Document Detail

Vagus nerve stimulator stability and interference on radiation oncology x-ray beams.
MedLine Citation:
PMID:  23032351     Owner:  NLM     Status:  Publisher    
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.
Michael S Gossman; Amruta Ketkar; Arthur K Liu; Bryan Olin
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-03
Journal Detail:
Title:  Physics in medicine and biology     Volume:  57     ISSN:  1361-6560     ISO Abbreviation:  Phys Med Biol     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-3     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0401220     Medline TA:  Phys Med Biol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  N365-N376     Citation Subset:  -    
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.
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