In-Beam PET Imaging in Carbon Therapy for Dose Verification

Carbon particle therapy has shown great advantages in radiation therapy owing to its high relative biological effectiveness. In-beam positron emission tomography (PET) is an effective method for monitoring and measuring the position and dose of a carbon ion beam. In this paper, we use Geant4 application for emission tomography software to simulate carbon therapy and in-beam PET imaging processes. One hundred pulses of 12 C with 100, 200, and 300 AMeV were impacted on a PMMA target. The distributions of positron-emitting nuclides and the radiation dose were calculated. The coincidence data of annihilation photons from positrons were measured via a small animal PET protocol, which uses the same detector size and ring radius as the MicroPET Focus 220. Finally, we reconstructed the 3-D PET image for the distribution of generated positron-emitting nuclides by using a filtered back projection algorithm, and the PET image was used to determine the position of maximum dose deposition. Thus, we demonstrate a comprehensive method to accurately identify the position of maximum dose deposition by using the reconstructed in-beam PET image.