title: Size-Specific Dose Estimates for Evaluation of Individual Patient Dose in CT Protocol for Renal Colic.
abstract: OBJECTIVE
  The purpose of this study is to retrospectively evaluate size-specific dose estimates of a renal-colic CT protocol and to assess the quality and diagnostic value of obtained images.
  
  
  METHODS
  The study population included 82 consecutive adult patients with acute renal colic undergoing CT with a reduced radiation dose (noise index, 59.1). The control group included 82 consecutive patients who underwent clinically indicated CT examination of the abdomen and pelvis with a routine-dose CT protocol (noise index, 22.0). The size-specific dose estimate was calculated with volume CT dose index and patient effective diameter. Subjective image quality analysis was based on visibility of the ureter. Ureters were tracked from the renal pelvis to the vesicoureteral junction. Objective image quality was based on the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR).
  
  
  RESULTS
  The size-specific dose estimates in the renal-colic group were 2.7 times lower than those in the control group. A linear relationship between patient size and size-specific dose estimate was noted. In the smallest patient, the conversion factor for the size-specific dose estimate calculation was 1.65. Overall image quality was better for the control patients, but there was no statistically significant difference in ureter visibility. The SNR was higher for the control group, whereas no difference in CNR was found.
  
  
  CONCLUSIONS
  Small patients need the biggest correction for body size and require special attention in radiation dose estimation. We suggest the modification of scanning parameters on the basis of size-specific dose estimate to decrease patient dose in large patients.
authors.affiliation: 1 All authors: Department of General Radiology, Interventional Radiology and Neuroradiology, Wroclaw Medical University, Borowska 213, Wrocław 50-556, Poland.
authors.forename: Łukasz A
authors.initials: ŁA
authors.lastname: Waszczuk
authors.affiliation: 1 All authors: Department of General Radiology, Interventional Radiology and Neuroradiology, Wroclaw Medical University, Borowska 213, Wrocław 50-556, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Guziński
authors.affiliation: 1 All authors: Department of General Radiology, Interventional Radiology and Neuroradiology, Wroclaw Medical University, Borowska 213, Wrocław 50-556, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Czarnecka
authors.affiliation: 1 All authors: Department of General Radiology, Interventional Radiology and Neuroradiology, Wroclaw Medical University, Borowska 213, Wrocław 50-556, Poland.
authors.forename: Marek J
authors.initials: MJ
authors.lastname: Sąsiadek
mesh_terms: D000368:Aged; D003287:Contrast Media; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted; D056844:Renal Colic / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media
keywords: CT; radiation dose; radiation protection; renal colic; size-specific dose estimates