  In this paper, the Primal-Dual UNet for sparse view CT reconstruction is
modified to be applicable to cone beam projections and perform reconstructions
of entire volumes instead of slices. Experiments show that the PSNR of the
proposed method is increased by 10dB compared to the direct FDK reconstruction
and almost 3dB compared to the modified original Primal-Dual Network when using
only 23 projections. The presented network is not optimized wrt. memory
consumption or hyperparameters but merely serves as a proof of concept and is
limited to low resolution projections and volumes.
