Evaluation of Testis functioning during Pelvic Radiotherin the presence of testis lead shield

Introduction: Rectal and bladder cancer are the most common disease among young man. Although External Radiotherapy (EBRT) is one of the most effective treatment options introduced so far, the testis undesired radiation dose increases the risk of infertility and hormonal malfunctioning. The testicles are usually outside of the radiation field, but they can be exposed either to scattered and or direct radiation pending on the distance of radiation field, patient thickness and radiation beam energy. To evaluate testis functioning, the LH, FSH and testosterone levels in rectal and bladder carcinoma and effect of testicular shielding in sex hormonal level during external beam radiotherapy were evaluated. In order to control neutron dose received to the region of interest, shield optimization through Geant4 simulation toolkit was also investigated. Materials and Methods: Thirty patients with bladder and rectal adenocarcinoma received pelvic radiotherapy. All patients received 5040-Gy radiation dose ,1.8Gy/fraction and five days per week. 15 patients were treated without testicular shielding and others received radiotherapy with testicular shielding made of 1.5 centimeter lead. Blood tests were performed before and after radiotherapy for both group. The head of Simens Primus were simulated using Geant4 code. For verification of the simulated linac’s head, the percentage depth doses (PDDs) and Profiles were compared with the corresponding measurements. CT- Structure And Plan Dicom files were then imported to the code and the testicular shield was modelled. Results: Based on the Gamma Index results in the first step and evaluation of optimized shielding, testis dose is minimum. Conclusion: Although the application of routine shield apparently reduces the radiation dose, the neutron dose should also be taken into account. The modified shield including low atomic number materials reduces the radiation dose and improving hormonal functioning.