Recommendations for dose calculations of lung cancer treatment plans treated with stereotactic ablative body radiotherapy (SABR)

17th International Conference on the Use of Computers in Radiation Therapy

物理学;计算机科学

Devpura, S.^1 ; Siddiqui, M.S.^1 ; Chen, D.^1 ; Liu, D.^1 ; Li, H.^1 ; Kumar, S.^1 ; Gordon, J.^1 ; Ajlouni, M.^1 ; Movsas, B.^1 ; Chetty, I.J.^1

Henry Ford Health System, Detroit MI 48202, United States^1

关键词: Anisotropic analytical algorithms;    Convolution/superposition;    Correlation coefficient;    Dose distributions;    Equivalent path lengths;    Model-based algorithms;    Pencil beam algorithms;    Treatment planning;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/489/1/012007/pdf
DOI  :  10.1088/1742-6596/489/1/012007

学科分类：计算机科学（综合）

来源: IOP

【 摘 要 】

The purpose of this study was to systematically evaluate dose distributions computed with 5 different dose algorithms for patients with lung cancers treated using stereotactic ablative body radiotherapy (SABR). Treatment plans for 133 lung cancer patients, initially computed with a 1D-pencil beam (equivalent-path-length, EPL-1D) algorithm, were recalculated with 4 other algorithms commissioned for treatment planning, including 3-D pencil-beam (EPL-3D), anisotropic analytical algorithm (AAA), collapsed cone convolution superposition (CCC), and Monte Carlo (MC). The plan prescription dose was 48 Gy in 4 fractions normalized to the 95% isodose line. Tumors were classified according to location: peripheral tumors surrounded by lung (lung-island, N=39), peripheral tumors attached to the rib-cage or chest wall (lung-wall, N=44), and centrally-located tumors (lung-central, N=50). Relative to the EPL-1D algorithm, PTV D95 and mean dose values computed with the other 4 algorithms were lowest for lung-island tumors with smallest field sizes (3-5 cm). On the other hand, the smallest differences were noted for lung-central tumors treated with largest field widths (7-10 cm). Amongst all locations, dose distribution differences were most strongly correlated with tumor size for lung-island tumors. For most cases, convolution/superposition and MC algorithms were in good agreement. Mean lung dose (MLD) values computed with the EPL-1D algorithm were highly correlated with that of the other algorithms (correlation coefficient =0.99). The MLD values were found to be ∼10% lower for small lung-island tumors with the model-based (conv/superposition and MC) vs. The correction-based (pencil-beam) algorithms with the model-based algorithms predicting greater low dose spread within the lungs. This study suggests that pencil beam algorithms should be avoided for lung SABR planning. For the most challenging cases, small tumors surrounded entirely by lung tissue (lung-island type), a Monte-Carlo-based algorithm may be warranted.