Simulations of a new PET scanner for 3D proton therapy quality assurance

In proton therapy, a conformal and precise radiation dose is delivered to tumors, resulting in improved treatment outcomes and higher survival rates. However, the depth-dose profile (Bragg Peak) poses a significant concern for clinical applications, as even minor spatial uncertainties can lead to undesired doses in normal tissues. Imaging techniques like Positron Emission Tomography (PET) have been proposed to address this challenge. This study evaluates the suitability of the easyPET.3D system for assessing 3D proton beam profiles through Monte Carlo simulations. The primary focus is on accurately predicting the distribution of<i>β</i>⁺emitters produced in a phantom after proton beam irradiation. Simulations were performed to model the irradiation of homogeneous and heterogeneous phantoms with monoenergetic protons (energies ranging from 80 to 160 MeV) and obtain the corresponding PET images of the phantom's irradiation. The<i>β</i>⁺production map (ground truth) generated in the phantoms showed reproducible agreement with the PET image obtained. For the energy beams simulated in this study, the relative deviation between the ground truth image and the PET 3D image was less than 14%, for every beam energy. The easyPET.3D system could also differentiate between the two materials in the heterogeneous phantom. Additionally, the distance between the Bragg peak and the maximum intensity of PET image profile obtained remained constant across all simulated proton energy beams, around 11.7 mm. This suggests that the easyPET.3D system can be used as an effective tool to assess beam quality in proton therapy by measuring the<i>β</i>⁺activation map generated in phantoms and correlate it with the beam's profile.