title: Estimation of radiation exposure of prospectively triggered 128-slice computed tomography coronary angiography.
abstract: OBJECTIVE
  To estimate the effective dose of prospectively triggered computed tomography coronary angiography (CTCA) in step-and-shoot (SAS) mode, depending on the tube current and tube voltage modulation.
  
  
  METHODS
  For dose measurements, an Alderson-Rando-phantom equipped with thermoluminescent dosimeters was used. The effective dose was calculated according to ICRP 103. Exposure was performed on a 128-slice single source scanner providing a collimation of 128 × 0.6 mm and a rotation time of 0.38 seconds. CTCA in the SAS mode was acquired with variation of the tube current (160, 240, 320 mAs) and tube voltage (100, 120, 140 kV) at a simulated heart rate of 60 beats per minute and a scan range of 13.5 cm.
  
  
  RESULTS
  Depending on gender, tube current and tube voltage, the effective dose of a CTCA in SAS mode varies from 2.8 to 10.8 mSv. Due to breast tissue in the primary scan range, exposure in the case of females showed an increase of up to 60.0 ± .4% compared to males. The dose reduction achieved by a reduction of tube current showed a significant positive, linear correlation to effective dose with a possible decrease in the effective dose of up to 60.4% (r = 0.998; p = 0.044). Disproportionately high, the estimated effective dose can be reduced by using a lower tube voltage with a dose reduction of up to 52.4%.
  
  
  CONCLUSIONS
  Further substantial dose reduction of low-dose CTCA in SAS mode can be achieved by adapting the tube current and tube voltage and should be implemented in the clinical routine, i. e. adapting those protocol parameters to patient body weight.
authors.affiliation: Abteilung für Diagnostische und Interventionelle Radiologie, Eberhard-Karls-Universität Tübingen. dominik.ketelsen@med.unitübingen.de
authors.forename: D
authors.initials: D
authors.lastname: Ketelsen
authors.forename: M
authors.initials: M
authors.lastname: Buchgeister
authors.forename: M
authors.initials: M
authors.lastname: Fenchel
authors.forename: C
authors.initials: C
authors.lastname: Thomas
authors.forename: N
authors.initials: N
authors.lastname: Boehringer
authors.forename: I
authors.initials: I
authors.lastname: Tsiflikas
authors.forename: M
authors.initials: M
authors.lastname: Kaempf
authors.forename: R
authors.initials: R
authors.lastname: Syha
authors.forename: C D
authors.initials: CD
authors.lastname: Claussen
authors.forename: M
authors.initials: M
authors.lastname: Heuschmid
mesh_terms: D001822:Body Burden; D001940:Breast / Q000528:radiation effects; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D017023:Coronary Angiography / Q000009:adverse effects*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008168:Lung / Q000528:radiation effects; D008297:Male; D019047:Phantoms, Imaging; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013737:Testis / Q000528:radiation effects; D013819:Thermoluminescent Dosimetry; D013961:Thyroid Gland / Q000528:radiation effects; D014057:Tomography, X-Ray Computed / Q000009:adverse effects*