CNN-based projected gradient descent for consistent CT image reconstruction

H Gupta, KH Jin, HQ Nguyen… - IEEE transactions on …, 2018 - ieeexplore.ieee.org
IEEE transactions on medical imaging, 2018ieeexplore.ieee.org
We present a new image reconstruction method that replaces the projector in a projected
gradient descent (PGD) with a convolutional neural network (CNN). Recently, CNNs trained
as image-to-image regressors have been successfully used to solve inverse problems in
imaging. However, unlike existing iterative image reconstruction algorithms, these CNN-
based approaches usually lack a feedback mechanism to enforce that the reconstructed
image is consistent with the measurements. We propose a relaxed version of PGD wherein …
We present a new image reconstruction method that replaces the projector in a projected gradient descent (PGD) with a convolutional neural network (CNN). Recently, CNNs trained as image-to-image regressors have been successfully used to solve inverse problems in imaging. However, unlike existing iterative image reconstruction algorithms, these CNN-based approaches usually lack a feedback mechanism to enforce that the reconstructed image is consistent with the measurements. We propose a relaxed version of PGD wherein gradient descent enforces measurement consistency, while a CNN recursively projects the solution closer to the space of desired reconstruction images. We show that this algorithm is guaranteed to converge and, under certain conditions, converges to a local minimum of a non-convex inverse problem. Finally, we propose a simple scheme to train the CNN to act like a projector. Our experiments on sparse-view computed-tomography reconstruction show an improvement over total variation-based regularization, dictionary learning, and a state-of-the-art deep learning-based direct reconstruction technique.
ieeexplore.ieee.org
Showing the best result for this search. See all results