title: Measuring dose from radiotherapy treatments in the vicinity of a cardiac pacemaker.
abstract: This study investigated the dose absorbed by tissues surrounding artificial cardiac pacemakers during external beam radiotherapy procedures. The usefulness of out-of-field reference data, treatment planning systems, and skin dose measurements to estimate the dose in the vicinity of a pacemaker was also examined. Measurements were performed by installing a pacemaker onto an anthropomorphic phantom, and using radiochromic film and optically stimulated luminescence dosimeters to measure the dose in the vicinity of the device during the delivery of square fields and clinical treatment plans. It was found that the dose delivered in the vicinity of the cardiac device was unevenly distributed both laterally and anteroposteriorly. As the device was moved distally from the square field, the dose dropped exponentially, in line with out-of-field reference data in the literature. Treatment planning systems were found to substantially underestimate the dose for volumetric modulated arc therapy, helical tomotherapy, and 3D conformal treatments. The skin dose was observed to be either greater or lesser than the dose received at the depth of the device, depending on the treatment site, and so care should be if skin dose measurements are to be used to estimate the dose to a pacemaker. Square field reference data may be used as an upper estimate of absorbed dose per monitor unit in the vicinity of a cardiac device for complex treatments involving multiple gantry angles.
authors.affiliation: Royal Brisbane and Women's Hospital, Butterfield Street, Herston, QLD 4029, Australia; School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001, Australia. Electronic address: Samuel.Peet@health.qld.gov.au.
authors.forename: Samuel C
authors.initials: SC
authors.lastname: Peet
authors.affiliation: Royal Brisbane and Women's Hospital, Butterfield Street, Herston, QLD 4029, Australia.
authors.forename: Rachael
authors.initials: R
authors.lastname: Wilks
authors.affiliation: Genesis Cancer Care Queensland, 1/40 Chasely Street, Auchenflower, QLD 4066, Australia; School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001, Australia.
authors.forename: Tanya
authors.initials: T
authors.lastname: Kairn
authors.affiliation: Royal Brisbane and Women's Hospital, Butterfield Street, Herston, QLD 4029, Australia; School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001, Australia.
authors.forename: Scott B
authors.initials: SB
authors.lastname: Crowe
mesh_terms: D006801:Humans; D010138:Pacemaker, Artificial; D019047:Phantoms, Imaging; D011874:Radiometry; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated; D035501:Uncertainty
keywords: Cardiac device; Out-of-field dose; Pacemaker; Radiotherapy