Dosimetric impact of respiratory motion during boron neutron capture therapy for lung cancer

Lung cancer is one of the cancers with high morbidity and mortality. Boron neutron capture therapy (BNCT) has attracted researchers’ attention in recent years because of its unique advantages in lung cancer treatment. However, changes in dose distribution in BNCT due to respiratory motion have not been studied. In this work, the tumor dose deviation caused by respiration was quantitatively investigated. Four-dimensional Computed Tomography (4D CT) was used to construct the virtual respiratory patient model in this study. Six phases (e.g., 10%, 20%, 50%, 60%, 80%, and 90%) were selected to represent the anatomy of patients at different moments throughout the respiratory cycle. Tumor-related dose volume histograms (DVH) indices at different phases were calculated using Monte Carlo toolkit. The results showed that the dose difference increased with the increasing of respiratory motion amplitude. In the three movement directions of the tumor, the dose changes caused by the movement in the anterior–posterior (AP) direction were remarkable under the treatment planning configurations we studied. The differences of tumor mean dose ranged from −13.8% to 15.8%. Similar conclusions were observed in the cases of three real patients.