Case study of radiation therapy treatment of a patient with a cardiac ventricular assist device

Abstract

A patient with a cardiac ventricular assist device (VAD) with computer-controller driver presented to our department for radiation therapy.  The treatment plan was 4500 cGy to the rectum over 25 fractions with 15MV photon beams.  All beams avoided the pump and leads.  The response to electromagnetic interference (EMI) was evaluated by observing a duplicate driver in the treatment configuration as the patient’s fields were delivered to a solid water equivalent phantom.  Pre-treatment dose assessment included calculations with Pinnacle treatment planning system, AAPM TG36 data analysis, and MOSFET measurements on the surface of the driver during the phantom irradiation.  During the first patient treatment, MOSFETs were placed on the pump and leads, approximately 1cm from the left lateral treatment portal.   No additional shielding was applied to the VAD.  EMI was absent and the VAD operated normally during the pre-treatment test and throughout the treatment course.  Radiation to the driver was too low to be detected by the MOSFETS.  Cumulative dose estimates to the pump were 425cGy to 0.1cc (DVH), 368cGy (TG36), and 158.5cGy (MOSFET).  MOSFET readings to the leads were 70.5cGy.  External beam radiation treatment was safely delivered to a VAD dependent patient.  The VAD exhibited no adverse response to EMI and doses up to 425 cGy.  Our results are based on one case and further study is encouraged.