Preliminary Monte Carlo simulation of non-laser light sources for photodynamic therapy

Abstract

In photodynamic therapy (PDT), a photosensitizing agent is administered following irradiation on the target volume. The wavelength beam to activate the photosensitizer is ranging from 400 nm to 800 nm. Such wavelengths are generated by laser and non-laser light sources. However, the use of x-ray induced in photodynamic therapy has been investigated as a combination of radiotherapy and PDT. Moreover, x-rays are used for deeper penetration into tissue, extending the use of this therapy for tumours that would not be reachable by conventional PDT. In general, x-rays with keV to MeV energies are used for X-PDT. The aim of the present work is to investigate the use of monochromatic, low-energy beams for photodynamic therapy applications. Monte Carlo simulations are performed for distinct target volumes irradiated by a nonlaser (low-energy x-rays). Models of soft tissue and a mixture some photosensitizer plus soft tissue were considered. For each case, the energy fluence distribution at a given depth was calculated. A higher percentage difference of ∼20% was found when comparing the beam profile between soft tissue and the mixing Hpd, Photofrin, ALA, PpIX with soft tissue for low energy x-ray. Preliminary results showed that simulated x-ray beams could work for PDT.