title: Raw data-based iterative reconstruction in body CTA: evaluation of radiation dose saving potential.
abstract: OBJECTIVE
  To evaluate prospectively, in patients undergoing body CTA, the radiation dose saving potential of raw data-based iterative reconstruction as compared to filtered back projection (FBP).
  
  
  METHODS
  Twenty-five patients underwent thoraco-abdominal CTA with 128-slice dual-source CT, operating both tubes at 120 kV. Full-dose (FD) images were reconstructed with FBP and were compared to half-dose (HD) images with FBP and HD-images with sinogram-affirmed iterative reconstruction (SAFIRE), both reconstructed using data from only one tube-detector-system. Image quality and sharpness of the aortic contour were assessed. Vessel attenuation and noise were measured, contrast-to-noise-ratio was calculated.
  
  
  RESULTS
  Noise as image quality deteriorating artefact occurred in 24/25 (96%) HD-FBP but not in FD-FBP and HD-raw data-based iterative reconstruction datasets (p < 0.001). Other artefacts occurred with similar prevalence among the datasets. Sharpness of the aortic contour was higher for FD-FBP and HD-raw data-based iterative reconstruction as compared to HD-FBP (p < 0.001). Aortoiliac attenuation was similar among all datasets (p > 0.05). Lowest noise was found for HD-raw data-based iterative reconstruction (7.23HU), being 9.4% lower than that in FD-FBP (7.98HU, p < 0.05) and 30.8% lower than in HD-FBP images (10.44HU, p < 0.001). Contrast-to-noise-ratio was lower in HD-FBP (p < 0.001) and higher in HD-raw data-based iterative reconstruction (p < 0.001) as compared to FD-FBP.
  
  
  CONCLUSIONS
  Intra-individual comparisons of image quality of body CTA suggest that raw data-based iterative reconstruction allows for dose reduction >50% while maintaining image quality. Key Points • Raw data-based iterative reconstruction reduces image noise and improves image quality as compared to filtered back projection • At a similar radiation dose, raw data-based iterative reconstruction improves the sharpness of vessel contours • In body CTA a dose reduction of >50% might be possible when using raw data-based iterative reconstructions, while image quality can be maintained.
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Raemistrasse 100, Ch-8091 Zurich, Switzerland.
authors.forename: Anna
authors.initials: A
authors.lastname: Winklehner
authors.forename: Christoph
authors.initials: C
authors.lastname: Karlo
authors.forename: Gilbert
authors.initials: G
authors.lastname: Puippe
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schmidt
authors.forename: Thomas
authors.initials: T
authors.lastname: Flohr
authors.forename: Robert
authors.initials: R
authors.lastname: Goetti
authors.forename: Thomas
authors.initials: T
authors.lastname: Pfammatter
authors.forename: Thomas
authors.initials: T
authors.lastname: Frauenfelder
authors.forename: Hatem
authors.initials: H
authors.lastname: Alkadhi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000704:Analysis of Variance; D001011:Aorta / Q000473:pathology* / Q000528:radiation effects; D003251:Constriction, Pathologic / Q000000981:diagnostic imaging; D003287:Contrast Media; D017023:Coronary Angiography / Q000379:methods*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D007083:Iliac Artery / Q000000981:diagnostic imaging / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D003287:Contrast Media