Monte Carlo study of organ doses and related secondary cancer risk estimations for patients undergoing prostate...

The present study aimed to assess organ doses and the associated cancer risks related to secondary radiation (photons and neutrons) exposure during 3D Conformational Radiotherapy (3D-CRT) for patients with prostate cancer in Algeria. To this purpose, a detailed geometric Monte Carlo (MC) modeling of the LINAC, combined with a hybrid whole-body phantom was carried out. The secondary radiation doses were calculated in patient's organs, both within and outside the field. The obtained doses were used to estimate the Lifetime Attributable Risks (LARs) for cancer incidence for out of field organs, using the Biological Effects of Ionizing Radiation VII (BEIR VII) risk model, considering the exposure age range according to the age of the treated patients in Algeria. The survival information and baseline cancer risks were based on relevant statistics for the Algerian population. The results revealed that secondary radiation equivalent doses mostly depend on the distance of organs from the treated volume. The highest and lowest equivalent doses of 5.77 mSv/Gy and 0.24 mSv/Gy were recorded in the small intestine and ocular lens, respectively. LARs decreased as the age of exposure increased, with the highest estimated value per 100,000 individuals identified at a 35-year exposure age (88 for the colon and 15 for the intestine). Conversely, the lowest risks were found at 70 years of age, specifically in rib bone and leg bone with value of (0). The current research could contribute to establishing a database concerning the incidence of secondary cancers induced by radiotherapy during 3D-CRT for prostate cancer in Algeria.