title: Radiation exposure and image quality of normal computed tomography brain images acquired with automated and organ-based tube current modulation multiband filtering and iterative reconstruction.
abstract: OBJECTIVE
  We sought to determine whether radiation dose can be reduced and image quality improved in computed tomography (CT) images of the brain that were acquired with automated exposure control (AEC), organ-based tube current modulation (TCM), multiband filtration (MBF), and iterative reconstruction in image space (IRIS).
  
  
  METHODS
  An Alderson-Rando-phantom, equipped with thermoluminescent dosimeters, was used to determine the radiation exposure of organs within the head and neck by different CT brain scan modes. We measured the noise and signal-to-noise ratios and subjectively graded quality criteria in different territories of the brain in spiral CT images of 150 patients. We also derived the radiation exposure from the patient protocols.
  
  
  RESULTS
  In the phantom, AEC and TCM reduced the radiation exposure of the lenses, cerebrum, cerebellum, and thyroid gland by 41.9%, 34.5%, 30.5%, and 34.9%, respectively. Brain CT scans from patients investigated with AEC, TCM, MBF, and IRIS were found to have significantly better image quality than with conventional filtered back projection. In addition, the CT dose index and dose-length product were significantly lower with AEC, TCM, MBF, and IRIS by 24.1% and 20.2%, respectively.
  
  
  CONCLUSIONS
  The combination of AEC, TCM, MBF, and IRIS improves image quality while radiation exposure can be reduced, particularly in dose-sensitive organs, such as the lenses and thyroid gland.
authors.affiliation: Department of Clinical Radiology, Grosshadern Clinic, Ludwig-Maximilians-University, Munich, Germany. christoph.becker@med.uni-muenchen.de
authors.forename: Hans-Christoph
authors.initials: HC
authors.lastname: Becker
authors.forename: Dominik
authors.initials: D
authors.lastname: Augart
authors.forename: Martina
authors.initials: M
authors.lastname: Karpitschka
authors.forename: Stefan
authors.initials: S
authors.lastname: Ulzheimer
authors.forename: Fabian
authors.initials: F
authors.lastname: Bamberg
authors.forename: Dominik
authors.initials: D
authors.lastname: Morhard
authors.forename: Klement
authors.initials: K
authors.lastname: Neumaier
authors.forename: Anno
authors.initials: A
authors.lastname: Graser
authors.forename: Thorsten
authors.initials: T
authors.lastname: Johnson
authors.forename: Maximilian
authors.initials: M
authors.lastname: Reiser
mesh_terms: D000704:Analysis of Variance; D001921:Brain / Q000000981:diagnostic imaging* / Q000473:pathology / Q000528:radiation effects; D006257:Head / Q000000981:diagnostic imaging / Q000473:pathology / Q000528:radiation effects; D006801:Humans; D007908:Lens, Crystalline / Q000000981:diagnostic imaging / Q000473:pathology / Q000528:radiation effects; D009333:Neck / Q000000981:diagnostic imaging / Q000473:pathology / Q000528:radiation effects; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement / Q000295:instrumentation* / Q000379:methods; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods; D059629:Signal-To-Noise Ratio; D013961:Thyroid Gland / Q000000981:diagnostic imaging / Q000473:pathology / Q000528:radiation effects; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000379:methods