title: Assessment of radiation dose from abdominal quantitative CT with short scan length.
abstract: OBJECTIVE
  To assess radiation dose for patients who received abdominal quantitative CT and to compare the midpoint dose [DL(0)] at the centre of a 1-cm scan length with the volume CT dose index (CTDIvol). Although the size-specific dose estimate (SSDE) proposed in The American Association of Physicists in Medicine Report No. 204 is not applicable for short-length scans, commercial dose-monitoring software, such as Radimetrics™Enterprise Platform (Bayer HealthCare, Whippany, NJ), reports SSDE for all scans. SSDE was herein compared with DL(0).
  
  
  METHODS
  Data were analyzed from 398 abdominal quantitative CT examinations in 165 males and 233 females. The CTDIvolwas 4.66 mGy, and the scan length was 1 cm for all examinations. Radimetrics was used to extract patient diameter and SSDE. DL(0) was assessed using a previously reported method that takes into account both patient size and scan length.
  
  
  RESULTS
  The mean patient diameter was 28.5 ± 6.3 cm (range, 16.5-46.6 cm); the mean SSDE was 6.22 ± 1.36 mGy (range, 3.12-9.42 mGy); and the mean DL(0) was 2.97 ± 0.95 mGy (range, 1.18-5.77 mGy). As patient diameter increased, the DL(0) to CTDIvolratio decreased, ranging from 1.24 to 0.25; the DL(0) to SSDE ratio also decreased, ranging from 0.61 to 0.38.
  
  
  CONCLUSIONS
  The dose to the patients from abdominal quantitative CT may be largely different from CTDIvoland SSDE. This study demonstrates the necessity of taking into account not only patient size but also scan length for evaluating the dose from short-length scans. Advances in knowledge: In CT examinations with 1-cm scan length, dose evaluation needs to take into account both patient size and scan length. An omission of either factor can result in an erroneous result.
authors.affiliation: Division of Diagnostic Imaging Physics, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Xinhua
authors.initials: X
authors.lastname: Li
authors.affiliation: Division of Diagnostic Imaging Physics, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Kai
authors.initials: K
authors.lastname: Yang
authors.affiliation: Division of Diagnostic Imaging Physics, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: DeLorenzo
authors.affiliation: Division of Diagnostic Imaging Physics, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Bob
authors.initials: B
authors.lastname: Liu
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011860:Radiography, Abdominal / Q000379:methods*; D011874:Radiometry; D012984:Software; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*