Figure 1.

Workflow of voxel-wise population-based analysis. This workflow comprises five steps: (1) synthetic CT (sCT) generation with bulk-density and generative adversarial network (GAN) methods, (2) dose calculation and (3) error evaluation of images and doses in the native space of each patient. This evaluation includes the computation of absolute error, error, and absolute percent error. The non-rigid registration step (4) resulted in deformation fields, allowing for propagation of the whole data to a common coordinate system. Once all data were in the same anatomical space, statistical analysis was performed (5), producing three-dimensional (3D) error maps for each sCT generation method and highlighting significant difference subregions for both image and dose distributions.