title: Light penetration in the human prostate: a whole prostate clinical study at 763 nm.
abstract: Photodynamic therapy (PDT) is being investigated as a treatment for localized prostate cancer. Photodynamic therapy uses a photosensitizing drug which is activated by a specific wavelength of light, in the presence of oxygen. The activated drug reacts with tissue oxygen to produce reactive oxygen species which are responsible for localized tissue necrosis. One of the determinants of the PDT effect is the penetration of light in the prostate. This study assesses the penetration depth of 763 nm light throughout the prostate. Eight men undergoing multiple hollow needle insertion for high dose rate brachytherapy were recruited. 763 nm light, produced by a diode laser, was delivered to the prostate using cylindrically diffusing optical fibers within the plastic needles. Light was detected at different distances from the source, using an isotropic detector within nearby needles. Penetration depth was calculated using the Boltzmann approximation to the diffusion equation. Delivery detector fiber separation was measured on computed tomography. The mean penetration depth was 0.57 cm, but there was within patient variation of a mean factor of 4.3. Further work is ongoing to assess the effect of such variability in light penetration, on the PDT effect.
authors.affiliation: National Medical Laser Centre, University College London, Department of Urology, University College London Hospitals Trust, London, NW1 2PG, United Kingdom. carolinemoore@doctors.org.uk
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Moore
authors.forename: C Alexander
authors.initials: CA
authors.lastname: Mosse
authors.forename: Clare
authors.initials: C
authors.lastname: Allen
authors.forename: Heather
authors.initials: H
authors.lastname: Payne
authors.forename: Mark
authors.initials: M
authors.lastname: Emberton
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Bown
mesh_terms: D006801:Humans; D008027:Light; D008297:Male; D009391:Nephelometry and Turbidimetry; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000503:physiopathology* / Q000532:radiotherapy*; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity