Abstract： Objective To investigate the feasibility of detector array in Monaco modeling for MLC parameters adjustment. Methods One parameter was fixed, and then the other parameter was changed. The γ pass rates of the test beams, namely 3ABUT, 7SegA, and FOUR L, were assessed to determine the values of leaf transmission and leaf offset. A total of 12 tumor cases from different anatomical sites were randomly selected. Two-dimensional dose verification (rack angle zero) of Step& Shot and dMLC plans as well as three-dimensional dose validation of VMAT plan were performed using Octavius 4D system. The γ pass rates were analyzed at a standard of 3%/3 mm. Meanwhile, the point dose verification for these three plans was analyzed to obtain the dose deviations. Results The values of leaf transmission and leaf offset were 0.0105 and-0.08 mm, respectively. The average γ pass rates (%) of Step& Shot, dMLC, and VMAT plans were 88.59±2.94, 87.81±3.28, and 87.45±2.24 before adjustment and 98.45±1.23, 98.9±1.01, and 96.03±1.66 after adjustment. In addition, the average dose deviations (%) according to the point dose verification were 0.85±0.75, 0.95±0.39, and 0.98±0.40 before adjustment and 0.97±0.57, 1.08±0.76, and 0.86±0.45 after adjustment. Conclusions Octavius detector 729 ionization chamber array is a feasible and reliable device in Monaco modeling for MLC parameters adjustment.
Niu Zhenyang,Fei Zhenle,Duan Zongjin et al. Application of detector array in treatment planning system modeling adjustment[J]. Chinese Journal of Radiation Oncology, 2017, 26(7): 806-809.
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