title: Effects of lesion positioning on digital magnification mammography performance.
abstract: OBJECTIVE
  We undertook this study to determine whether differences in detector-lesion distance resulted in appreciable effects on digital magnification mammography performance as measured using the American College of Radiology (ACR) mammography phantom and a line pair test pattern.
  
  
  METHODS
  Images of the standard 42-mm thick standard ACR mammography phantom with a wax insert on one side containing simulated fibers, calcifications, and masses were obtained on a Senographe Essential digital mammography system with the phantom in upright and inverted positions. The process was repeated with a line pair test pattern for measuring resolution. All images were obtained in contact mode, and with 1.5x and 1.8x magnification, and evaluated on a GE PACS monitor.
  
  
  RESULTS
  Overall, changing lesion-detector distance using standard versus inverted positioning did not appreciably increase the number of objects seen on the ACR phantom under all modes. No greater than one line pair difference was seen in standard versus inverted positioning. At 1.8x magnification mode, no difference was detected in line pair resolution with a change in positioning.
  
  
  CONCLUSIONS
  Differences in lesion-detector distance as modeled using both the ACR mammography phantom and a line pair test pattern did not make an appreciable difference in digital magnification mammography performance.
authors.affiliation: Seattle Cancer Care Alliance, Department of Radiology, 825 Eastlake Avenue, Seattle, WA 98109, USA. fl@u.washington.edu
authors.forename: Franklin
authors.initials: F
authors.lastname: Liu
authors.forename: Kalpana M
authors.initials: KM
authors.lastname: Kanal
authors.forename: Brent K
authors.initials: BK
authors.lastname: Stewart
authors.forename: Constance D
authors.initials: CD
authors.lastname: Lehman
mesh_terms: D000465:Algorithms; D016477:Artifacts; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement / Q000295:instrumentation / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity