Investigation of the Produced Positrons and Their Dose Deposition at Bone and Soft Tissue Organs at Proton Therapy: A Simulation Study

Background & Objective:  Proton therapy has emerged as a superior method in cancer treatment compared to traditional photon-based radiation therapies. Because of the unique physical features of protons and Bragg curve, it can deliver the greatest dosage directly to the tumor while minimizing the radiation absorbed by surrounding healthy tissues. By spreading out Bragg Peak, proton therapy ensures that the tumor receives the prescribed high dose while reducing side effects. In proton therapy, the positrons play a significant role in dose monitoring and imaging.  Materials & Methods:  In this research, GEometry ANd Tracking (GEANT۴) simulation code was used to study the number of positrons emitted and their dose depositions during proton therapy at energies of ۵۰ and ۱۰۰ MeV in both soft tissue and bone with variety of densities. Results:  The results showed that for ۵۰ MeV protons, ۱۵O was identified as the positron emitter that emits the most positrons in both tissues at two energies. The maximum penetration depth of ۵۰ MeV proton beam was ۲۶ mm in soft tissue and ۱۶ mm in bone, while at ۱۰۰ MeV, the depth was ۸۹ mm in soft tissue and ۵۳ mm in bone. Furthermore, the dose deposition by positrons decreases by increasing tissue density. Conclusion:  In proton therapy ۵۰ and ۱۰۰ MeV the most positrons emitted from ۱۵O, ۱۱C, ۳۰P, ۱۳N, ۳۸k, ۳۹Ca in soft tissue and bone.

کلیدواژه ها:

Proton therapy ، Positron emitters ، Dose deposition ، GEANT۴ simulation code