title: Dose Assessment in Computed Tomography Examination and Establishment of Local Diagnostic Reference Levels in Mazandaran, Iran.
abstract: BACKGROUND
  Medical X-rays are the largest man-made source of public exposure to ionizing radiation. While the benefits of Computed Tomography (CT) are well known in accurate diagnosis, those benefits are not risk-free. CT is a device with higher patient dose in comparison with other conventional radiation procedures.
  
  
  OBJECTIVE
  This study is aimed at evaluating radiation dose to patients from Computed Tomography (CT) examination in Mazandaran hospitals and defining diagnostic reference level (DRL).
  
  
  METHODS
  Patient-related data on CT protocol for four common CT examinations including brain, sinus, chest and abdomen & pelvic were collected. In each center, Computed Tomography Dose Index (CTDI) measurements were performed using pencil ionization chamber and CT dosimetry phantom according to AAPM report No. 96 for those techniques. Then, Weighted Computed Tomography Dose Index (CTDIW), Volume Computed Tomography Dose Index (CTDI vol) and Dose Length Product (DLP) were calculated.
  
  
  RESULTS
  The CTDIw for brain, sinus, chest and abdomen & pelvic ranged (15.6-73), (3.8-25. 8), (4.5-16.3) and (7-16.3), respectively. Values of DLP had a range of (197.4-981), (41.8-184), (131-342.3) and (283.6-486) for brain, sinus, chest and abdomen & pelvic, respectively. The 3rd quartile of CTDIW, derived from dose distribution for each examination is the proposed quantity for DRL. The DRLs of brain, sinus, chest and abdomen & pelvic are measured 59.5, 17, 7.8 and 11 mGy, respectively.
  
  
  CONCLUSIONS
  Results of this study demonstrated large scales of dose for the same examination among different centers. For all examinations, our values were lower than international reference doses.
authors.affiliation: School of Medicine, Babol University of Medical Sciences, Babol, Iran.
authors.forename: A
authors.initials: A
authors.lastname: Janbabanezhad Toori
authors.affiliation: Department of Medical Physics, Faculty of Medicine, Babol University of Medical Sciences, Babol, Iran.
authors.forename: A
authors.initials: A
authors.lastname: Shabestani-Monfared
authors.affiliation: Department of Medical Physics, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: M R
authors.initials: MR
authors.lastname: Deevband
authors.affiliation: Department of Radiology, Mazandaran University of Medical Sciences, Sari, Iran.
authors.forename: R
authors.initials: R
authors.lastname: Abdi
authors.affiliation: Department of Radiology, Babol University of Medical Sciences, Babol, Iran.
authors.forename: M
authors.initials: M
authors.lastname: Nabahati
keywords: CTDI; Computed Tomography; DLP; Diagnostic Reference Levels; Mazandaran