title: Feasibility of Dose Optimization in a Second-Generation Dual-Source CT Scanner for a Manufacturer-Recommended Urolithiasis Protocol for Imaging Renal Stones.
abstract: OBJECTIVE
  The purpose of this article is to investigate the magnitude of dose optimization for a manufacturer-recommended urolithiasis protocol in a second-generation dual-source CT scanner.
  
  
  METHODS
  Custom renal phantoms with 24 stones were scanned using the manufacturer-provided dual-energy CT protocol (tube A, 100 kVp and 210 reference mAs; tube B, 140 kVp and 162 reference mAs) and seven dose-optimized protocols in which the reference tube current-time product setting of tube A was reduced stepwise by 20 mAs. Detection and characterization of the stones was assessed. In the patient study, 25 patients underwent the manufacturer-provided dual-energy protocol and 25 patients underwent imaging with a dose-optimized protocol (tube A, 100 kVp and 90 reference mAs; tube B, 140 kVp and 70 reference mAs). Dose-length product (DLP), image noise, and contrast-to-noise ratio (CNR) were assessed. Subjective image quality was analyzed by three independent radiologists.
  
  
  RESULTS
  In the phantom study, the reference tube current-time product of tube A could be reduced from 210 to 90 mAs without losing the accuracy of detection or characterization of the calculi. In the patient study, the dose-optimized protocol resulted in a significant reduction of the average DLP by 51% compared with the standard protocol (219.4 vs 443.5 mGy·cm, respectively; p = 0.0001). The image noise was higher, and the CNR was lower, in the dose-optimized group than in the standard-dose group (p < 0.05). The subjective overall image quality of the dose-optimized CT examinations was rated as good, and that of the standard-dose CT examinations was rated as excellent (p = 0.001).
  
  
  CONCLUSIONS
  The in vitro and in vivo assessment revealed a potential for a 51% dose reduction of the manufacturer-recommended dual-energy CT protocol for urolithiasis without compromising the accuracy.
authors.affiliation: 1 Clinic of Radiology and Nuclear Medicine, University of Basel Hospital, Petersgraben 4, CH-4031 Basel, Switzerland.
authors.forename: Michele
authors.initials: M
authors.lastname: Pansini
authors.affiliation: 2 Institute of Diagnostic and Interventional Radiology, University Hospital Zürich, Zürich, Switzerland.
authors.forename: Fabian
authors.initials: F
authors.lastname: Morsbach
authors.affiliation: 1 Clinic of Radiology and Nuclear Medicine, University of Basel Hospital, Petersgraben 4, CH-4031 Basel, Switzerland.
authors.forename: Tilman
authors.initials: T
authors.lastname: Schubert
authors.affiliation: 1 Clinic of Radiology and Nuclear Medicine, University of Basel Hospital, Petersgraben 4, CH-4031 Basel, Switzerland.
authors.forename: Joachim
authors.initials: J
authors.lastname: Hohmann
authors.affiliation: 1 Clinic of Radiology and Nuclear Medicine, University of Basel Hospital, Petersgraben 4, CH-4031 Basel, Switzerland.
authors.forename: Balazs
authors.initials: B
authors.lastname: Kovács
authors.affiliation: 3 Institute of Radiology, Hospital Centre of Biel, Biel, Switzerland.
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Szucs-Farkas
authors.affiliation: 1 Clinic of Radiology and Nuclear Medicine, University of Basel Hospital, Petersgraben 4, CH-4031 Basel, Switzerland.
authors.forename: Sebastian T
authors.initials: ST
authors.lastname: Schindera
mesh_terms: D000328:Adult; D000368:Aged; D002985:Clinical Protocols; D004307:Dose-Response Relationship, Radiation; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: dose optimization; dual-energy CT; renal stone characterization