Related Experiment Video
Updated: Apr 15, 2026
10:33
Expedited Radiation Biodosimetry by Automated Dicentric Chromosome Identification ADCI and Dose Estimation
Published on: September 4, 2017
16.8K
Sensitivity and concordance study of an open source EPID-based linear accelerator test suite.
Lana C Critchfield1, Cory S Knill2, Ellie Durussel3
1Department of Radiation Oncology, University of Michigan, Wyoming, Michigan, USA.
Journal of Applied Clinical Medical Physics
|April 14, 2026
Summary
This study validates an electronic portal imaging device (EPID) test suite for linear accelerator (linac) quality assurance. The EPID suite effectively detects errors and aligns with traditional detectors for routine linac QA.
Area of Science:
- Medical Physics
- Radiation Oncology
- Quality Assurance
Background:
- Electronic portal imaging devices (EPIDs) offer efficient linear accelerator (linac) quality assurance (QA) but are underutilized beyond patient-specific IMRT QA.
- A multi-institutional consortium aims to standardize linac QA using a novel EPID-based test suite.
Purpose of the Study:
- To evaluate the sensitivity of an EPID test suite to intentional errors in linac parameters and treatment plans.
- To assess the concordance of the EPID test suite with linac performance fluctuations over time.
Main Methods:
- Tests were conducted on Varian TrueBeam and Clinac linacs, introducing specific errors to parameters like enhanced dynamic wedge (EDW) factors, central axis dose, focal spot alignment, beam symmetry, and leaf speeds.
- Measurements were performed using an EPID and analyzed by the test suite software, with comparisons made against ion chamber (IC) or array measurements.
- Concordance analysis over five months on a single linac assessed the suite's ability to track deviations during routine operations; measurement reproducibility was also evaluated.
Main Results:
- EPID measurements showed high agreement with IC/array, with differences typically within ±0.8% for central axis dose and <0.5% for EDW factors.
- The EPID suite demonstrated strong linearity for symmetry measurements (r > 0.99) and detected dose rate and MLC leaf speed variations within <0.4%.
- Concordance analysis revealed minimal average output differences (±0.3% to ±0.5%) and systematic symmetry differences with standard deviations <0.2%.
Conclusions:
- The EPID test suite demonstrates significant sensitivity in detecting intentional linac and plan errors.
- Results support the EPID test suite's capability for accurate linac commissioning and clinical integration.
- The study validates the EPID suite as a reliable tool for ongoing linac quality assurance and monitoring.
