ESTRO 37 Abstract book

ESTRO 37

S613

performed before, after and monitored during every RT session only in PM-dependent or ICD patients; anti-tachy therapies have never been disabled. Only patients receiving a calculated maximal dose absorbed by the device higher than 2 Gy or when the efficacy of RT would have been compromised by the device itself, were considered candidates to surgical repositioning of the device.

Conclusion Despite using VMAT techniques, we were unable to achieve ovarian dose under 1.5Gy, considered necessary not to alter the ovarian function. Moving ovaries further away from treatment fields could be an option to improve future treatments. Farther follow up might also be needed to asses if a longer time is necessary to recovery of ovarian function. (Figure 1)

Results Between June 2010 and December 2016, we enrolled 70 consecutive patients treated on chest, abdomen or head and neck district, most of them receiving volumetric Intensity Modulation RT (IMRT)/IGRT. In those patients who received RT on the abdomen, the maximum absorbed dose was significantly less than in the others (p < 0.0001); nevertheless, we did not observe any statistically significant difference in the analyzed electrical parameters (P and R wave amplitude, pacing threshold, lead impedance and residual duration of the battery estimated by the device itself). Only one patient was candidate to surgical repositioning of the device. We observed only two complications (2.83%): in one patient, the RV pacing threshold increased by 1.5 fold (threshold post-RT 1.2 V @ 0.5 msec), in the second one we found a drastic reduction in the battery life (pre-RT estimated life 1.5 yrs, post-RT < 0.5 yrs., needing an urgent device replacement). In both case the maximal absorbed dose at the device was lower than 2 Gy. Conclusion Radiotherapy is a safety treatment even in patients with PM or ICD. Even if IGRT can reduce the absorbed dose to the device, a standardized protocol is useful because it allows unnecessary removals of the device and a prompt detection of eventual damages, even in pts generally defined at low risk. PO-1088 Pattern of late dysphagia after IMRT of head and neck cancers: a prospective study D. Delishaj 1 , S. Ursino 1 , A. Cristaudo 1 , A. Molinari 1 , F. Orlandi 1 , P. Coccuzza 2 , V. Seccia 3 , P. Giusti 4 , F. Pasqualetti 1 , S. Santopadre 5 , R. Morganti 6 , S. Montrone 1 , D. Baldaccini 1 , A. Gonnelli 1 , A. Nacci 3 , B. Fattori 5 , F. Paiar 1 1 Azienda Ospedaliero Universitaria Pisana, Radiotherapy, Pisa, Italy 2 Institute Gustave Roussy, Radiotherapy, Paris, France 3 Azienda Ospedaliero Universitaria Pisana, First Otorhinolaryngology Unit, Pisa, Italy 4 Azienda Ospedaliero Universitaria Pisana, Radiology, Pisa, Italy 5 Azienda Ospedaliero Universitaria Pisana, Otorhinolaryngology-Audiology-Phoniatric Unit, Pisa, Italy

PO-1087 Radiotherapy (RT) and cardiac implantable electronic devices (CIEDs): a prospective study. E. Villa 1 , F. Michelotti 2 , M. Motta 1 , A. Ravasio 1 , D. Gherardi 1 , V. Manazzale 1 , F. Locatelli 1 , L. Trombetta 1 , P. Salmoiraghi 1 , G. Mascioli 2 , V. Vavassori 1 1 Humanitas Gavazzeni, Radiotherapy and Radiosurgery, Bergamo, Italy 2 Humanitas Gavazzeni, Electrophysiology, Bergamo, Italy Purpose or Objective The number of implanted CIEDs is increasing, as well as the improvement of RT techniques for the treatment of cancer. So, is more and more frequent that a patient with CIED undergoes RT. It is well established that RT can determine electromagnetic interference with CIED but available data on the frequency and cause of CIED failure during radiation therapy are limited and the management of these kind of pts is unclear. Although there is no clear cut-off point nor a clear linear relationship, an adsorbed dose at the device lower than 2 Gy is considered safe (low risk). Aim of this study is to evaluate the effectts of RT on CIEDs in a prospective cohort of pts managed according to a multidisciplinary task force defined protocol. Material and Methods In accord to an internal protocol, all patients undergo an 'in clinic' control of the device before the firs t session and at the end of the RT cycle, while an ECG is