title: Lateral topography for reducing effective dose in low-dose chest CT.
abstract: OBJECTIVE
  The purposes of this study were to assess radiation exposure during low-dose chest CT by using lateral topography and to compare the lateral topographic findings with findings obtained with anteroposterior topography alone and anteroposterior and lateral topography combined.
  
  
  METHODS
  From November 2011 to February 2012, 210 male subjects were enrolled in the study. Age, weight, and height of the men were recorded. All subjects were placed into one of three subgroups based on the type of topographic image obtained: anteroposterior topography, lateral topography, and both anteroposterior and lateral topography. Imaging was performed with a 128-MDCT scanner. CT, except for topography, was the same for all subjects. A radiologist analyzed each image, recorded scan length, checked for any insufficiencies in the FOV, and calculated the effective radiation dose. One-way analysis of variance and multiple comparisons were used to compare the effective radiation exposure and scan length between groups.
  
  
  RESULTS
  The mean scan length in the anteroposterior topography group was significantly greater than that of the lateral topography group and the combined anteroposterior and lateral topography group (p < 0.001). The mean effective radiation dose for the lateral topography group (0.735 ± 0.033 mSv) was significantly lower than that for the anteroposterior topography group (0.763 ± 0.038 mSv) and the combined anteroposterior and lateral topography group (0.773 ± 0.038) (p < 0.001).
  
  
  CONCLUSIONS
  Lateral topographic low-dose CT was associated with a lower effective radiation dose and scan length than either anteroposterior topographic low-dose chest CT or low-dose chest CT with both anteroposterior and lateral topograms.
authors.affiliation: Department of Radiology, Aerospace Medical Center, PO Box 335-21, Ssangsu-ri, Namil-myeon, Cheongwongun, Chungbuk, Korea. cafri1213@hanmail.net
authors.forename: Dong-Ho
authors.initials: DH
authors.lastname: Bang
authors.forename: Daekeon
authors.initials: D
authors.lastname: Lim
authors.forename: Wi-Sub
authors.initials: WS
authors.lastname: Hwang
authors.forename: Seong-Hoon
authors.initials: SH
authors.lastname: Park
authors.forename: Ok-man
authors.initials: OM
authors.lastname: Jeong
authors.forename: Kyung Wook
authors.initials: KW
authors.lastname: Kang
authors.forename: Hohyung
authors.initials: H
authors.lastname: Kang
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D056888:Patient Positioning; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D013902:Radiography, Thoracic; D014057:Tomography, X-Ray Computed