Implementation of Monte Carlo based PET verification of ion beam delivery into a TPS

Objective To develop and implement an ion beam teletherapy verification system based upon simulations of induced radioactivity and comparison with patient positron emission tomography (PET) scans. Methods A Monte Carlo algorithm was integrated into an in-house built treatment, information, management, and planning system (TIMPS®) to calculate distributions of positron emitters induced by ion beams. These distributions are processed to simulate PET images taking into account positron diffusion, radioactive decay, biological washout, and detector blurring. Additional tools were developed to register simulated PET images with planning CT images and perform comparisons of measured and simulated PET images. Results Production cross-sections were generated for various isotopes and materials. Treatment plans for several different body sites were used to verify the functioning and utility of the new tools for both proton and carbon ion beams. Conclusions Several tools have been developed to simulate PET scans of patients irradiated with ion beams and compare the simulated images to measurements. After commissioning and implementation into the clinic, the appropriate sizes for margins that account for uncertainties may be investigated.