A Monte Carlo Investigation of the Influence of Initial Electron Beam Characteristics on the Absorbed Dose Distributions Obtained with a 9 Mev Iort Accelerator

The Intraoperative Radiation Therapy (IORT) is a specialized irradiation technique which allows delivering a single high radiation dose (20 – 25 Gy), during the surgical intervention, after the resection of the visible tumour [1]. The advantages of the IORT technique are multiple: (a) the prescribed dose is delivered directly to the tumour bed in which, after the surgical intervention, there is a higher probability to retrieve neoplastic cells that is, therefore, subject to greater risk of local recurrence, (b) the visual control of the target volume, (c) the possibility to protect healthy tissues by moving them away from the path of the radiation beam, and (d) the possibility to administrate a homogeneous dose to a selected layer of tissues surrounding the tumour. The IORT technique can also be used to irradiate the initial cancers of small volume or in unresectable