SU‐E‐T‐48: A Multi‐Institutional Study of Independent Dose Verification for Conventional, SRS and SBRT

Abstract

Purpose:To show the results of a multi‐institutional study of the independent dose verification for conventional, Stereotactic radiosurgery and body radiotherapy (SRS and SBRT) plans based on the action level of AAPM TG‐114.Methods:This study was performed at 12 institutions in Japan. To eliminate the bias of independent dose verification program (Indp), all of the institutions used the same CT‐based independent dose verification software (Simple MU Analysis, Triangle Products, JP) with the Clarkson‐based algorithm. Eclipse (AAA, PBC), Pinnacle3 (Adaptive Convolve) and Xio (Superposition) were used as treatment planning system (TPS). The confidence limits (CL, Mean±2SD) for 18 sites (head, breast, lung, pelvis, etc.) were evaluated in comparison in dose between the TPS and the Indp.Results:A retrospective analysis of 6352 treatment fields was conducted. The CLs for conventional, SRS and SBRT were 1.0±3.7 %, 2.0±2.5 % and 6.2±4.4 %, respectively. In conventional plans, most of the sites showed within 5 % of TG‐114 action level. However, there were the systematic difference (4.0±4.0 % and 2.5±5.8 % for breast and lung, respectively). In SRS plans, our results showed good agreement compared to the action level. In SBRT plans, the discrepancy between the Indp was variable depending on dose calculation algorithms of TPS.Conclusion:The impact of dose calculation algorithms for the TPS and the Indp affects the action level. It is effective to set the site‐specific tolerances, especially for the site where inhomogeneous correction can affect dose distribution strongly.