title: Establishment of institutional diagnostic reference level for computed tomography with automated dose-tracking software.
abstract: BACKGROUND
  The aim of this study was to establish institutional diagnostic reference levels (DRLs) by summarising doses collected across the five computed tomography (CT) system in our institution.
  
  
  METHODS
  CT dose data of 15940 patients were collected retrospectively from May 2015 to October 2015 in five institutional scanners. The mean, 75th percentile and 90th percentile of the dose spread were calculated according to anatomic region. The common CT examinations such as head, chest, combined abdomen/pelvis (A/P), and combined chest/abdomen/pelvis (C/A/P) were reviewed. Distribution of CT dose index (CTDIvol), dose-length product (DLP) and effective dose (ED) were extracted from the data for single-phasic and multiphasic examinations.
  
  
  RESULTS
  The institutional DRL for our CT units were established as mean (50th percentile) of CTDIvol (mGy), DLP (mGy.cm) and ED (mSv) for single and multiphasic studies using the dose-tracking software. In single phasic examination, Head: (49.0 mGy), (978.0 mGy.cm), (2.4 mSv) respectively; Chest: (6.0 mGy), (254.0 mGy.cm), (4.9 mSv) respectively; CT A/P (10.0 mGy), (514.0 mGy.cm), (8.9 mSv) respectively; CT C/A/P (10.0 mGy), (674.0 mGy.cm), (11.8 mSv) respectively. In multiphasic studies: Head (45.0 mGy), (1822.0 mGy.cm), (5.0 mSv) respectively; Chest (8.0 mGy), (577.0 mGy.cm), (10.0 mSv) respectively; CT A/P: (10.0 mGy), (1153.0 mGy.cm), (20.2 mSv) respectively; CT C/A/P: (11.0 mGy), (1090.0 mGy.cm), (19.2 mSv) respectively.
  
  
  CONCLUSIONS
  The reported metrics offer a variety of information that institutions can use for quality improvement activities. The variations in dose between scanners suggest a large potential for optimisation of radiation dose.
authors.affiliation: Department of Diagnostic Imaging, National University Hospital, Singapore.
authors.forename: Chong R
authors.initials: CR
authors.lastname: Liang
authors.affiliation: Department of Diagnostic Imaging, National University Hospital, Singapore.
authors.forename: Priscilla X H
authors.initials: PXH
authors.lastname: Chen
authors.affiliation: Department of Diagnostic Imaging, National University Hospital, Singapore.
authors.forename: Jeevesh
authors.initials: J
authors.lastname: Kapur
authors.affiliation: Department of Diagnostic Imaging, National University Hospital, Singapore.
authors.forename: Michael K L
authors.initials: MKL
authors.lastname: Ong
authors.affiliation: Department of Diagnostic Imaging, National University Hospital, Singapore.
authors.forename: Swee T
authors.initials: ST
authors.lastname: Quek
authors.affiliation: Department of Diagnostic Imaging, National University Hospital, Singapore.
authors.forename: Subhash C
authors.initials: SC
authors.lastname: Kapur
mesh_terms: D000328:Adult; D001331:Automation; D006801:Humans; D011829:Radiation Dosage; D012016:Reference Values; D012189:Retrospective Studies; D012984:Software; D014057:Tomography, X-Ray Computed / Q000592:standards*
keywords: CT dose index; diagnostic reference level; dose-length product; effective dose