Spatial light distribution in tumors: phantom measurements.
The optical characteristics of 39 excised human tumors are determined. Then liquid phantoms, representative of these tumors, are used to measure the space irradiance in a plane containing the optical axis for two irradiation geometries (external and interstitial) and two wavelengths (514 and 630 nm); a rotating miniature probe allows a spatial resolution of 0.1 mm. It is found that, on the optical axis, the space irradiance at the surface of a phantom is higher than the irradiance applied externally and exhibits a maximum prior to reaching an exponential decrease. A zone where green light is expected to provide better photochemical efficiency than red light is determined and the space irradiance obtained with external and interstitial irradiation are compared quantitatively. The clinical usefulness of the results is limited by the fact that individual samples belonging to the same type of tumor differ considerably in their optical characteristics, at least unless a more detailed classification (based on a greater number of tumor samples) is available.
Lenz
P
P
Institut National de la Santé Et de la Recherche Médicale, U. 281, Lyon, France.
D004067:Digestive System Neoplasms / Q000188:drug therapy; D006801:Humans; D066298:In Vitro Techniques; D008027:Light; D008961:Models, Structural; D009369:Neoplasms / Q000188:drug therapy; D010778:Photochemotherapy