Pre-treatment dosimetry for interstitial photodynamic therapy

Abstract

A genetic algorithm for optimal placement of optical fibers in arbitrary geometries for interstitial photodynamic therapy has been developed. Based on calculated fiber positions, the diffuse light distribution is simulated by solving the diffusion equation by means of the finite element method and the treatment time is calculated. Utilizing an instrument for interstitial photodynamic therapy that is capable of both delivering the therapeutic irradiation and measuring parameters of relevance to treatment monitoring, knowledge has been gained on temporal variations of tissue light absorption, sensitizer photobleaching and tissue oxygenation status. We speculate on how variations in these three parameters can be implemented in a crude pre-treatment dosimetry model for photodynamic therapy