On line neutron dose evaluation in patients under radiotherapy

Current improvements in radiotherapy require methods to evaluate their costs and benefits. A possible counterpart of the benefit is the creation of a secondary, radiation induced cancer. A new procedure is presented to assess the peripheral dose delivered to the patients due to photo-neutrons by means of a new on line digital detector. The events in the monitor have been correlated with the neutron dose by Monte Carlo simulations and experimental measurements using CR39 and TLD. This digital detector was employed at 6 different linacs, with energies ranging from 6 to 23 MV, obtaining the doses received in each organ of the patient. Additionally, the ambient dose equivalent was determined finding values from 0 to 470 mSv for complete treatments.