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Title: National dosimetric audit network finds discrepancies in AAA lung inhomogeneity corrections.
Epworth Authors: Kenny, John
Other Authors: Dunn, Leon
Lehmann, Joerg
Kron, Tomas
Alves, Andrew
Cole, Andrew
Zifodya, Jackson
Williams, Ivan
Keywords: Epworth Radiation Oncology
Dosimetry, Radiation
Radiation Dosimetry
Dosimetry Calculations, Computer-Assisted
Radiotherapy Planning, Computer-Assisted
Radiotherapy Dose Fractionation
Anisotropic Analytic Algorithm (AAA)
Australian Clinical Dosimetry Service (ACDS)
Treatment Planning System
Issue Date: Apr-2015
Publisher: Elsevier
Citation: Physica Medica 2015; 31: 435-441
Abstract: This work presents the Australian Clinical Dosimetry Service's (ACDS) findings of an investigation of systematic discrepancies between treatment planning system (TPS) calculated and measured audit doses. Specifically, a comparison between the Anisotropic Analytic Algorithm (AAA) and other common dose-calculation algorithms in regions downstream (Math Eq) from low-density material in anthropomorphic and slab phantom geometries is presented. Two measurement setups involving rectilinear slab-phantoms (ACDS Level II audit) and anthropomorphic geometries (ACDS Level III audit) were used in conjunction with ion chamber (planar 2D array and Farmer-type) measurements. Measured doses were compared to calculated doses for a variety of cases, with and without the presence of inhomogeneities and beam-modifiers in 71 audits. Results demonstrate a systematic AAA underdose with an average discrepancy of 2.9 ± 1.2% when the AAA algorithm is implemented in regions distal from lung-tissue interfaces, when lateral beams are used with anthropomorphic phantoms. This systemic discrepancy was found for all Level III audits of facilities using the AAA algorithm. This discrepancy is not seen when identical measurements are compared for other common dose-calculation algorithms (average discrepancy −0.4 ± 1.7%), including the Acuros XB algorithm also available with the Eclipse TPS. For slab phantom geometries (Level II audits), with similar measurement points downstream from inhomogeneities this discrepancy is also not seen.
DOI: 10.1016/j.ejmp.2015.04.002
PubMed URL:
ISSN: 1120-1797
Journal Title: Physica Medica
Type: Journal Article
Affiliated Organisations: Australian Clinical Dosimetry Service, Yallambie, Victoria, Australia
Institute of Medical Physics, University of Sydney, Sydney, Australia
Australian Radiation Protection and Nuclear Safety Agency, Yallambie, Victoria, Australia
School of Applied Science, RMIT University, Melbourne, Victoria, Australia
Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
North West Cancer Centre, Tamworth Hospital, Tamworth, NSW, Australia
Type of Clinical Study or Trial: Descriptive Study
Appears in Collections:Radiation Oncology

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