title: Evaluation of a ventricular assist device: stability under x-rays and therapeutic beam attenuation.
abstract: Improved outcomes and quality of life of heart failure patients have been reported with the use of left ventricular assist devices (LVADs). However, little information exists regarding devices in patients undergoing radiation cancer treatment. Two HeartWare Ventricular Assist Device (HVAD) pumps were repeatedly irradiated with high intensity 18 MV x-rays to a dosage range of 64-75 Gy at a rate of 6 Gy/min from a radiation oncology particle accelerator to determine operational stability. Pump parameter data was collected through a data acquisition system. Second, a computerized tomography (CT) scan was taken of the device, and a treatment planning computer estimated characteristics of dose scattering and attenuation. Results were then compared with actual radiation measurements. The devices exhibited no changes in pump operation during the procedure, though the titanium components of the HVAD markedly attenuate the therapy beam. Computer modeling indicated an 11.8% dose change in the absorbed dosage that was distinctly less than the 84% dose change measured with detectors. Simulated and measured scattering processes were negligible. Computer modeling underestimates pretreatment dose to patients when the device is in the field of radiation. Future x-ray radiation dosimetry and treatment planning in HVAD patients should be carefully managed by radiation oncology specialists.
authors.affiliation: Tri-State Regional Cancer Center, Radiation Oncology Department, Ashland, Kentucky 41101, USA. mgossman@tsrcc.com
authors.forename: Michael S
authors.initials: MS
authors.lastname: Gossman
authors.forename: Joel D
authors.initials: JD
authors.lastname: Graham
authors.forename: Dan
authors.initials: D
authors.lastname: Tamez
authors.forename: Neil
authors.initials: N
authors.lastname: Voskoboynikov
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Larose
mesh_terms: D003198:Computer Simulation; D006353:Heart-Assist Devices; D006801:Humans; D009369:Neoplasms / Q000532:radiotherapy*; D010315:Particle Accelerators; D011829:Radiation Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012542:Scattering, Radiation; D014965:X-Rays