Light dosimetry for photodynamic therapy by whole bladder wall irradiation.

摘要: In Photodynamic Therapy (PDT) there is a need for accurate quantitative light dosimetry. This has become particularly apparent in the treatment of superficial bladder cancer, either by focal or whole wall irradiation. We have studied this problem using spherical model bladder, consisting two concentric thin-walled plastic spheres, 8 and 10 cm diameter. The inner sphere was filled with water light-scattering medium. space between spheres an optically tissue equivalent liquid. An isotropic source placed at center spheres. Light energy fluence rates (light “dose rates”) during PDT simulated manner, were measured specially developed miniature detector also calculated mathematical model. These data confirmed measurements vivo (dog bladder). case irradiation wavelength 630 nm, ratio (R) true rate surface due to primary beam somewhat larger than 1, depending on diameter beam. maximum 2, several centimeters. PDT, R 5. strong scattering (red) indicates that intensity beam, which usually reported, not good measure PDT. When moved away from change more factor 2 when cavity suspension, as compared water. use medium may therefore be advantageous achieve uniform distribution across wall.