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Clinical Implementation of a Model-Based In Vivo Dose Verification System for Stereotactic Body Radiation Therapy-Volumetric Modulated Arc Therapy Treatments Using the Electronic Portal Imaging Device.

Clinical Implementation of a Model-Based In Vivo Dose Verification System for Stereotactic Body Radiation Therapy-Volumetric Modulated Arc Therapy Treatments Using the Electronic Portal Imaging Device.

Authors :
McCowan, Peter M.
Asuni, Ganiyu
Van Uytven, Eric
VanBeek, Timothy
McCurdy, Boyd M.C.
Loewen, Shaun K.
Ahmed, Naseer
Bashir, Bashir
Butler, James B.
Chowdhury, Amitava
Dubey, Arbind
Leylek, Ahmet
Nashed, Maged
Source :
International Journal of Radiation Oncology, Biology, Physics. Apr2017, Vol. 97 Issue 5, p1077-1084. 8p.
Publication Year :
2017

Abstract

<bold>Purpose: </bold>To report findings from an in vivo dosimetry program implemented for all stereotactic body radiation therapy patients over a 31-month period and discuss the value and challenges of utilizing in vivo electronic portal imaging device (EPID) dosimetry clinically.<bold>Methods and Materials: </bold>From December 2013 to July 2016, 117 stereotactic body radiation therapy-volumetric modulated arc therapy patients (100 lung, 15 spine, and 2 liver) underwent 602 EPID-based in vivo dose verification events. A developed model-based dose reconstruction algorithm calculates the 3-dimensional dose distribution to the patient by back-projecting the primary fluence measured by the EPID during treatment. The EPID frame-averaging was optimized in June 2015. For each treatment, a 3%/3-mm γ comparison between our EPID-derived dose and the Eclipse AcurosXB-predicted dose to the planning target volume (PTV) and the ≥20% isodose volume were performed. Alert levels were defined as γ pass rates <85% (lung and liver) and <80% (spine). Investigations were carried out for all fractions exceeding the alert level and were classified as follows: EPID-related, algorithmic, patient setup, anatomic change, or unknown/unidentified errors.<bold>Results: </bold>The percentages of fractions exceeding the alert levels were 22.6% for lung before frame-average optimization and 8.0% for lung, 20.0% for spine, and 10.0% for liver after frame-average optimization. Overall, mean (± standard deviation) planning target volume γ pass rates were 90.7% ± 9.2%, 87.0% ± 9.3%, and 91.2% ± 3.4% for the lung, spine, and liver patients, respectively.<bold>Conclusions: </bold>Results from the clinical implementation of our model-based in vivo dose verification method using on-treatment EPID images is reported. The method is demonstrated to be valuable for routine clinical use for verifying delivered dose as well as for detecting errors. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
03603016
Volume :
97
Issue :
5
Database :
Academic Search Index
Journal :
International Journal of Radiation Oncology, Biology, Physics
Publication Type :
Academic Journal
Accession number :
121781304
Full Text :
https://doi.org/10.1016/j.ijrobp.2017.01.227