title: A comparative study of new and current methods for dental micro-CT image denoising.
abstract: OBJECTIVE
  The aim of the current study was to evaluate the application of two advanced noise-reduction algorithms for dental micro-CT images and to implement a comparative analysis of the performance of new and current denoising algorithms.
  
  
  METHODS
  Denoising was performed using gaussian and median filters as the current filtering approaches and the block-matching and three-dimensional (BM3D) method and total variation method as the proposed new filtering techniques. The performance of the denoising methods was evaluated quantitatively using contrast-to-noise ratio (CNR), edge preserving index (EPI) and blurring indexes, as well as qualitatively using the double-stimulus continuous quality scale procedure.
  
  
  RESULTS
  The BM3D method had the best performance with regard to preservation of fine textural features (CNREdge), non-blurring of the whole image (blurring index), the clinical visual score in images with very fine features and the overall visual score for all types of images. On the other hand, the total variation method provided the best results with regard to smoothing of images in texture-free areas (CNRTex-free) and in preserving the edges and borders of image features (EPI).
  
  
  CONCLUSIONS
  The BM3D method is the most reliable technique for denoising dental micro-CT images with very fine textural details, such as shallow enamel lesions, in which the preservation of the texture and fine features is of the greatest importance. On the other hand, the total variation method is the technique of choice for denoising images without very fine textural details in which the clinician or researcher is interested mainly in anatomical features and structural measurements.
authors.affiliation: 1 Biomaterials and Bioengineering, Faculty of Dentistry, University of Sydney, Sydney, Australia.
authors.forename: Mahdi
authors.identifier: http://orcid.org/0000-0003-0516-199X
authors.initials: M
authors.lastname: Shahmoradi
authors.affiliation: 2 Department of Biomedical Engineering, Faculty of Advanced Medical Technology, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Lashgari
authors.affiliation: 2 Department of Biomedical Engineering, Faculty of Advanced Medical Technology, Isfahan University of Medical Sciences, Isfahan, Iran.|3 Medical Image & Signal Processing Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Rabbani
authors.affiliation: 4 Department of Implantology, Stomatological Hospital, Jilin University, Changchun, Jilin, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Qin
authors.affiliation: 1 Biomaterials and Bioengineering, Faculty of Dentistry, University of Sydney, Sydney, Australia.|5 Department of Bio-clinical Sciences, Faculty of Dentistry, Health Sciences Centre, Kuwait University, Kuwait.
authors.forename: Michael
authors.initials: M
authors.lastname: Swain
mesh_terms: D000465:Algorithms; D016477:Artifacts; D003731:Dental Caries / Q000000981:diagnostic imaging; D003743:Dental Enamel / Q000000981:diagnostic imaging; D003804:Dentin / Q000000981:diagnostic imaging; D005374:Filtration / Q000295:instrumentation; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D008852:Microradiography / Q000379:methods; D011856:Radiographic Image Enhancement / Q000379:methods; D011861:Radiography, Dental / Q000379:methods*; D014056:Tomography, X-Ray / Q000379:methods; D014082:Tooth Fractures / Q000000981:diagnostic imaging; D055114:X-Ray Microtomography / Q000379:methods*
keywords: X-ray microtomography; computer-assisted image processing; dental; image quality enhancement; noise