Estimates of the neutron dose equivalent for occupationally staff exposed and public in facilities radioactive medical use: X-ray beam energy equal and/or greater than 10 MeV

Full text: In Mexico the use of electron accelerators for treating cancerous tumors had grown enormously in the last decade. When the treatments are carried out with X-ray beam energy below 10 MeV the design of the shielding of the radioactive facility is determined by analyzing the interaction of X-rays, which have a direct impact and dispersion, with materials of the facility. However, when it makes use of X-ray beam energy equal to or greater than 10 MeV the neutrons presence is imminent due to their generation by the interaction of the primary beam X-ray with materials head of the accelerator and of the table of treatment mainly. In these cases, the design and calculation of shielding considers the generation of high-energy neutrons which contribute the equivalent dose that public and Occupationally Staff Exposed (POE) will receive in the areas surrounding the facility radioactive. However, very few measurements have been performed to determine the actual contribution to the neutron dose equivalent received by POE and public during working hours. This paper presents an estimate of the actual contribution of the neutron dose equivalent received by public and POE facilities in various radioactive medical use, considering factors such as energy and beam direction of treatment, factors of use and occupancy of the surrounding areas, material and thickness of the shielding as well as the design of the facility itself radioactive. To this end, measurements were made of the equivalent dose by using a neutron monitor in areas surrounding different radioactive installations (of Mexico) which used electron accelerators medical use during treatment with X-ray beam energy equal to or greater than 10 MeV. The results are presented after a statistical analysis of a wide range of measures in order to estimate more reliability real contribution of the neutron dose equivalent for POE and the public. It also presents an interpretation of the potential health effects, primarily for POE, due to the existence of high energy neutrons. (author)