• dose verification
• FLUKA
• MC simulations
• PET activity study
• protontherapy

Proton therapy exploits proton interactions with matter to treat deep seated tumors with a highly conformal dose while sparing nearby healthy tissues. This high level of conformity necessitates substantial precision in treatment planning and delivery: the charged nature of protons and other sources of random and systematic treatment errors lead to large uncertainties in our knowledge of the delivered proton range.
Because of the required precision, there is an urgent and vital need for an in vivo, non-invasive tool for proton-range monitoring. Positron Emission Tomography (PET) imaging of positron emitters formed as a byproduct of the therapeutic irradiation has been proposed as a method of achieving this goal.
The long-term goal of this project is to develop a semi-automated tool for verifying proton range after proton-therapy treatments by comparing measured and FLUKA Monte-Carlo (MC) simulated PET images.
The aim of this project and of the team in the Department of Radiation Oncology at St. Jude Children’s Research Hospital is to benchmark the MC code capable of simulating PET images. The model is validated using dose comparisons from routine Quality Assurance (QA) procedures: before radiation treatments, the planned dose is verified against the real dose measured in water phantoms to check the plan itself; dose measurements are acquired at multiple depths with a two dimensional ionization chamber array. After model validation through dose comparisons, FLUKA can be used to calculate expected PET activity.
The final step of this work is to obtain PET simulated images with FLUKA to be compared with the measured ones related to craniopharyngioma patients to try to minimize safety margins around the tumors and to better understand range uncertainties, which are the sources of proton range differences.