Phys Med Biol. 2012 Oct 3;57(20):N365-N376. [Epub ahead of print]
Vagus nerve stimulator stability and interference on radiation oncology x-ray beams.
Source
Radiation Oncology Department, Tri-State Regional Cancer Center, 706 23rd Street, Ashland, KY 41101, USA. Regulation Directive Medical Physics LLC®, 3312 Forestdale Court, Flatwoods, KY 41139, USA.Abstract
Five different models of Cyberonics, Inc. vagus nerve stimulation (VNS) therapy pulse generators were investigated for their stability under radiation and their ability to change the absorbed dose from incident radiation. X-ray beams of 6 MV and 18 MV were used to quantify these results up to clinical doses of 68-78 Gy delivered in a single fraction. In the first part, the effect on electronic stimulation signaling of each pulse generator was monitored during and immediately afterwards with computer interrogation. In the second part, the effects of having the pulse generators scatter or attenuate the x-ray beam was also characterized from dose calculations on a treatment planning system as well as from actual radiation measurements. Some device models were found to be susceptible to radiation interference when placed directly in the beam of high energy therapeutic x-ray radiation. While some models exhibited no effect at all, others showed an apparent loss of stimulation output immediately after radiation was experienced. Still, other models were observed to have a cumulative dose effect with a reduced output signal, followed by battery depletion above 49 Gy. Absorbed dose changes on computer underestimated attenuation by nearly half for both energies amongst all pulse generators, although the computer did depict the proper shape of the changed distribution of dose around the device. Measured attenuation ranged from 7.0% to 11.0% at 6 MV and 4.2% to 5.2% at 18 MV for x-rays. Processes of back-scatter and side-scatter were deemed negligible although recorded. Identical results from 6 MV and 18 MV x-ray beams conclude no neutron effect was induced for the 18 MV beam. As there were documented effects identified in this research regarding pulse generation, it emphasizes the importance of caution when considering radiation therapy on patients with implanted VNS devices with observed malfunctions consequential.- PMID:
- 23032351
- [PubMed - as supplied by publisher]
Related citations in PubMed
- Evaluation of a ventricular assist device: stability under x-rays and therapeutic beam attenuation.[ASAIO J. 2012]
- Establishing radiation therapy treatment planning effects involving implantable pacemakers and implantable cardioverter-defibrillators.[J Appl Clin Med Phys. 2009]Establishing radiation therapy treatment planning effects involving implantable pacemakers and implantable cardioverter-defibrillators.Gossman MS, Graves-Calhoun AR, Wilkinson JD. J Appl Clin Med Phys. 2009 Dec 23; 11(1):3115. Epub 2009 Dec 23.
- Build-up and surface dose measurements on phantoms using micro-MOSFET in 6 and 10 MV x-ray beams and comparisons with Monte Carlo calculations.[Med Phys. 2007]
- Inclusion of compensator-induced scatter and beam filtration in pencil beam dose calculations.[Med Phys. 2006]
- Review Dose to normal tissues outside the radiation therapy patient's treated volume: a review of different radiation therapy techniques.[Health Phys. 2008]
No comments:
Post a Comment