Use of Bubble Detectors to Measure Neutron Contamination of a Medical Accelerator Photon Beam

Medical electron accelerators generate spurious neutron radiations; in order to protect patients, neutron radiation levels must remain below internationally recommended values. In the present study, bubble detectors were used to measure the neutron component in the primary beam and outside the radiation field for 8, 15, 18 and 25 MV photons from a Saturne 43F type medical accelerator. The results are compared with those obtained using other methods. Values of between 0.25 and 7.5 mSv.Gy-1 were determined at the beam isocentre for photons of 8 to 25 MV; these values are in agreement with those published in the literature.