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Purpose: Segmental scanning protocol of Multi-energy computed tomography(MECT)is an easy-to-implement and no-extra dose induced way realized in conventiaonal CT,but the reconstruced image was degraded by severe undersampled artifacts.To address the problem,we propose a joint Robust Principal Components Analysis(RPCA)and Total Variation(TV)constraint method(RPCA-TV).Methods: The RPCA-TV can utilize the structure correlation of multi-energy images as well as effectively preserve edge infomation.The proposed method consists of three steps: 1)Combine the segmental projections into reweighted projection and utilize filtered back-projection reconstruction method; 2)Perform TV minimization reconstruction(e.g.Q-TV)with a prior image; 3)Process to RPCA with the above reconstructed images.For the first step,the incomplete projections were combined into a whole reweighted projection,which utilize the prior knowledge that structure correlated between each energy and the whole spectrum data.The most important is that,RPCA decomposed image matrix into a low-rank portion and a sparse portion,which will distinguish spectral differences and further enhance data fidelity.The method is validated on simulated FORBILD head phantom.Results: In our experiments,three sets of 360 projections were scanned in one cycle by setting CT tube voltage as 80,100,and 140 kVp in each 120 degrees respectively.In the simulated case comparing with Q-TV,the RPCA-TV improved the SNR with 35dB by~2 times at 100 iterations.The convergent rate was increased by a factor of 2.5.The visual inspection can consistently find that the proposed RPCA-TV suppressed some limited-angle artifacts and made a better edge recovery.Conclusions: A joint RPCA and TV constraint method was proposed with superior reconstruction accuracy and image quality in Segmental scanning protocol of MECT.