title: Estimation and comparison of effective dose (E) in standard chest CT by organ dose measurements and dose-length-product methods and assessment of the influence of CT tube potential (energy dependency) on effective dose in a dual-source CT.
abstract: OBJECTIVE
  To determine effective dose (E) during standard chest CT using an organ dose-based and a dose-length-product-based (DLP) approach for four different scan protocols including high-pitch and dual-energy in a dual-source CT scanner of the second generation.
  
  
  METHODS
  Organ doses were measured with thermo luminescence dosimeters (TLD) in an anthropomorphic male adult phantom. Further, DLP-based dose estimates were performed by using the standard 0.014mSv/mGycm conversion coefficient k. Examinations were performed on a dual-source CT system (Somatom Definition Flash, Siemens). Four scan protocols were investigated: (1) single-source 120kV, (2) single-source 100kV, (3) high-pitch 120kV, and (4) dual-energy with 100/Sn140kV with equivalent CTDIvol and no automated tube current modulation. E was then determined following recommendations of ICRP publication 103 and 60 and specific k values were derived.
  
  
  RESULTS
  DLP-based estimates differed by 4.5-16.56% and 5.2-15.8% relatively to ICRP 60 and 103, respectively. The derived k factors calculated from TLD measurements were 0.0148, 0.015, 0.0166, and 0.0148 for protocol 1, 2, 3 and 4, respectively. Effective dose estimations by ICRP 103 and 60 for single-energy and dual-energy protocols show a difference of less than 0.04mSv.
  
  
  CONCLUSIONS
  Estimates of E based on DLP work equally well for single-energy, high-pitch and dual-energy CT examinations. The tube potential definitely affects effective dose in a substantial way. Effective dose estimations by ICRP 103 and 60 for both single-energy and dual-energy examinations differ not more than 0.04mSv.
authors.affiliation: Department of Diagnostic Radiology, Goethe University-Frankfurt am Main, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany. jijopaul1980@gmail.com
authors.forename: Jijo
authors.initials: J
authors.lastname: Paul
authors.forename: Rosemarie
authors.initials: R
authors.lastname: Banckwitz
authors.forename: Bernhard
authors.initials: B
authors.lastname: Krauss
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Vogl
authors.forename: Werner
authors.initials: W
authors.lastname: Maentele
authors.forename: Ralf W
authors.initials: RW
authors.lastname: Bauer
mesh_terms: D000328:Adult; D001822:Body Burden; D006801:Humans; D008297:Male; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D013902:Radiography, Thoracic / Q000295:instrumentation*; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods; D012062:Relative Biological Effectiveness; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*