Dose Verification in Lung Radiotherapy Using PET Imaging of Nanoparticle-Induced Positrons

Introduction: Accurate verification of radiation dose delivery remains a major challenge in radiotherapy. Positron emission tomography (PET) imaging of megavoltage (MV)-induced positrons (MVIPET) has recently emerged as a potential in vivo dosimetry technique. In this study, we investigated the feasibility of enhancing MVIPET signals using high-Z nanoparticles (NPs), specifically platinum (Pt) and silver (Ag), to enable real-time dose monitoring during lung radiotherapy. Material and Methods: PET images arising from positrons induced by platinum and silver nanoparticles in a lung tumor were generated during radiotherapy with ۶, ۱۰, and ۱۵ MV photon beams using the GATE Monte Carlo code. The resulting images were evaluated for both image quality and dose verification. Results: Results showed that positron production, absorbed dose, and PET signal intensity increased with both photon beam energy and NP concentration, with PtNPs producing significantly higher enhancement than AgNPs. High-quality MVIPET images with acceptable SBR and CNR, and low RMSE, were obtained for PtNP concentrations ≥۸ wt% at ۱۰ MV and ≥۴ wt% at ۱۵ MV. In contrast, AgNPs required higher concentrations and only yielded reliable monitoring at ۱۵ MV. At ۶ MV, image quality and dose–image correlation were insufficient for clinical feasibility. Conclusion: These findings demonstrate that MVIPET, particularly when combined with PtNPs and higher photon energies, is a promising strategy for real-time, non-invasive dose verification in lung radiotherapy.

کلیدواژه ها:

PET ، Dosimetry ، Radiation Therapy ، Nanoparticle ، Monte Carlo