title: Investigation of an optimized scanning protocol for the dentomaxillofacial region using 320-slice multidetector computed tomography.
abstract: OBJECTIVE
  To propose an imaging protocol that provides satisfactory image quality for oral examination while minimizing radiation dosage using 320-slice multidetector CT (MDCT).
  
  
  METHODS
  An anthropomorphic head phantom was scanned using 320 MDCT with protocols combining different scanning modes: volume scanning (whole or local) vs helical scanning (80- or 64-slice detectors); tube voltage settings (80 kVp, 120 kVp and 135 kVp); and tube current settings (60 mA, 80 mA, 100 mA and 120 mA). A total of six anatomical bone structures and three anatomical soft-tissue structures were assessed using quantitative and qualitative analysis in the three orthographic planes (axial, sagittal and coronal). A figure of merit (FOM) was used to determine the optimal imaging protocol in terms of tube voltage, tube current and scanning mode.
  
  
  RESULTS
  The 80-kVp setting had the worst quantitative and qualitative results (both p < 0.001) compared with the 135-kVp and 120-kVp settings, especially for soft-tissue structures. A significant difference was noted for the scores obtained using a tube current between 120 mA and 60 mA by quantitative analysis, but not by qualitative analysis. Volume scans using either whole or local modes had a significantly higher FOM than helical scanning of 80 or 64 slices.
  
  
  CONCLUSIONS
  In 320 MDCT, a protocol using 135 kVp, 80 mA and the volume-scanning mode (whole or local) offers adequate visualization of both soft-tissue and bone structures while keeping the radiation dose as low as possible. This may therefore be considered a first choice among a wide selection of scanning protocols for dentomaxillofacial CT.
authors.affiliation: 1 Department of Radiology, Cathay General Hospital, Taipei, Taiwan.|2 School of Medicine, Fu-Jen Catholic University, New Taipei City, Taiwan.
authors.forename: Wei-Chan
authors.initials: WC
authors.lastname: Lin
authors.affiliation: 3 Department of Radiology, National Yang-Ming University Hospital, Yilan City, Taiwan.
authors.forename: Hsueh-Han
authors.initials: HH
authors.lastname: Wang
authors.affiliation: 4 School of Medicine, Tzu-Chi University, Hualien, Taiwan.|5 Department of Radiation Oncology, Buddhist Tzu-Chi General Hospital, Hualien, Taiwan.
authors.forename: Wen-Lin
authors.initials: WL
authors.lastname: Hsu
authors.affiliation: 6 Department of Radiology, Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
authors.forename: Bi-Hui
authors.initials: BH
authors.lastname: Cao
authors.affiliation: 6 Department of Radiology, Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
authors.forename: De-Ji
authors.initials: DJ
authors.lastname: Chen
authors.affiliation: 7 Department of Medical Imaging and Radiological Sciences, Chung Shan Medical University, Taichung, Taiwan.
authors.forename: Chia-Jung
authors.initials: CJ
authors.lastname: Tsai
mesh_terms: D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D061330:Multidetector Computed Tomography / Q000379:methods*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011861:Radiography, Dental / Q000379:methods*
keywords: dental imaging; dentomaxillofacial CT; image quality; radiation dose