Direct proton range verification using oxygen-18 enriched water as a contrast agent

We propose the use of 18O-enriched water as a suitable contrast agent for potential in-vivo range verification in proton therapy. The low energy production threshold 18F (2.6 MeV, 115 μm) leads to tissue activation very close proximity maximum dose deposition, facilitating accurate with off-line PET imaging. This idea has been explored phantom experiment. A 3D-printed containing inserts was irradiated 100-MeV, 8 × cm2 beam, and induced activity measured small-animal PET-CT 30 min after irradiation. images obtained were compared against Monte Carlo simulation using TOPAS. Good agreement observed between reconstructed simulated profiles (within 40% specific activity), excellent spatial match deposition. Because long half-life 18F, could be separated clearly more than 2 h Activity distribution maps used determine position Bragg peak within mm three different regions interest. These results show