title: Individualization of abdominopelvic CT protocols with lower tube voltage to reduce i.v. contrast dose or radiation dose.
abstract: OBJECTIVE
  The purpose of this study was to validate an individualized approach to contrast-enhanced body CT using size-specific tube potential selection to reduce either i.v. contrast or radiation dose while maintaining diagnostic image quality.
  
  
  METHODS
  With a validated noise insertion method and retrospective image quality assessment (scale 1-5, ≥ 3 acceptable), the lowest acceptable iodine contrast-to-noise ratio (CNR) was determined for 25 body CT examinations. Age-appropriate CT protocols with size-specific tube potential selection were then developed to accomplish two goals: i.v. contrast dose reduction for patients 50 years old and older and radiation dose reduction for patients younger than 50 years. After implementation, subjective and objective image quality metrics were retrospectively compared between the individualized scans and previous fixed-tube-potential scans.
  
  
  RESULTS
  Diagnostically acceptable iodine CNR was achieved with use of up to 40% dose reduction from the baseline protocol. At this dose level, results of logistic regression analysis predicted 94% probability of acceptable image quality. With the individualized protocols that targeted this iodine CNR, 84 patients 50 years old and older had a mean i.v. contrast dose reduction of 26% (100.9 ± 20.7 mL vs 136.2 ± 24.9 mL; p < 0.001) with unchanged image quality scores (4.6 ± 0.5 vs 4.6 ± 0.4; p = 0.160). Thirty patients younger than 50 years had a mean radiation dose reduction of 41% (mean volume CT dose index, 11.6 ± 5.3 mGy vs 19.7 ± 7.8 mGy; p < 0.001) with acceptable but slightly reduced mean image quality scores (4.1 ± 0.4 vs 4.7 ± 0.4; p < 0.001).
  
  
  CONCLUSIONS
  With the use of age-appropriate scan protocols and size-specific selection of tube potential, acceptable image quality can be maintained while i.v. contrast dose or radiation dose is substantially lowered.
authors.affiliation: Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA. hough.david@mayo.edu
authors.forename: David M
authors.initials: DM
authors.lastname: Hough
authors.forename: Lifeng
authors.initials: L
authors.lastname: Yu
authors.forename: Maria M
authors.initials: MM
authors.lastname: Shiung
authors.forename: Rickey E
authors.initials: RE
authors.lastname: Carter
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Geske
authors.forename: Shuai
authors.initials: S
authors.lastname: Leng
authors.forename: Jeff L
authors.initials: JL
authors.lastname: Fidler
authors.forename: James E
authors.initials: JE
authors.lastname: Huprich
authors.forename: D Y
authors.initials: DY
authors.lastname: Jondal
authors.forename: Cynthia H
authors.initials: CH
authors.lastname: McCollough
authors.forename: Joel G
authors.initials: JG
authors.lastname: Fletcher
mesh_terms: D000328:Adult; D000368:Aged; D002985:Clinical Protocols; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008223:Lymphoma / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D051598:Whole Body Imaging
chemical_list: D003287:Contrast Media