Integrated light dosimetry system for prostate photodynamic therapy.

A light dosimetry system is developed for prostate PDT, which integrates four main components: a light fluence rate calculation engine, an optimization tool for treatment planning, a light delivery system, and an in vivo light fluence rate measurement system. Three-dimensional light fluence rate distribution in a prostate is calculated using a kernel algorithm, which takes into account of heterogeneous optical properties. A Cimmino optimization algorithm is used to optimize the parameters of the cylindrical diffusing fibers (CDFs) to generate uniform PDT dose (or light fluence rate under uniform drug distribution) to cover the heterogeneous prostate. The light delivery system is composed of a 12-channel beamsplitter and the intensities of each channel (i.e., source) are controlled individually by programmable motorized attenuators. Our tests show that the light fluence rate calculation is fast and the accuracy is close to that of a finite-element method model, and the approach that uses the treatment CDFs to determine optical properties, improves the accuracy of light fluence rate prediction. The light delivery system allows real time control of the light source intensities for both PDT dosimetry and PDT light delivery. Integrating the fast light fluence rate calculation, optimization, instant source intensity adjustment, and in vivo light fluence rate measurement, the dosimetry system is suitable for prostate PDT.