title: Applications of nonlocal means algorithm in low-dose X-ray CT image processing and reconstruction: A review.
abstract: Low-dose X-ray computed tomography (LDCT) imaging is highly recommended for use in the clinic because of growing concerns over excessive radiation exposure. However, the CT images reconstructed by the conventional filtered back-projection (FBP) method from low-dose acquisitions may be severely degraded with noise and streak artifacts due to excessive X-ray quantum noise, or with view-aliasing artifacts due to insufficient angular sampling. In 2005, the nonlocal means (NLM) algorithm was introduced as a non-iterative edge-preserving filter to denoise natural images corrupted by additive Gaussian noise, and showed superior performance. It has since been adapted and applied to many other image types and various inverse problems. This paper specifically reviews the applications of the NLM algorithm in LDCT image processing and reconstruction, and explicitly demonstrates its improving effects on the reconstructed CT image quality from low-dose acquisitions. The effectiveness of these applications on LDCT and their relative performance are described in detail.
authors.affiliation: Departments of Radiology and Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: School of Biomedical Engineering, Southern Medical University, Guangzhou, 510515, China.|Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, 510515, China.|Guangzhou Key Laboratory of Medical Radiation Imaging and Detection Technology, Guangzhou, 510515, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Zeng
authors.affiliation: School of Biomedical Engineering, Southern Medical University, Guangzhou, 510515, China.|Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, 510515, China.|Guangzhou Key Laboratory of Medical Radiation Imaging and Detection Technology, Guangzhou, 510515, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.affiliation: Departments of Radiology and Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794, USA.
authors.forename: Zhengrong
authors.initials: Z
authors.lastname: Liang
authors.affiliation: School of Biomedical Engineering, Southern Medical University, Guangzhou, 510515, China.|Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, 510515, China.|Guangzhou Key Laboratory of Medical Radiation Imaging and Detection Technology, Guangzhou, 510515, China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Ma
mesh_terms: D000465:Algorithms; D016477:Artifacts; D006801:Humans; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: X-ray CT; denoising; dose reduction; nonlocal means; streak artifacts; view-aliasing artifacts