A prospect of verification on volumetric modulated arc therapy (VMAT) technique: SHANE phantom.

In Indonesia, approximately 40 percent of radiotherapy patient treatment uses advanced radiation treatment technologies. These technologies have improved the quality of radiation treatment, especially in head and neck cases, for that reason the research aims to analyze the verification methods using SHANE Phantom to improve the accuracy and precision of dose delivery to radiotherapy patients. This study used a CT image of the SHANE Phantom from the IAEA project in the dosimetry audit program which included delineation of the target and OAR. The method of this study evaluated end-to-end test treatment radiation for Volumetric Arc Therapy (VMAT) technique, starting from the pre-treatment planning which cover the output factor (OF) and profile and picket fence test on MLC, and then continuing the treatment planning evaluate the result of the target and OAR. In the end, the post-treatment planning is by doing QA plan which uses the IBA MatrixFFF and Octavious 4D phantom. The parameter agreement of gamma index analysis is 3%/3 mm and 10% threshold. For the profile dose evaluation, the highest difference is 0.2 cm in the cross-plane of Eclipse. The evaluation of the treatment planning for SHANE phantom result in the target using eclipse are 66 Gy (D98%), 66.7 Gy (D95%), 70.6 Gy (D50%), and 72.5 Gy (D2%) while in Monaco, the difference is only 1–2 Gy for PTV. It is because the Monte Carlo algorithm account for inhomogeneous medium and considering scatter. Furthermore, the dose constraint in all of the OAR is lower than the IAEA recommendation, with the assessment using the maximum or mean doses depending on the organs. Meanwhile, the gamma index measurement is 96.1% (Monaco) on Octavius and 98.7% (Eclipse 1) on matrixFFF. It can be drawn that SHANE Phantom can be implemented for the evaluation of the VMAT technique. [ABSTRACT FROM AUTHOR]