title: Half-dose non-contrast CT in the investigation of urolithiasis: image quality improvement with third-generation integrated circuit CT detectors.
abstract: OBJECTIVE
  The objective of this study is to establish the effect of third-generation integrated circuit (IC) CT detector on objective image quality in full- and half-dose non-contrast CT of the urinary tract.
  
  
  METHODS
  51 consecutive patients with acute renal colic underwent non-contrast CT of the urinary tract using a 128-slice dual-source CT before (n = 24) and after (n = 27) the installation of third-generation IC detectors. Half-dose images were generated using projections from detector A using the dual-source RAW data. Objective image noise in the liver, spleen, right renal cortex, and right psoas muscle was compared between DC and IC cohorts for full-dose and half-dose images reconstructed with FBP and IR algorithms using 1 cm(2) regions of interest. Presence and size of obstructing ureteric calculi were also compared for full-dose and half-dose reconstructions using DC and IC detectors.
  
  
  RESULTS
  No statistical difference in age and lateral body size was found between patients in the IC and DC cohorts. Radiation dose, as measured by size-specific dose estimates, did not differ significantly either between the two cohorts (10.02 ± 4.54 mGy IC vs. 12.28 ± 7.03 mGy DC). At full dose, objective image noise was not significantly lower in the IC cohort as compared to the DC cohort for the liver, spleen, and right psoas muscle. At half dose, objective image noise was lower in the IC cohort as compared to DC cohort at the liver (21.32 IC vs. 24.99 DC, 14.7% decrease, p < 0.001), spleen (19.33 IC vs. 20.83 DC, 7.20% decrease, p = 0.02), and right renal cortex (20.28 IC vs. 22.98 DC, 11.7% decrease, p = 0.005). Mean obstructing ureteric calculi size was not significantly different when comparison was made between full-dose and half-dose images, regardless of detector type (p > 0.05 for all comparisons).
  
  
  CONCLUSIONS
  Third-generation IC detectors result in lower objective image noise at full- and half-radiation dose levels as compared with traditional DC detectors. The magnitude of noise reduction was greater at half-radiation dose indicating that the benefits of using novel IC detectors are greater in low and ultra-low-dose CT imaging.
authors.affiliation: Faculty of Medicine, University of British Columbia, Vancouver, V5Z 1M9, Canada, junwang.ubc@gmail.com.
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Tony
authors.initials: T
authors.lastname: Kang
authors.forename: Chesnal
authors.initials: C
authors.lastname: Arepalli
authors.forename: Sarah
authors.initials: S
authors.lastname: Barrett
authors.forename: Tim
authors.initials: T
authors.lastname: O'Connell
authors.forename: Luck
authors.initials: L
authors.lastname: Louis
authors.forename: Savvakis
authors.initials: S
authors.lastname: Nicolaou
authors.forename: Patrick
authors.initials: P
authors.lastname: McLaughlin
mesh_terms: D000328:Adult; D000368:Aged; D003287:Contrast Media; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D056844:Renal Colic / Q000000981:diagnostic imaging* / Q000209:etiology; D014057:Tomography, X-Ray Computed; D052878:Urolithiasis / Q000150:complications / Q000000981:diagnostic imaging*
chemical_list: D003287:Contrast Media