Towards Offline PET Monitoring at a Cyclotron-Based Proton Therapy Facility

Matthias Würl
presents two essential steps to implement offline PET monitoring of proton dose
delivery at a clinical facility, namely the setting up of an accurate Monte
Carlo model of the clinical beamline and the experimental validation of
positron emitter production cross-sections. In the first part, the field size
dependence of the dose output is described for scanned proton beams. Both the
Monte Carlo and an analytical computational beam model were able to accurately
predict target dose, while the latter tends to overestimate dose in normal
tissue. In the second part, the author presents PET measurements of different
phantom materials, which were activated by the proton beam. The results
indicate that for an irradiation with a high number of protons for the sake of
good statistics, dead time losses of the PET scanner may become important and
lead to an underestimation of positron-emitter production yields.