Induced radioisotopes in a lilac treatment hall

Abstract

When linacs operate above 8 MV an undesirable neutron field is produced whose spectrum has three main components, the direct spectrum due to those neutrons leaking out from the linac head, the scattered spectrum due to neutros produced in the head that collides with the nuclei in the head losing energy and the third spectrum due to room-return effect. The third category of spectrum has mainly ephitermal and thermal neutrons being constant at any location in he treatment hall. These neutrons induce activation in the linac components, the concrete walls and the patient body. Here the induced radioisotopes have been identified in concrete samples located in the hall and in one of the wedges. The identification has been carried out using a gamma-ray spectrometer.