title: Combining automated attenuation-based tube voltage selection and iterative reconstruction: a liver phantom study.
abstract: OBJECTIVE
  To determine the value of combined automated attenuation-based tube-potential selection and iterative reconstructions (IRs) for optimising computed tomography (CT) imaging of hypodense liver lesions.
  
  
  METHODS
  A liver phantom containing hypodense lesions was imaged by CT with and without automated attenuation-based tube-potential selection (80, 100 and 120 kVp). Acquisitions were reconstructed with filtered back projection (FBP) and sinogram-affirmed IR. Image noise and contrast-to-noise ratio (CNR) were measured. Two readers marked lesion localisation and rated confidence, sharpness, noise and image quality on a five-point scale (1 = worst, 5 = best).
  
  
  RESULTS
  Image noise was lower (31-52%) and CNR higher (43-102%) on IR than on FBP images at all tube voltages. On 100-kVp and 80-kVp IR images, confidence and sharpness were higher than on 120-kVp FBP images. Scores for image quality score and noise as well as sensitivity for 100-kVp IR were similar or higher than for 120-kVp FBP and lower for 80-kVp IR. Radiation dose was reduced by 26% at 100 kVp and 56% at 80 kVp.
  
  
  CONCLUSIONS
  Compared with 120-kVp FBP images, the combination of automated attenuation-based tube-potential selection at 100 kVp and IR provides higher image quality and improved sensitivity for detecting hypodense liver lesions in vitro at a dose reduced by 26%.
  
  
  CONCLUSIONS
  • Combining automated tube voltage selection/iterative CT reconstruction improves image quality. • Attenuation values remain stable on IR compared with FBP images. • Lesion detection was highest on 100-kVp IR images.
authors.affiliation: Institute for Diagnostic and Interventional Radiology, University Hospital Zurich, Raemistrasse 100, 8091, Zurich, Switzerland, danielahusarik@yahoo.com.
authors.forename: Daniela B
authors.initials: DB
authors.lastname: Husarik
authors.forename: Sebastian T
authors.initials: ST
authors.lastname: Schindera
authors.forename: Fabian
authors.initials: F
authors.lastname: Morsbach
authors.forename: Natalie
authors.initials: N
authors.lastname: Chuck
authors.forename: Burkhardt
authors.initials: B
authors.lastname: Seifert
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Szucs-Farkas
authors.forename: Hatem
authors.initials: H
authors.lastname: Alkadhi
mesh_terms: D000465:Algorithms; D016477:Artifacts; D008099:Liver / Q000000981:diagnostic imaging*; D008107:Liver Diseases / Q000000981:diagnostic imaging*; D008111:Liver Function Tests; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods* / Q000592:standards