Two shielding protection disks systems in breast intraoperative irradiation

Introduction Intraoperative electron beam radiotherapy (IOERT) consists in treating tissue suffering from neoplastic processes, made accessible by surgery. Even if the particular characteristics of the beam define the target area, the presence of organ at risk (OAR) around the irradiation field has to be considered. Purpose The aim of this study is to evaluate the effectiveness of shielding protection disk used in breast intraoperative irradiation to protect OAR. Materials and methods We used two different dosimetric system (Gafchromic™ films and Mosfet dosimeters), for characterization of the attenuation properties of different shielding protection disks, using two different accelerators. The dosimetric systems were calibrated using the same LINAC. The attenuation factor of the shielding disks has been carried out with clinical IOERT irradiation of 10 Gy in solid phantom. The disks were positioned at depth of maximum dose (D max ), and at the depth of 90% dose (D 90 ), corresponding to the typical depth of dose prescription in IOERT irradiation. Results PMMA measurements show an attenuation factor less than 50% for all beam qualities, using both accelerators; the PTFES their use is suitable as protection device in breast IOERT. The consistency of these different dosimetric systems lead to a feasible application for in-vivo dosimetry.