An Analysis of Quality Assurance for Intensity-modulated Radiation Therapy and Volumetric Modulated Arc Therapy Treatment Plans Using Two Dosimetric Methods: The arcCHECK System and EPIbeam Based Dosimetric Approach
Ajay Katake, Lalit Kumar, Balbir Singh, Amit Sharma, Deepak BasandraiAim:
The current study is to assess and compare the performance of an electronic portal imaging device (EPID)-based dosimetry system electronic portal imaging beam (EPIbeam) and a three-dimensional (3D) diode array system (ArcCHECK) using various gamma criteria (3%/3 mm, 2%/2 mm, 3%/2 mm and 1%/1 mm) in verifying intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans at different anatomical sites.
Materials and Methods:
A total of 100 clinical IMRT and VMAT treatment plans covering head and neck (HN), thoracic and pelvic sites were considered for patient specific quality assurance (PSQA). All the plans were calculated with the Monaco TPS (v6.1.4.0) and were treated with an Elekta Infinity linear accelerator with 6 MV photon beams. EPID-based portal dosimetry (EPIbeam, DosiSoft) and ArcCHECK (Sun Nuclear Corporation) were utilized to carry out PSQA. All plans were analyzed using global gamma with 10% dose threshold and 95% pass-rate.
Results:
A 3%/3 mm, EPID showed almost perfect pass rates (99.48%–100%) in HN, Thoracic, and Pelvic regions, and ArcCHECK was also close behind (97%–100%). EPID and ArcCHECK performed with a high level of accuracy (97.82–100 and 88.5%–98.8%, respectively) under stricter 2%/2 mm criteria. Using 3%/2 mm gamma criteria, EPID demonstrates higher pass rates (98.6%–100%), and ArcCHECK had also increased (93.2%–99.8%). In the most stringent 1%/1 mm, the performance of EPID declined moderately (77.28%–98.73%), and ArcCHECK had the lowest pass rates (61.6%–91.4%). In general, EPID exhibited better and more reproducible dose delivery accuracy in all conditions. The differences between the quality assurance (QA) systems were statistically significant (
Conclusion:
The PSQA systems EPID-based and ArcCHECK-based are valuable dosimetric verification of IMRT and VMAT. Their sensitivity and accuracy are emphasized by gamma analysis on several criteria. The EPID system offers Logistical advantage in clinical workflow, whereas ArcCHECK provides 3D dose verification. Both modalities are viable in clinical QA protocols.