PET-based proton range monitoring using a SA approach in an inhomogeneous target

The characteristic dose deposition as a function of depth in proton therapy allows for highly conformal dose distributions and better organ sparing. Using beam-induced positron emitters PET scanning is one of the most widely usedfor predicting dose and positrons activity distributions. An inhomogeneous phantom comp procedures for proton therapy verification. A recent study has demonstrated the peak $^{13}$N at the distal dose falloff region. This work is aimed at investigating range monitoring by $^{13}$N using Spectral Analysis (SA) approach. The PHITS Monte Carlo code was used osed with four different materials (PMMA, lung-equivalent, water, and bone-equivalent) was irradiated with monoenergetic (80 MeV) and SOBP (70-80 MeV) fields. The SA extracted $^{13}$N peaks are near or within the real Bragg peaks, while the $^{11}$C and $^{15}$O peaks are far away in case of pristine and SOBP distributions. The results are used to generate a 3D scatter plot of the radioisotopes distribution. The SA extracted results shown good agreement with the simulated one. The comparison between the simulated and SA extracted radioisotopes showed no offset distance along the beam direction. Future investigations into proton range monitoring for therapeutic purposes may benefit from the results obtained.