title: Dose optimization for assessment of periodontal structures in cone beam CT examinations.
abstract: OBJECTIVE
  To investigate the relationship between dose and image quality for a dedicated dental CBCT scanner using different scanning protocols and to set up an optimal imaging protocol for assessment of periodontal structures.
  
  
  METHODS
  Radiation dose and image quality measurements were made using 3D Accuitomo 170 (J. Morita, Kyoto, Japan) dental CBCT scanner. The SedentexCT IQ phantom was used to investigate the relationship between contrast-to-noise ratio (CNR) and dose-area product. Subjective image quality assessment was achieved using a small adult skull phantom for the same range of exposure settings. Five independent observers assessed the images for three anatomical landmarks using a three-point visual grade analysis.
  
  
  RESULTS
  When correlating the CNR of each scanning protocol to the exposure parameters used to obtain it, CNR decreased as these parameters decreased, especially current-exposure time product. When correlating to subjective image quality, the CNR level remained acceptable when 5 mA and 17.5 s or greater was selected and 80 kV could be used without compromising the CNR.
  
  
  CONCLUSIONS
  For a dedicated CBCT unit, changing the rotation angle from 360° to 180° degrades image quality. By altering tube potential and current for the 360° rotation protocol, assessment of periodontal structures can be performed with a smaller dose without substantially affecting visualization.
authors.affiliation: 1 Department of Oral and Maxillofacial Radiology, Faculty of Odontology, Malmö University, Malmö, Sweden.|2 Department of Oral Medicine and Radiology, Faculty of Dentistry, Sebha University, Sebha, Libya.
authors.forename: Ayman
authors.initials: A
authors.lastname: Al-Okshi
authors.affiliation: 3 Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK.
authors.forename: Chrysoula
authors.initials: C
authors.lastname: Theodorakou
authors.affiliation: 4 Faculty of Odontology, Malmö University, Malmö, Sweden.
authors.forename: Christina
authors.initials: C
authors.lastname: Lindh
mesh_terms: D054893:Cone-Beam Computed Tomography / Q000379:methods*; D006801:Humans; D015588:Observer Variation; D010519:Periodontium / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods
keywords: CBCT; imaging; periapical tissue; phantoms; radiation dosage; three-dimensional imaging