title: Individualized assessment of radiation dose in patients undergoing coronary computed tomographic angiography with 256-slice scanning.
abstract: BACKGROUND
  Available data on the radiation burden from coronary computed tomography (CT) angiography (CCTA) are mostly limited to effective dose estimates. This study provides individualized estimates of doses and associated life attributable risks of radiation-induced cancer in a clinical patient population undergoing 256-slice CCTA.
  
  
  RESULTS
  Typical retrospectively and prospectively ECG-gated CCTA exposures in a 256-slice CT scanner were simulated on 52 patient-specific voxelized phantoms. Dose images depicting the dose deposition on the exposed region were generated, and normalized organ doses for all primarily irradiated radiosensitive organs were derived and correlated to patient body habitus. Lung, breast, and esophagus absorbed doses were then determined in 136 consecutive patients subjected to CCTA. Projected life attributable risks of radiation-induced cancer were estimated through the use of appropriate sex-, age- and organ-specific cancer risk factors and compared with corresponding nominal cancer risks. The total projected life attributable risk of radiogenic cancer after CCTA decreases steeply with age at exposure, and lung cancer constitutes the most probable detriment for both sexes. The relative risks of lung cancer associated with prospectively ECG-gated CCTA were 1.0032 and 1.0008 for women and men, respectively. The mean total projected life attributable risks were estimated to be 24.9±7.4 and 71.5±30.0 per 100,000 women undergoing prospectively and retrospectively ECG-gated CCTA, respectively. The corresponding values for men were 7.3±1.3 and 31.4±5.0 per 100 000 patients.
  
  
  CONCLUSIONS
  The mean projected life attributable risks of radiation-induced cancer in a typical clinical patient cohort undergoing standard prospectively ECG-gated CCTA with a 256-slice scanner were found to inconsequentially increase the natural cancer incidence rates.
authors.affiliation: Department of Medical Physics, Faculty of Medicine, University of Crete, Crete, Greece. perisina@med.uoc.gr
authors.forename: Kostas
authors.initials: K
authors.lastname: Perisinakis
authors.forename: Ioannis
authors.initials: I
authors.lastname: Seimenis
authors.forename: Antonis
authors.initials: A
authors.lastname: Tzedakis
authors.forename: Antonios E
authors.initials: AE
authors.lastname: Papadakis
authors.forename: John
authors.initials: J
authors.lastname: Damilakis
mesh_terms: D000368:Aged; D015331:Cohort Studies; D017023:Coronary Angiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology* / Q000209:etiology; D011446:Prospective Studies; D011829:Radiation Dosage; D012189:Retrospective Studies; D012307:Risk Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*