Evaluation of EPID-based Dose Verification System for a New Elekta LINAC: A Preliminary Study
Presentation given during the 10th Japan-Korea Joint Meeting on Medical Physics on Performance evaluation of RadCalc EPID for a new Elekta Harmony Pro LINAC
Abstract
Purpose
Recently, many radiation oncology departments have been using calculation-based patient-specific quality assurance (PSQA) systems to verify treatment plans, but implementing new LINAC equipment into the system requires extensive validation in clinical practice. This study aims to evaluate the performance of the RadCalc EPID (LAP GmbH) for a new Elekta LINAC machine, Harmony Pro.
Method
The 6 MV and 6 MV FFF (flattening filter free) photon beams of the Harmony Pro were modeled in RadCalc EPID software using measured beam data. To evaluate RadCalc EPID performance, dosimetric tests were conducted, including percent depth dose, beam profiles, and beam output factors for field sizes (5 × 5, 10 × 10, and 30 × 30 cm²). A total of 29 patient-specific plans (19 for 6 MV and 10 for 6 MV FFF) at various disease sites were mapped in an ArcCheck® phantom (Sun Nuclear) and recalculated in both TPS and RadCalc EPID. The dose distributions were compared using gamma analysis with 3 mm/3% criteria and a minimum pass rate of 90%.
Results
The gamma analysis results of the photon beams dosimetric test demonstrated passing rates of 98.84% at 2 mm/2% criteria. For the dose distribution comparison between TPS and RadCalc EPID, in the case of 6 MV, 16 out of 19 patients exceeded the minimum passing rate of 90% with an average of 91.13% based on 3 mm/3% criteria. Although the remaining 3 patients did not meet the passing rate, their average was still high at 89.21%. For 6 MV FFF, all 10 patients exceeded the minimum passing rate of 90%, achieving an average passing rate of 98.78% based on the 3 mm/3% criteria.
Conclusion
We evaluated the RadCalc EPID dose calculation system with Harmony, achieving a gamma passing rate of at least 92.49% at 3 mm/3% criteria. This performance test confirmed that the system meets the 3 mm/3% gamma passing rate criteria. Future studies will validate VMAT treatment plans using measurement data and portal images in RadCalc EPID.
Reference
Dohyeon Yoo, Hyunggun Lee, Sangmin Lee, Soorim Han, Taeho Kim, Changhwan Kim, Min Cheol Han*, and Jin Sung Kim
Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine & Heavy Ion Therapy Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
The findings were presented during the 10th Japan-Korea Joint Meeting on Medical Physics JKMP10, https://jkmp2024.com/