title: Pilot study of low-dose nonenhanced computed tomography with iterative reconstruction for diagnosis of urinary stones.
abstract: OBJECTIVE
  To evaluate the efficacy of low-dose computed tomography (LDCT) for detecting urinary stones with the use of an iterative reconstruction technique for reducing radiation dose and image noise.
  
  
  METHODS
  A total of 101 stones from 69 patients who underwent both conventional nonenhanced computed tomography (CCT) and LDCT were analyzed. Interpretations were made of the two scans according to stone characteristics (size, volume, location, Hounsfield unit [HU], and skin-to-stone distance [SSD]) and radiation dose by dose-length product (DLP), effective dose (ED), and image noise. Diagnostic performance for detecting urinary stones was assessed by statistical evaluation.
  
  
  RESULTS
  No statistical differences were found in stone characteristics between the two scans. The average DLP and ED were 384.60 ± 132.15 mGy and 5.77 ± 1.98 mSv in CCT and 90.08 ± 31.80 mGy and 1.34 ± 0.48 mSv in LDCT, respectively. The dose reduction rate of LDCT was nearly 77% for both DLP and ED (p<0.01). The mean objective noise (standard deviation) from three different areas was 23.0 ± 2.5 in CCT and 29.2 ± 3.1 in LDCT with a significant difference (p<0.05); the slight increase was 21.2%. For stones located throughout the kidney and ureter, the sensitivity and specificity of LDCT remained 96.0% and 100%, with positive and negative predictive values of 100% and 96.2%, respectively.
  
  
  CONCLUSIONS
  LDCT showed significant radiation reduction while maintaining high image quality. It is an attractive option in the diagnosis of urinary stones.
authors.affiliation: Department of Urology, Chung-Ang University College of Medicine, Seoul, Korea.
authors.forename: Sang Ho
authors.initials: SH
authors.lastname: Park
authors.affiliation: Department of Urology, Chung-Ang University College of Medicine, Seoul, Korea.
authors.forename: Kyung Do
authors.initials: KD
authors.lastname: Kim
authors.affiliation: Department of Urology, Chung-Ang University College of Medicine, Seoul, Korea.
authors.forename: Young Tae
authors.initials: YT
authors.lastname: Moon
authors.affiliation: Department of Urology, Chung-Ang University College of Medicine, Seoul, Korea.
authors.forename: Soon Chul
authors.initials: SC
authors.lastname: Myung
authors.affiliation: Department of Urology, Chung-Ang University College of Medicine, Seoul, Korea.
authors.forename: Tae Hyoung
authors.initials: TH
authors.lastname: Kim
authors.affiliation: Department of Urology, Chung-Ang University College of Medicine, Seoul, Korea.
authors.forename: In Ho
authors.initials: IH
authors.lastname: Chang
authors.affiliation: Department of Urology, Severance Hospital, Urological Science Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Jong Kyou
authors.initials: JK
authors.lastname: Kwon
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014545:Urinary Calculi / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: Computer-assisted image processing; Radiation; Urinary calculi