title: Variations in breast doses for an automatic mammography unit.
abstract: OBJECTIVE
  To assess variations of glandular doses for a group of patients when different dose modes are selected for a specific system.
  
  
  METHODS
  All measurements were obtained with a Senographe DMR mammography unit (GE Medical Systems). Automatic exposure control with either contrast or standard mode was routinely used in patient examinations. Entrance surface air kerma (ESAK) values were estimated from the postexposure mAs and from the recorded data. Subsequently the mean glandular dose (MGD) for each view was calculated using the conversion factors assuming 50% glandular and 50% adipose tissue composition.
  
  
  RESULTS
  The average MGD for the right craniocaudal view for all beam qualities was 1.65 mGy, and 46.7 mm was the average compressed breast thickness for this view. Average MGDs were 1.61, 1.76, and 1.35 mGy for Mo-Mo, Mo-Rh, and Rh-Rh anode filter selections, respectively. Conversely, 2.18 and 1.47 of breast doses were measured for contrast and standard dose modes at the most often used (Mo-Mo) anode filter selection.
  
  
  CONCLUSIONS
  Breast dose measurement techniques with the standard phantom or on real patients are easy to implement for the mammography users. Obtaining ESAK versus breast thickness relationship is useful for retrospective dose evaluation; better correlation can be established (67% vs. 52%) if they are generated separately for each dose modes.
authors.affiliation: Department of Engineering Physics, Faculty of Engineering, Ankara University, Ankara, Turkey. bor@eng.ankara.edu.tr
authors.forename: Doğan
authors.initials: D
authors.lastname: Bor
authors.forename: Selma
authors.initials: S
authors.lastname: Tükel
authors.forename: Turan
authors.initials: T
authors.lastname: Olgar
authors.forename: Elif
authors.initials: E
authors.lastname: Aydin
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D001823:Body Composition; D001940:Breast / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D008327:Mammography / Q000379:methods*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000517:prevention & control*; D011856:Radiographic Image Enhancement / Q000379:methods*; D011874:Radiometry / Q000379:methods*; D018570:Risk Assessment; D012307:Risk Factors