title: Automated computed tomography dose-saving algorithm to protect radiosensitive tissues: estimation of radiation exposure and image quality considerations.
abstract: OBJECTIVE
  To evaluate radiation exposure and image quality in thoracic computed tomography (CT) using a new dose-saving algorithm to protect radiosensitive organs.
  
  
  METHODS
  For dose measurements, an Alderson RANDO phantom equipped with thermoluminescent dosimeters was used. The effective dose was calculated according to the International Commission on Radiologic Protection 103. Exposure was performed on a second-generation dual-source CT. The following parameters for thoracic CT were used: 160 effective mAs, 120 kV, scan range of 30 cm, collimation of 128 × 0.6 mm. For the acquisition, the tube current modulation type XCare was used, which reduces the tube current for anterior tube position to minimize direct exposure to anterior located organs. To compare differences, scans with and without XCare were performed. Objective signal-to-noise measurements were evaluated, and the subjective noise perception was rated in a 3-point scale (1: excellent, 3: affecting diagnostic accuracy) in 30 patients with a standard thoracic examination and a follow-up using XCare.
  
  
  RESULTS
  A substantial dose reduction in radiosensitive tissues was evident using the dose-saving algorithm XCare. Specifically, reductions of 35.2% for the female breast and 20.1% for the thyroid gland were measured, resulting in a decreasing effective whole-body dose of 8.0% and 14.3% for males and females, respectively. The objective and subjective evaluation of image quality showed no significant differences between both scan protocols (P > 0.05). Mean signal-to-noise ratio was 1.3 ± 0.2 and 1.2 ± 0.2 in scan protocols without and with XCare, respectively. The subjective scores at the level of the pulmonary trunk were 1.2 ± 0.4 and 1.4 ± 0.5 in standard chest scan and scans with the dose-saving algorithm XCare, respectively.
  
  
  CONCLUSIONS
  The XCare technique protects radiosensitive organs like the female breast and the thyroid gland without affecting image quality. Therefore, this dose-saving algorithm may be used in thoracic CT examinations in male and female patients.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Tuebingen, Tuebingen, Germany. dominik.ketelsen@med.uni-tuebingen.de
authors.forename: Dominik
authors.initials: D
authors.lastname: Ketelsen
authors.forename: Markus
authors.initials: M
authors.lastname: Buchgeister
authors.forename: Michael
authors.initials: M
authors.lastname: Fenchel
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schmidt
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Flohr
authors.forename: Roland
authors.initials: R
authors.lastname: Syha
authors.forename: Christoph
authors.initials: C
authors.lastname: Thomas
authors.forename: Ilias
authors.initials: I
authors.lastname: Tsiflikas
authors.forename: Claus D
authors.initials: CD
authors.lastname: Claussen
authors.forename: Martin
authors.initials: M
authors.lastname: Heuschmid
mesh_terms: D000465:Algorithms; D001822:Body Burden; D004781:Environmental Exposure / Q000032:analysis / Q000517:prevention & control; D005260:Female; D006801:Humans; D008297:Male; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D011874:Radiometry / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*