Abstract: Treatment of a solid tumor with photodynamic therapy (PDT) requires interstitial illumination, since the penetration depth of visible light in tissue is limited. Accurate light dosimetry in solid tumors requires the use of a mathematical model describing light propagation in tissue. By comparing the modeled fluence with measurements of fluence in tissue, the optical coefficients of the tissue can be found. We prefer to use a flat cleaved probe for measurements of the fluence in tissue instead of a spherical probe. In comparing the results of the model to the experimental data, we must deal with the fact that the model gives us the radiant fluence, while the experimental data is the power measured by the flat cleaved fiber with non-isotropic response. Measurements of the angular fluence in a tissue phantom show that the degree of anisotropy in angular fluence decreases with increasing distance from the source. The same result is found in chicken muscle. A calibration factor which modifies the measurements of fluence with a flat cleaved probe to account for the change in anisotropy in the angular fluence is presented. !9
展开▼
