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Background: Acuros XB (AXB) is a novel algorithm implemented to the commercial vender of Varian Eclipse treatment planning system. It is developed to improve the accuracy of dose calculation in external beam radiotherapy, especially in heterogeneity region.
Objectives: To evaluate dosimetric impact of AXB algorithm in basic beam characteristics and clinical applications according to IAEA TRS 430 protocol.
Materials and methods: Scanning percentage depth doses (PDDs) from CC13 ionization chamber and beam profiles at 10 cm depth from PFD diode of 6 MV from TrueBEAM linear accelerator were obtained in water phantom. Output factors were measured at 10 cm depth using CC13 chamber. Doses of fifteen cases in each 3D-CRT, IMRT, and VMAT techniques in solid phantom and CIRS thorax phantom were measured with CC13 chamber. All measurement results were compared with calculation from Eclipse treatment planning system (TPS) using AXB algorithm.
Results: The results showed good agreement between measured and calculated PDDs with δ1 (high dose & small dose gradient) less than 1.5% and δ2 (high dose & large dose gradient) within 1.5 mm. Measured profiles also displayed the coincidence results with TPS, which showed δ2 less than 2 mm, δ3 (high dose & small dose gradient) within 3%, δ4 (low dose & small dose gradient) within 3%, and δ50-90 within 2 mm as the recommendation from IAEA TRS 430 protocol. Maximum output factors differences were only -1.54%. Clinical plans exhibited the dose differences between measurement and calculation in 3D-CRT, IMRT, and VMAT of -0.12±0.38%, -1.59±0.93%, and 0.87±1.24% for homogeneous phantom and 0.27±0.29%, -0.60±1.05%, and -1.12±0.44% for inhomogeneous phantom, respectively.
Conclusion: Dose differences between measurement and AXB algorithm calculation are within the recommendation of IAEA TRS 430. AXB algorithm is acceptable for dose calculation in external beam radiotherapy.
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