  Model based iterative reconstruction (MBIR) algorithms for low-dose X-ray CT
are computationally expensive. To address this problem, we recently proposed a
deep convolutional neural network (CNN) for low-dose X-ray CT and won the
second place in 2016 AAPM Low-Dose CT Grand Challenge. However, some of the
texture were not fully recovered. To address this problem, here we propose a
novel framelet-based denoising algorithm using wavelet residual network which
synergistically combines the expressive power of deep learning and the
performance guarantee from the framelet-based denoising algorithms. The new
algorithms were inspired by the recent interpretation of the deep convolutional
neural network (CNN) as a cascaded convolution framelet signal representation.
Extensive experimental results confirm that the proposed networks have
significantly improved performance and preserves the detail texture of the
original images.
