Purpose: The RapidArc technique requires sophisticated treatment plan optimization and beam delivery technology. This work investigates the capabilities of the ArcCheck dosimetry system for RapidArc treatment planning verification and Linac dose delivery validation. Methods: A total of 10 (6 prostate, H&N, pelvis, liver and breast) clinical RapidArc treatment cases were investigated using a delivery QA procedure with the use of the ArcCheck dosimetry system. A custom acrylic plug with the ability to host an ion chamber was used for CAX phantom dose measurements. In addition to the Eclipse TPS, the treatment dose distributions were simulated using a Monte Carlo code in order to compare and evaluate the dose delivery based on the treatment plan. In both ways the distributions were evaluated in terms of the absolute dose and distance to agreement on a cylindrical plane dose distribution that overlaps with the ArcCheck detector plane. The system sensitivity to setup misalignment errors, and field size dependency, were also investigated. Results: Excluding the H&N case, the difference between calculated to measure absolute CAX dose was less than 3%. The H&N CAX fell on a dose distribution gradient, and hence showed a 6.6% and 7.1% dose difference, respectively, between the measurement dose and that calculated by the TPS and Monte Carlo. Gamma analysis passing rate varied from 92.8% for the pelvis case, and 98.8% for a prostate case, when using the 3% dose difference and 3mm distance to agreement criteria for the TPS dose distributions. A field‐size dependence was found for large field sizes (above 21 × 21 cm2). Conclusions: The ArcCheck dosimetry system showed good capabilities for RapidArc plan verification and dose delivery validation, with respect to the CAX dose and the overall dose distribution. The system sensitivity to setup misalignment and dose variation is demonstrated for the clinical cases investigated.
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging