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Neutron damage induced in cardiovascular implantable electronic devices from a clinical 18 MV photon beam: A Monte Carlo study
Author(s) -
Ezzati Ahad Ollah,
Studenski Matthew T.
Publication year - 2017
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1002/mp.12581
Subject(s) - neutron , fluence , monte carlo method , photon , dosimetry , physics , beam (structure) , nuclear physics , materials science , nuclear medicine , computational physics , irradiation , optics , medicine , mathematics , statistics
Purpose The purpose of this study was to quantify the relative neutron damage induced in CIED s from clinical 18 MV photon beams for varying field sizes, depths, and off axis distances. Methods and Materials Damage was assessed using silicon damage response functions and ICRP neutron dose conversion factors in MCNPX . Particular attention was devoted to the modelling of the Varian 2100C/D linear accelerator to ensure accurate contamination neutron spectra. Neutron dose, fluence and relative damage to CIED s was calculated. Results CIED damage from neutrons is related to the neutron dose rather than the neutron fluence. As field size increases, the region of high damage probability extends to a greater distance beyond the edge of the field than with smaller fields. At a distance greater than 50 cm or from the central axis or a depth deeper than 10 cm, the probability of damage is less than 10% of the central axis damage probability for all field sizes. Conclusions Clinically, increasing the depth or the distance from the central axis to the CIED will reduce the probability of damage from neutrons. Care must be taken when treating large fields as the overall probability of damage increase as does the distance the higher probability of damage extends beyond the field edge.