title: National Survey of Radiation Dose and Image Quality in Adult CT Head Scans in Taiwan.
abstract: BACKGROUND
  The purpose of the present study was to evaluate the influence of different variables on radiation dose and image quality based on a national database.
  
  
  METHODS
  Taiwan's Ministry of Health and Welfare requested all radiology departments to complete a questionnaire for each of their CT scanners. Information gathered included all scanning parameters for CT head scans. For the present analysis, CT machines were divided into three subgroups: single slice CT (Group A); multi-detector CT (MDCT) with 2-64 slices (Group B); and MDCT with more than 64 slices (Group C). Correlations between computed tomography dose index (CTDI) and signal-to-noise ratio (SNR) with cumulated tube rotation number (CTW(n)) and cumulated tube rotation time (CTW(s)), and sub group analyses of CTDI and SNR across the three groups were performed.
  
  
  RESULTS
  CTDI values demonstrated a weak correlation (r = 0.33) with CTW(n) in Group A. SNR values demonstrated a weak negative correlation (r = -0.46) with CTW(n) in Group C. MDCT with higher slice numbers used more tube potential resulting in higher effective doses. There were both significantly lower CTDI and SNR values in helical mode than in axial mode in Group B, but not Group C.
  
  
  CONCLUSIONS
  CTW(n) and CTW(s) did not influence radiation output. Helical mode is more often used in MDCT and results in both lower CTDI and SNR compared to axial mode in MDCT with less than 64 slices.
authors.affiliation: School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Chung-Jung
authors.initials: CJ
authors.lastname: Lin
authors.affiliation: Biomedical Imaging Laboratory, Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau, China.
authors.forename: Greta S P
authors.initials: GS
authors.lastname: Mok
authors.affiliation: Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei, Taiwan.
authors.forename: Mang-Fen
authors.initials: MF
authors.lastname: Tsai
authors.affiliation: Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei, Taiwan; Department of Radiation Oncology, Tzu Chi General Hospital Dalin Branch, Chiayi, Taiwan; Association of Medical Radiation Technologists, Taipei, Taiwan.
authors.forename: Wei-Ta
authors.initials: WT
authors.lastname: Tsai
authors.affiliation: Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei, Taiwan; Department of Nuclear Medicine, Taipei Veterans General Hospital, Taipei, Taiwan; Association of Medical Radiation Technologists, Taipei, Taiwan.
authors.forename: Bang-Hung
authors.initials: BH
authors.lastname: Yang
authors.affiliation: Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei, Taiwan; Department of Radiology, Mackay Memorial Hospital, Taipei, Taiwan; Association of Medical Radiation Technologists, Taipei, Taiwan.
authors.forename: Chun-Yuan
authors.initials: CY
authors.lastname: Tu
authors.affiliation: Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei, Taiwan.
authors.forename: Tung-Hsin
authors.initials: TH
authors.lastname: Wu
mesh_terms: D000328:Adult; D003627:Data Interpretation, Statistical; D006257:Head / Q000000981:diagnostic imaging*; D006801:Humans; D061330:Multidetector Computed Tomography / Q000592:standards / Q000706:statistics & numerical data; D011786:Quality Control; D011829:Radiation Dosage; D059629:Signal-To-Noise Ratio; D011795:Surveys and Questionnaires; D013624:Taiwan; D036542:Tomography, Spiral Computed / Q000592:standards / Q000706:statistics & numerical data; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data