(Sunday, 7/29/2018) 3:00 PM - 6:00 PM
Room: Exhibit Hall
Purpose: The study aimed to evaluate the dosimetric and biological impact of the dose calculation algorithm and the grid size in the treatment plan of volumetric modulated arc therapy (VMAT) for prostate cancer.
Methods: Twenty patients were included, and the treatment plans were initially generated with anisotropic analytical algorithm (AAA) and exported in difference dose grid and Acuros XB (AXB) algorithm. The AXB with 1, 2, and 3 mm dose grids, and the AAA with 1, 3, and 5 mm dose grids were applied. Dosimetric parameters such as homogeneity index (HI) and conformity index (CI),and biological parameters such as tumour control probability (TCP) and normal tissue complication probability (NTCP) were calculated.
Results: Significant differences were observed in the planning target volume (PTV) coverage (V95) between algorithms (p < 0.01), and the mean V95, HI, and CI using AAA were significantly affected by grid increase (p < 0.01). The TCP and NTCP of the AAA were higher than that of AXB (p < 0.01).
Conclusion: Compared with AXB with 1 mm grid, the AXB with 2 mm grid achieved comparable dose calculation accuracy with reasonable calculation time, and thus seems suitable for prostate VMAT therapy.
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