Testicular dose contributed by X-ray volume image-(XVI)-guided intensity-modulated radiotherapy (IMRT) in prostate cancer patients

Introduction: To assess the dose received by testes during XVI-guided IMRT in prostate cancer patients (PCPs). Material and methods: Testes dose was calculated in 56 PCPs who underwent definitive IMRT using 6 MV or 15 MV photon energies. The dose was measured by thermoluminescent dosimeters (TLDs) MTS-N attached to the scrotum during the first three fractions of IMRT. Testicular concomitant exposure from XVI was measured using a PTW DIADOS E diagnostic dosimeter in ten randomly chosen patients. Results: The mean and standard deviation values of the average calculated testes dose was 123 ± 117 cGy comprising 1.6% of the prescribed total irradiation dose (Dt). A testicular dose measured by TLDs was 303 ± 110.5 cGy (4% of Dt) and depended on the distance from isocenter to testes (r = –0.8). From one XVI scan, the detected testicular mean dose was 4.3 mGy. Mean XVI scan numbers for all patients was 10.4 so mean concomitant dose in testes was 44.7 mGy (0.06% of Dt). Conclusions: Testicular dose may be significant in the aspect of fertility during IMRT in PCPs. Kilovoltage XVI-contributed dose to testes seems to be clinically negligible.