A MC tool for CT-based calculations of dose delivery and activation in proton therapy

Abstract

The feasibility and value of offline PET/CT imaging for in-vivo, non-invasive verification of proton beam delivery is currently under investigation at Massachusetts General Hospital, Boston. Within this project we have developed a Monte Carlo framework for CT-based calculation of dose and irradiation induced positron emitter distributions using the FLUKA Monte Carlo code. Particle transport in the patient is performed on the CT grid, taking into account realistic tissue composition as well as the correlation between CT numbers and stopping power ratio to water as used by the commercial treatment planning system (XiO, Computerized Medical System Inc.). Positron emitter production is computed by combining during runtime proton fluence with experimental and evaluated cross-sections for all the major reaction channels yielding measurable tissue activation. In this paper we describe our dedicated implementation which might be easily generalised for use in other proton therapy centres or extended to include further activation reaction channels, provided that initial beam information or experimental cross sections are known. Further, we present clinical examples for calculation of delivered dose and irradiation induced PET activation. © 2007 IOP Publishing Ltd.