Room: Exhibit Hall | Forum 1
Purpose: To simulate a Cone-beam CT (CBCT) image with the help of 3D surface imaging in the Surface Guided Radiation Therapy (SGRT).
Methods: The 3D surface imaging system (Intel RealSense R200 Camera) installed in the treatment room to facilitate CBCT guided radiotherapy, and a silicone breast phantom was scanned. The surface based deformable image registration (SurDIR) and finite element method (FEM) based simulation were combined for CBCT image simulation of a silicone breast phantom. Firstly, the 3D surface camera extracts the surface image of the original phantom and the deformed phantom caused by artificially exerting external force. Both the original and deformed phantom were scanned using CBCT named as CBCT1 and CBCT2. Secondly, SurDIR was performed between two shapes of surface images, which yield the surface displacement vector field (DVFsur), DVFsur is the multifreedom constraints and used as boundary conditions for FEM. Then a tetrahedron mesh was generated through the outer contour of the CBCT1 with the parameters (size 3ï¼Œfidelity 1), and initialized by the DVFsur, the mesh was deformed by the FEM solver, which yield the mesh DVF (DVFmesh). And the CBCTsim was generated from the deformation of CBCT1 with the help of DVFmesh. Finally, the performance of the simulation was assessed by comparing the CBCT2 in 5 different deformations of breast phantom.
Results: The proposed simulation method was assessed by dice similarity coefficient (DSC) to measure similarity between the CBCTsim and CBCT1. Compared with CBCT2, the average and discrepancies of DSC was found to be 94.1%Â±2.1%.
Conclusion: In this work, we proposed an effective breast CBCT simulation method cooperative with 3D surface image, which ensure patient positioning without an additional delivery of imaging dose during the radiotherapy treatment.
Funding Support, Disclosures, and Conflict of Interest: This work was funded by the National Natural Science Foundation of China (NO. 61471226), Natural Science Foundation for Distinguished Young Scholars of Shandong Province (NO. JQ201516), and the Taishan scholar project of Shandong Province.