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- Title
A Validation Method for EPID In Vivo Dosimetry Algorithms.
- Authors
Esposito, Marco; Marrazzo, Livia; Vanzi, Eleonora; Russo, Serenella; Pallotta, Stefania; Talamonti, Cinzia
- Abstract
Featured Application: Transit dosimetry, with Electronic Portal Imaging Device (EPID), is a powerful tool for in vivo dosimetry (IVD). Despite its wide availability and its simplicity of use, the clinical implementation of such a dosimetric technique is still challenging. One reason for the difficulty of IVD implementation is the lack of guidelines around the validation and acceptance of EPID IVD algorithms. In this paper we propose an evaluation method for assessing the accuracy of a novel 3D EPID back-projection algorithm for IVD. To the best of our knowledge, the EPID back-projection algorithms have never been validated in anthropomorphic phantom against direct two-dimensional measurements, and the new algorithm, introduced in version 5.8 of the Dosimetry Check software for dealing with tissue inhomogeneity, has never been evaluated before. The aim of this study was to develop and apply an evaluation method for assessing the accuracy of a novel 3D EPID back-projection algorithm for in vivo dosimetry. The novel algorithm of Dosimetry Check (DC) 5.8 was evaluated. A slab phantom homogeneously filled, or with air and bone inserts, was used for fluence reconstruction of different squared fields. VMAT plans in different anatomical sites were delivered on an anthropomorphic phantom. Dose distributions were measured with radiochromic films. The 2D Gamma Agreement Index (GAI) between the DC and the film dose distributions (3%, 3 mm) was computed for assessing the accuracy of the algorithm. GAIs between films and TPS and between DC and TPS were also computed. The fluence reconstruction accuracy was within 2% for all squared fields in the three slabs' configurations. The GAI between the DC and the film was 92.7% in the prostate, 92.9% in the lung, 96.6% in the head and the neck, and 94.6% in the brain. An evaluation method for assessing the accuracy of a novel EPID algorithm was developed. The DC algorithm was shown to be able to accurately reconstruct doses in all anatomic sites, including the lung. The methodology described in the present study can be applied to any EPID back-projection in vivo algorithm.
- Subjects
RADIATION dosimetry; ALGORITHMS; EVALUATION methodology
- Publication
Applied Sciences (2076-3417), 2021, Vol 11, Issue 22, p10715
- ISSN
2076-3417
- Publication type
Article
- DOI
10.3390/app112210715