Dosimetric study to assess the feasibility of intraoperative radiotherapy with electrons (ELIOT) as partial breast irradiation for patients with cardiac implantable electronic device (CIED)

PurposeTo report in-vivo dosimetry in the infraclavicular region, a potential site of a cardiac implantable electronic device (CIED) and to evaluate the absorbed dose from intraoperative radiotherapy with electrons (ELIOT).Methods27 non-cardiopathic breast cancer (BC) patients without CIED received quadrantectomy and ELIOT as partial breast irradiation. Before delivering ELIOT, two catheters, each containing eight thermoluminescent dosimeters (TLDs), were positioned in the infraclavicular region. TLDs internal catheter was located deep in the tumor bed while the external catheter was placed on patient's skin.ResultsData were available for 24/27 patients. The absorbed doses were referred to the dose of 21Gy. Values measured by the external catheter were low, although statistically significant higher doses were found close to the applicator (mean values 0.26-0.49Gy). External TLD doses in proximity of the applicator were lower than those detected by their internal counterparts. Values measured by the internal catheter TLDs varied according to the distance from the applicator while no correlation with tumor site and beam energy was found. The distance from the applicator to deliver <2Gy to a CIED was 2cm, while from 2.5cm the dose measured in all the patients became negligible.ConclusionsThis dosimetric study provided data to support the clinical use of ELIOT in BC patients having CIEDs as long as the suggested minimum safe distance of 2.5cm is taken from the RT field in case of ELIOT single dose of 21Gy, in the energy range of 6-10MeV.