Application of deformable image registration in adaptive radiotherapy for lung cancer

Abstract

Objective To evaluate the effect of different methods of deformable image registration on the dose evaluation in adaptive radiotherapy for lung cancer. Methods By using Raystation Ver4.5 treatment planning system platform, two algorithms (Hybrid-and Biomechanics-based deformable image registration) and two orders (CT images before and during radiotherapy as reference images) were adopted. Four deformable image registration methods were utilized to calculate the accumulative dose. Eleven patients of lung cancer received adaptive radiotherapy for 35.0-61.6 Gy were recruited. The mean doses of lung, heart and GTV and the D98 and D2 of GTV were statistically compared using four methods. Results With the four deformable image registration methods, the standard deviation of the mean lung dose of 11 lung cancer patients was ranged from 0.07 to 0.70 Gy, 0.01 to 0.79 Gy for the mean heart dose, 0.01 to 2.23 Gy for the mean GTV dose, 0.02 to 6.51 Gy for the D98 of GTV and 0.01 to 0.97 Gy for the D2 of GTV, respectively. Conclusion The selection of deformable image registration method causes uncertainty to the calculation of accumulative dose during adaptive radiotherapy for lung cancer. Key words: Deformable image registration; Lung neoplasms/adaptive radiotherapy