ESTRO 2023 - Abstract Book

S246

Saturday 13 May

ESTRO 2023

Pacing voltage change >25%

Pacing voltage reduction >10% <25%

No clinically relevant failures recorded

Dose Rate

Beam Regime

CIED Mode

Other recorded errors

6X

48Gy/8# 6Gy/min Normal

Not collected Not collected

1/45 (2%) Pacing inhibition 44/45 (98%)

8/49 (16%) Pacing inhibition

1/49 (2%) Inappropriate shock

10FFF 48Gy/1# 24Gy/min Normal

Not collected Not collected

38/49 (78%)

2/49 (4%)* Device reset * model subsequently recalled by manufacturer on safety notice

6X

48Gy/8# 6Gy/min Asynchronous 0/19 (0%)

Not collected

Not collected

19/19 (100%)

2/21 (10%)* *Increase in pulse voltage

10FFF 48Gy/1# 24Gy/min Asynchronous

Not collected

Not collected

19/21 (90%)

10FFF 60Gy/5# 12Gy/min Asynchronous 0/13 (0%) 10FFF 60Gy/5# 24Gy/min Asynchronous 0/13 (0%)

2/13 (15%) 3/13 (23%)

Not collected Not collected

13/13 (100%) 13/13 (100%)

Conclusion 6X treatments of 6Gy/#, to a cumulative dose of 48Gy, far in excess of current guideline limits, were found to not affect CIED pacing output while in asynchronous mode. Inappropriate defibrillation or device reset were also not found under normal CIED operation modes. These results suggest current dose limits using 6X could be significantly increased using these parameters, reducing constraints on choice of treatment plan and dose distributions. 10FFF deliveries to CIEDs in asynchronous mode found a clinically insignificant reduction 10%<20% of output voltage only after a total of 24Gy was delivered. However, more data is felt required to suggest any revision of guidelines with 10FFF beams. MO-0311 Radiotherapy-related CIEDs dysfunctions in the Lille University Hospital remote monitored patients M. Noeuveglise 1 , L. Finat 2 , C. Kouakam 2 , C. Marquié 2 , D. Klug 2 , T. Lacornerie 3 , E. Rault 3 , X. Mirabel 1 , L. Guédon-Moreau 2 1 Oscar Lambret Center, Radiotherapy, Lille, France; 2 Lille University Hospital, Heart and Lung Institute, Cardiovascular Medicine, Lille, France; 3 Oscar Lambret Center, Medical Physics, Lille, France Purpose or Objective The indications for cardiovascular implantable electronic devices (CIEDs) including defibrillators and pacemakers, are increasing, as is the cancer burden for older patients. Recommandations have been published, but the interactions between CIEDs and ionising radiations are insufficiently known by radiotherapy medical teams and cardiology teams. The production of secondary neutrons by the use of high energy beams (superior to 10MV). Telecardiology is a major asset for the monitoring of these patients. The objective of this study, is to analyze the radiotherapy related CIEDs dysfunctions (reversion of the device to back-up mode) in a cohort of patients followed by remote monitoring of their device in the Lille University Hospital. Materials and Methods In 2009, at Lille University Hospital, a single-center register was designed to prospectively analyze the alerts form remote monitoring of CIEDs, regardless of the device manufacturer. All the alerts received through these remote monitoring systems were included in the register, and were classified as clinical or technical alerts. Technical alerts included lead related alerts and device-related alerts. Clinical alerts included arrhythmias and heart failure-related alerts. For the purpose of the present study, the technical device-related alerts arising from reversion to back-up mode were extracted from the register, and their cause was described and analyzed. Results 2745 patients were enrolled over a mean follow-up of 3.5 years. Among 89,806 event-triggered transmissions, 17,505 were classified as technical alerts. Only 20 alerts were related to reversion to back-up mode, with 8 of them caused by radiotherapy in 7 patients. None of these alerts was followed by a clinical adverse event before the CIEDs problem was resolved. For 8 of these alerts, 7 had their CIEDs out of field. All patients were treated with high Energy X-Rays, ranging from 18 to 25MV. For the patient with in field CIED, the dose to the device was less than 0,3Gy. The localisations of the radiotherapy were : Pelvic (5 patients), Encephalic (1 patient), controlateral lung apex (1 patient). Conclusion All the alerts involving CIEDs and radiotherapy in this population were associated with high energy X-rays. Radiation oncologist should avoid using X-rays with an energy superior to 10MV when treating patients with CIEDs, even if the device is far from the field. Poster Discussion: Technical improvements in radiotherapy practice

PD-0312 Audit of prostate cancer planning CT rescan rate and value S. Alexander 1 , H. McNair 1 , U. Oelfke 2 , C. Ockwell 3 , A. Tree 4

1 The Royal Marsden NHS Foundation Trust/ The Institute of Cancer Research, Radiotherapy, Sutton, United Kingdom; 2 The Royal Marsden NHS Foundation Trust/ The Institute of Cancer Research, Joint department of physics, Sutton, United