Purpose: To investigate the clinical application of position calibration function of Octavius®‐4D dose verification system in three-dimensional radiotherapy dose verification.
Methods: 208 cases were selected retrospectively, whose were divided into two kinds of groups: one is by the body regions, head and neck, chest, abdomen，breast; and the other is by the accelerator types. It is used to investigate the influence of three-dimensional dose passing rate using position calibration function. The cutoff value method provided by ROC curve is used to find the threshold of shifting value in three-dimensional direction in the dose passing rate.
Results: The overall passing rate is significantly higher basing on Max dose standard than Local dose standard. According to body regions, before calibration, the dose passing rate of the head and neck is highest, and the breast is worst, it is more obvious using local dose standard. After calibration, the region of the highest passing rate is abdomen, and the lowest is head and neck(Max dose standard) and breast(Local dose standard). According to accelerator types: before calibration, the highest passing rate based on Max dose standard is Triligy, followed by Edge and Truebeam; the highest based on Local dose standard is Truebeam, followed by Edge and Trilogy. ROC analysis: taking Max31(based on Max dose standard) as end event, the cutoff value in shift0(left and right) direction is 0.39(P=0.0001), and the cutoff value in shift1(head and foot) direction is -0.66(P=0.22); meaningless cutoff value is found in shift2(up and down).Taking Max30(Max dose standard) as the final event, the only meaningful direction is shift2, and the cutoff value is -0.21(P=0.0034).
Conclusion: The position calibration function of Octavius®‐4D dose verification system is effective in three-dimensional dose verification, which is influent on different body regions, accelerator types and position accuracy. It can improve the passing rate and has high clinical value.
Treatment Verification, Quality Assurance, 3D