  Although sparse-view computed tomography (CT) has significantly reduced
radiation dose, it also introduces severe artifacts which degrade the image
quality. In recent years, deep learning-based methods for inverse problems have
made remarkable progress and have become increasingly popular in CT
reconstruction. However, most of these methods suffer several limitations:
dependence on high-quality training data, weak interpretability, etc. In this
study, we propose a fully unsupervised framework called Deep Radon Prior (DRP),
inspired by Deep Image Prior (DIP), to address the aforementioned limitations.
DRP introduces a neural network as an implicit prior into the iterative method,
thereby realizing cross-domain gradient feedback. During the reconstruction
process, the neural network is progressively optimized in multiple stages to
narrow the solution space in radon domain for the under-constrained imaging
protocol, and the convergence of the proposed method has been discussed in this
work. Compared with the popular pre-trained method, the proposed framework
requires no dataset and exhibits superior interpretability and generalization
ability. The experimental results demonstrate that the proposed method can
generate detailed images while effectively suppressing image
artifacts.Meanwhile, DRP achieves comparable or better performance than the
supervised methods.
