Dosimetric comparison between different radiotherapy protocols for prostate cancer using Geant4 Monte Carlo simulation

Abstract

Abstract We aimed to evaluate absorbed doses received by organs at risk (OARs) following prostate treatment with external beam radiotherapy (EBRT), using different techniques (3D-CRT and box), number of fields (4 and 6 fields) and photon energies (6 and 10 MV). The MIRD5 adult male anthropomorphic phantom in GEANT4 package was used. However, the prostate, rectum and both femoral heads were not available, hence, were created within the phantom. A dose of 75 Gy was prescribed to the prostate, in all simulated treatments. Field size of 6.4 × 5.9 cm2 was used in all techniques. For 3D-CRT technique, beams with similar shape to the prostate were used, while for box technique, square-shaped beams were used. Absorbed doses to OARs (rectum, urinary bladder and both femoral heads) were then evaluated. The 3D-CRT technique resulted in lower dose to OARs compared to box technique. Also, the findings show an inverse relationship between number of fields and the OARs doses. There was no dose difference between the OARs with different beam energies. In conclusion, the 6-field 3D-CRT technique with 6 MV photon beam is an ideal treatment option for prostate cancer.