Faculty, Staff and Student Publications
Language
English
Publication Date
10-1-2024
Journal
Physics and Imaging in Radiation Oncology
DOI
10.1016/j.phro.2024.100666
PMID
39624392
PMCID
PMC11609462
PubMedCentral® Posted Date
11-1-2024
PubMedCentral® Full Text Version
Post-print
Abstract
Background and purpose: With the availability of commercial electronic portal imaging detector-based in vivo dosimetry (EPID-based IVD) solutions, many radiotherapy departments are adopting this technology. However, comprehensive commissioning guidance is lacking. This study aims to provide a protocol for testing the accuracy and sensitivity of EPID-based IVD systems.
Material and methods: The protocol was tested across four institutions using two different systems. Accuracy was evaluated with homogeneous slab phantoms using different square regular fields, and clinical plans in a CIRS lung phantom. Multiple forward and back-projected algorithm implementations were assessed for different energies. Sensitivity analysis in the lung phantom examined responses to setup errors, anatomical variations, and delivery errors.
Results: In homogeneous phantoms, over 85 % of pixels passed the 5 %/2mm gamma criteria, except for the 2x2 cm2 field. In the lung phantom, all systems and implementations achieved over 95 %-pixel pass rates at the 2 %/2mm criterion for volumetric modulated arc therapy (VMAT) plans. For conformal radiation therapy (3DCRT) plans, one system implementation showed poor accuracy, with over 90 % agreement only at the 5 %/2mm criterion. Considering all systems and implementations, average sensitivity and specificity for CRT plans ranged from 0.92 and 0.42 (at 2 %/2mm) to 0.71 and 0.52 (at 5 %/2mm), while for VMAT plans ranged from 0.41 and 0.81 (at 2 %2mm) to 0.37 and 0.81 (at 5 %/2mm).
Conclusion: We successfully developed a protocol to commission EPID IDV systems. It was found that not all systems and implementations achieved satisfactory accuracy and sensitivity, emphasising the need for thorough commissioning and benchmarking.
Keywords
“In vivo” dose measurements, EPID, QA, Dosimetry
Published Open-Access
yes
Recommended Citation
Esposito, Marco; Baldoni, Riccardo; Bossuyt, Evy; et al., "A Commissioning Protocol for Portal Imaging-Based Radiotherapy In Vivo Dosimetry Systems" (2024). Faculty, Staff and Student Publications. 6041.
https://digitalcommons.library.tmc.edu/uthgsbs_docs/6041
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