Effects of high-resolution measurements between different multi-row detectors on volumetric modulated arc therapy patient-specific quality assurance

Background: This study aimed to evaluate the optimal criteria and conditions in which single-measurement (SM) and high-resolution measurement (HM) provide a similar evaluation accuracy for ArcCHECK (AC) and Octavius (OT) detectors. Materials and Methods: In the SM and HM for AC and OT, we evaluated & gamma;-analysis pass-rate differences for various conditions (criteria, calculation grid size, and shift of the isocenter) of 20 patients who received volumetric modulated arc therapy. All results of the & gamma;-analysis pass rate were analyzed using the Anderson-Darling normality test. Results: In the AC detector, an SM with a 1%/1 mm criterion, 1.25 mm calculation grid size, and two standard deviations (2SD) of tolerance showed an evaluation accuracy similar to that of an HM. In the OT detector, an SM with a 2%/2 mm criterion, 2.0 mm calculation grid, and 2SD of tolerance had an evaluation accuracy similar to that of an HM. The & gamma;-pass-rate data of the OT detector for the 3%/3 mm criterion did not follow a normal distribution in both SM and HM. Conclusions: Most high & gamma;-analysis pass rates achieved using inadequate criteria may not detect errors; therefore, accurate evaluation is necessary for optimizing the criteria settings of individual QA devices based on the characteristics and the uncertainties of array detectors. The characteristics of a detector array can be enhanced by evaluating the relationship between SM and HM, which reduces the workload of patient-specific QA.