Study on setting of tolerance and action limits based on gamma passing rate and consistency for SunCHECK and ArcCHECK

Objective To clarify the differences in tolerance limits and action limits set by the two systems for dose verification, as well as the consistency of gamma passing rates between them, by comparing the gamma passing rate, dose deviation, and related parameters of the SunCHECK and ArcCHECK dose verification systems in intensity modulated radiotherapy (IMRT).Methods A total of 71 patients with head and neck tumors, thoracic tumors, and abdominal-pelvic tumors who underwent IMRT were retrospectively included and analyzed. Based on the gamma passing rate, the tolerance limits and action limits for different groups were calculated. The volumetric dose deviation of the target volume and organs at risk, as well as their Pearson correlation with the gamma passing rate, were analyzed. Additionally, the consistency of the gamma passing rate between the two systems was assessed using the Bland-Altman method.Results Under the 3%/3 mm and 3%/2 mm criteria, the differences in gamma passing rates between the two systems were relatively small, and the biases in the Bland-Altman analysis all fell within the 95% confidence interval. However, under the 2%/2 mm criteria, significant differences in gamma passing rates were observed between the thoracic tumor group and the abdominal-pelvic tumor group, and the consistency exceeded the 95% confidence interval. Under the 3%/2 mm criteria, the head and neck group and abdominal-pelvic group had tolerance limits≥95.27% and action limits≥93.52%, while the thoracic group had tolerance limits≥93.90% and action limits≥90.92%. Strong negative correlations (r=-0.43 to -0.77, P<0.05) were identified between the volumetric dose deviation of the target volume and the gamma passing rate for SunCHECK. Conversely, the correlation between the volumetric dose deviation of organs at risk and the gamma passing rate was inconsistent, with overall results indicating either weak or no significant correlation.Conclusions SunCHECK and ArcCHECK demonstrated high consistency under 3%/3 mm and 3%/2 mm criteria. Additionally, the dynamic adjustment of the setting of tolerance and action limits based on anatomical locations, as well as evaluation of deviation in volumetric dosimetry parameters, is crucial for optimizing the patient-specific quality assurance process.