03/25/2024
By Arianna Liles

The Kennedy College of Sciences, Department of Physics and Applied Physics, invited you to attend a master’s thesis defense by Arianna Liles on “Pacemaker performance during and after in-vitro radiation.”

Candidate Name: Arianna Liles
Degree: MS
Date: Friday, April 5, 2024
Time: 10–11 a.m.
Location: This will be a virtual defense via Zoom. Those interested in attending should contact MS candidate arianna_liles@student.uml.edu at least 24 hours prior to the defense to request access to the meeting.

Committee Members:

  • Advisor: Jeremy Bredfeldt, Ph.D., DABR, Assistant Professor of Radiation Oncology, Harvard Medical School
  • Erno Sajo, Ph.D., Professor, Department of Physics and Applied Physics, University of Massachusetts Lowell
  • James Egan, Ph.D., Professor, Department of Physics and Applied Physics, University of Massachusetts Lowell
  • John Whitaker, Ph.D., Clinical Senior Lecturer, King’s College London

Thesis Title: Pacemaker performance during and after in-vitro radiation

Abstract: 

The cost and complexity of managing pacemaker dependent patients receiving radiation therapy is a significant burden. AAPM Task Group 203 (TG203) recommends implantable cardiac pacemaker (ICP) dependent patients receive elevated precautions such as mid-treatment interrogations and magnet placement, which result in significant time costs. This work studies ICP functionality in clinically relevant radiation therapy conditions and measures the failure rates of the devices in the context of an ICP dependent patient. 15 Medtronic devices – 5 single chamber, 5 dual chamber, and 5 Micra – were exposed to radiation from 6MV, 6FFF, 10MV, 10FFF beams 1cm outside the field edge for 30 seconds at the maximum repetition rate on TrueBeam and Ethos LINACs. The dose rates ranged from 0.22Gy/min to 1.51Gy/min. Real-time electrogram data were collected during beam-on and beam-off. Battery checks were also performed before irradiation and six months post-irradiation, and the timing between pacing spikes was measured during the beam-on and -off times. No artifacts or malfunctions were observed throughout all experiments across all types of ICPs. More pacing spike timing outliers were observed during beam-on, however the largest outliers still remained within a clinically insignificant range. Battery life showed normally expected depletion six months after irradiation. Further investigation will expose devices to higher dose rates irradiated directly in the beam to study potential device failures.