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Iterative Image-Domain Ring Artifacts Removal in Cone-Beam CT

X Liang

X Liang*, Z Zhang , S Yu , S Wu , Z Li , T Niu , Y Xie , Zhe Jiang University, Hang Zhou, Zhe Jiang


SU-H4-GePD-I-1 (Sunday, July 30, 2017) 4:30 PM - 5:00 PM Room: Imaging ePoster Lounge

Purpose: Ring artifacts in cone beam computed tomography (CBCT) images are caused by pixel gain variations in using flat panel detectors. It may lead to structured non-uniformities and deterioration of the image quality. The purpose of this study is to propose a novel and general ring artifact removal framework to eliminate ring artifacts in CBCT images.

Methods: The method is based on the polar coordinate system where the ring artifacts perform as the stripe artifacts. Using relative total variation (RTV), the CBCT image is first smoothed to construct a template image with less images details and ring artifacts. Then by subtracting the template from the CBCT image, the residual image with image details and ring artifacts is generated. As the ring artifacts perform as the stripe artifact in polar coordinate, the artifact image can be extracted by mean value from the residual image, the image details are generated by subtracting artifact image from residual image. Finally, the image details are compensated to the template image to generate a corrected image. The proposed scheme is iterated until the variation of the extracted ring artifacts is minimized.

Results: The proposed method is evaluated using 3D Shepp-Logan phantom, a Catphan©504 phantom, a uniform acrylic cylinder and a head patient. In the experiments of simulate data, the proposed method increases the spatial uniformity by a factor of 1.68 and increases the structural similarity index (SSIM) from 89.19% to 96.03%.

Conclusion: In the experiment of clinical data, our method shows high efficiency for ring artifacts removal, while the image structures and details are well preserved. In this work, we propose an iterative approach of ring artifact removal in cone-beam CT. The method is practical and attractive for CBCT guided radiation therapy.

Funding Support, Disclosures, and Conflict of Interest: This work is supported in part by grants from Guangdong Innovative Research Team Program of China (Grant No. 2011S013), National Key Research and Develop Program of China (Grant No. 2016YFC0105102), National 863 Programs of China (Grant Nos. 2012AA02A604 and 2015AA043203), Beijing Center for Mathematics and Information Interdisciplinary Sciences, Zhejiang Provincial Natural Science Foundation of China (Grant No. LR16F010001), National High-tech R&D Program for Young Scientists by the Ministry of Science and Technology of China (Grant No. 2015AA020917), National Key Research Plan by the Ministry of Science and Technology of China (Grant No. 2016YFC0104507) and Natural Science Foundation of China (NSFC Grant No. 81201091).

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