title: Evaluation of dose reduction and image quality in CT colonography: comparison of low-dose CT with iterative reconstruction and routine-dose CT with filtered back projection.
abstract: OBJECTIVE
  To prospectively evaluate the radiation dose and image quality comparing low-dose CT colonography (CTC) reconstructed using different levels of iterative reconstruction techniques with routine-dose CTC reconstructed with filtered back projection.
  
  
  METHODS
  Following institutional ethics clearance and informed consent procedures, 210 patients underwent screening CTC using automatic tube current modulation for dual positions. Examinations were performed in the supine position with a routine-dose protocol and in the prone position, randomly applying four different low-dose protocols. Supine images were reconstructed with filtered back projection and prone images with iterative reconstruction. Two blinded observers assessed the image quality of endoluminal images. Image noise was quantitatively assessed by region-of-interest measurements.
  
  
  RESULTS
  The mean effective dose in the supine series was 1.88 mSv using routine-dose CTC, compared to 0.92, 0.69, 0.57, and 0.46 mSv at four different low doses in the prone series (p < 0.01). Overall image quality and noise of low-dose CTC with iterative reconstruction were significantly improved compared to routine-dose CTC using filtered back projection. The lowest dose group had image quality comparable to routine-dose images.
  
  
  CONCLUSIONS
  Low-dose CTC with iterative reconstruction reduces the radiation dose by 48.5 to 75.1% without image quality degradation compared to routine-dose CTC with filtered back projection.
  
  
  CONCLUSIONS
  • Low-dose CTC reduces radiation dose ≥ 48.5% compared to routine-dose CTC. • Iterative reconstruction improves overall CTC image quality compared with FBP. • Iterative reconstruction reduces overall CTC image noise compared with FBP. • Automated exposure control with iterative reconstruction is useful for low-dose CTC.
authors.affiliation: Department of Radiology, Kameda Medical Center, 929 Higashi-cho, Kamogawa, Chiba, 296-8602, Japan, Nagata7@aol.com.
authors.forename: Koichi
authors.initials: K
authors.lastname: Nagata
authors.forename: Masanori
authors.initials: M
authors.lastname: Fujiwara
authors.forename: Hidenori
authors.initials: H
authors.lastname: Kanazawa
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Mogi
authors.forename: Nao
authors.initials: N
authors.lastname: Iida
authors.forename: Toru
authors.initials: T
authors.lastname: Mitsushima
authors.forename: Alan T
authors.initials: AT
authors.lastname: Lefor
authors.forename: Hideharu
authors.initials: H
authors.lastname: Sugimoto
mesh_terms: D002985:Clinical Protocols; D003108:Colonic Diseases; D023881:Colonography, Computed Tomographic / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods*; D011446:Prospective Studies; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*
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