title: Radiation dose reduction in parasinus CT by spectral shaping.
abstract: BACKGROUND
  Spectral shaping aims to narrow the X-ray spectrum of clinical CT. The aim of this study was to determine the image quality and the extent of radiation dose reduction that can be achieved by tin prefiltration for parasinus CT.
  
  
  METHODS
  All scans were performed with a third generation dual-source CT scanner. A study protocol was designed using 100 kV tube voltage with tin prefiltration (200 mAs) that provides image noise levels comparable to a low-dose reference protocol using 100 kV without spectral shaping (25 mAs). One hundred consecutive patients were prospectively enrolled and randomly assigned to the study or control group. All patients signed written informed consent. The study protocol was approved by the local Institutional Review Board and applies to the HIPAA. Subjective and objective image quality (attenuation values, image noise, and contrast-to-noise ratio (CNR)) were assessed. Radiation exposure was assessed as volumetric CT dose index, and effective dose was estimated. Mann-Whitney U test was performed for radiation exposure and for image noise comparison.
  
  
  RESULTS
  All scans were of diagnostic image quality. Image noise in air, in the retrobulbar fat, and in the eye globe was comparable between both groups (all p > 0.05). CNReye globe/airdid not differ significantly between both groups (p = 0.7). Radiation exposure (1.7 vs. 2.1 mGy, p < 0.01) and effective dose (0.055 vs. 0.066 mSv, p < 0.01) were significantly reduced in the study group.
  
  
  CONCLUSIONS
  Radiation dose can be further reduced by 17% for low-dose parasinus CT by tin prefiltration maintaining diagnostic image quality.
authors.affiliation: Department of Radiology, University Hospital Erlangen, Maximiliansplatz 1, 91054, Erlangen, Germany.
authors.forename: Matthias S
authors.initials: MS
authors.lastname: May
authors.affiliation: Department of Radiology, University Hospital Erlangen, Maximiliansplatz 1, 91054, Erlangen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Brand
authors.affiliation: Department of Radiology, University Hospital Erlangen, Maximiliansplatz 1, 91054, Erlangen, Germany.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Lell
authors.affiliation: Siemens Healthcare GmbH, Forchheim, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Sedlmair
authors.affiliation: Siemens Healthcare GmbH, Forchheim, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Allmendinger
authors.affiliation: Department of Radiology, University Hospital Erlangen, Maximiliansplatz 1, 91054, Erlangen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Uder
authors.affiliation: Department of Radiology, University Hospital Erlangen, Maximiliansplatz 1, 91054, Erlangen, Germany. wolfgang.wuest@uk-erlangen.de.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wuest
mesh_terms: D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009010:Monte Carlo Method; D010254:Paranasal Sinus Diseases / Q000000981:diagnostic imaging*; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D014001:Tin; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D014001:Tin
keywords: Parasinus CT; Spectral shaping; Tin filtration