectroscopy.
abstract: Interstitial fiber-optic-based approaches used in both diagnostic and therapeutic applications rely on localized light-tissue interactions. We present an optical technique to identify spectrally and spatially specific exogenous chromophores in highly scattering turbid media. Point radiance spectroscopy is based on directional light collection at a single point with a side-firing fiber that can be rotated up to 360 deg. A side firing fiber accepts light within a well-defined, solid angle, thus potentially providing an improved spatial resolution. Measurements were performed using an 800-μm diameter isotropic spherical diffuser coupled to a halogen light source and a 600 μm, ∼43 deg cleaved fiber (i.e., radiance detector). The background liquid-based scattering phantom was fabricated using 1% Intralipid. Light was collected with 1 deg increments through 360 deg-segment. Gold nanoparticles , placed into a 3.5-mm diameter capillary tube were used as localized scatterers and absorbers introduced into the liquid phantom both on- and off-axis between source and detector. The localized optical inhomogeneity was detectable as an angular-resolved variation in the radiance polar plots. This technique is being investigated as a potential noninvasive optical modality for prostate cancer monitoring.
authors.affiliation: University of Prince Edward Island, Department of Physics, Charlottetown, Prince Edward Island Canada C1A 4P3. sgrabtchak@upei.ca
authors.forename: Serge
authors.initials: S
authors.lastname: Grabtchak
authors.forename: Tyler J
authors.initials: TJ
authors.lastname: Palmer
authors.forename: William M
authors.initials: WM
authors.lastname: Whelan
mesh_terms: D003952:Diagnostic Imaging; D004655:Emulsions; D006046:Gold / Q000737:chemistry; D006801:Humans; D008297:Male; D053768:Metal Nanoparticles / Q000737:chemistry*; D055620:Optical Phenomena; D019047:Phantoms, Imaging; D010743:Phospholipids; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000628:therapy; D013024:Soybean Oil; D013057:Spectrum Analysis / Q000295:instrumentation / Q000379:methods*
chemical_list: D004655:Emulsions; D010743:Phospholipids; C545823:soybean oil, phospholipid emulsion; D006046:Gold; D013024:Soybean Oil