A novel high order directional total variation algorithm of EPR imaging for fast scan

BackgroundPulsed Electron paramagnetic resonance (EPR) imaging (EPRI) is an advanced oxygen imaging modality for precision radiotherapy, typically acquires high signal-to-noise ratio (SNR) data by averaging the repeatedly collected projections at the corresponding angle to suppress the random noise. This scan mode is the reason for the slow scan speed. The present mitigation is to reduce the repetition times (termed 'shots') for each projection, which leads to noisy projections.ObjectiveAlthough the directional total variation (DTV) algorithm could reconstruct the image from these noisy projections, it may appear staircase artifacts. To solve this problem, we further propose a novel high order DTV (HODTV) algorithm for fast 3D pulsed EPRI.MethodsThe HODTV model has introduced the regularization of high order derivatives, in which the objective term and the high order derivate regularization aim for data fidelity and detail recovery, respectively. Then, we derive its Chambolle-Pock (CP) solving algorithm and verify the correctness. To evaluate the HODTV algorithm, both qualitative and quantitative results are performed with real-world data.ResultsCompared with the filtered back projection (FBP), total variation (TV), and DTV algorithms, the results demonstrate that our method can achieve higher accurate reconstruction. In specific cases, our algorithm only requires 100 shots of scan acquisitions in $\sim$6 seconds, whereas the FBP algorithm needs 2000 shots of scan acquisitions taking $\sim$120 seconds.ConclusionsThe practical development of clinical imaging workflow, including but not limited to fast 3D pulsed EPRI, may make use of our work.