title: Analysis of motion during the breast clamping phase of mammography.
abstract: OBJECTIVE
  To measure paddle motion during the clamping phase of a breast phantom for a range of machine/paddle combinations.
  
  
  METHODS
  A deformable breast phantom was used to simulate a female breast. 12 mammography machines from three manufacturers with 22 flexible and 20 fixed paddles were evaluated. Vertical motion at the paddle was measured using two calibrated linear potentiometers. For each paddle, the motion in millimetres was recorded every 0.5 s for 40 s, while the phantom was compressed with 80 N. Independent t-tests were used to determine differences in paddle motion between flexible and fixed, small and large, GE Senographe Essential (General Electric Medical Systems, Milwaukee, WI) and Hologic Selenia Dimensions paddles (Hologic, Bedford, MA). Paddle tilt in the medial-lateral plane for each machine/paddle combination was calculated.
  
  
  RESULTS
  All machine/paddle combinations demonstrate highest levels of motion during the first 10 s of the clamping phase. The least motion is 0.17 ± 0.05 mm/10 s (n = 20) and the most motion is 0.51 ± 0.15 mm/10 s (n = 80). There is a statistical difference in paddle motion between fixed and flexible (p < 0.001), GE Senographe Essential and Hologic Selenia Dimensions paddles (p < 0.001). Paddle tilt in the medial-lateral plane is independent of time and varied from 0.04 ° to 0.69 °.
  
  
  CONCLUSIONS
  All machine/paddle combinations exhibited motion and tilting, and the extent varied with machine and paddle sizes and types.
  
  
  CONCLUSIONS
  This research suggests that image blurring will likely be clinically insignificant 4 s or more after the clamping phase commences.
authors.affiliation: 1 Directorate of Radiography, University of Salford, Salford, UK.
authors.forename: Wang Kei
authors.initials: WK
authors.lastname: Ma
authors.affiliation: 2 Discipline of Medical Radiation Science, Faculty of Health Sciences, University of Sydney, Australia.
authors.forename: Mark F
authors.initials: MF
authors.lastname: McEntee
authors.affiliation: 1 Directorate of Radiography, University of Salford, Salford, UK.
authors.forename: Claire
authors.initials: C
authors.lastname: Mercer
authors.affiliation: 3 Department of Radiography, Countess of Chester Hospital, Chester, UK.
authors.forename: Judith
authors.initials: J
authors.lastname: Kelly
authors.affiliation: 3 Department of Radiography, Countess of Chester Hospital, Chester, UK.
authors.forename: Sara
authors.initials: S
authors.lastname: Millington
authors.affiliation: 1 Directorate of Radiography, University of Salford, Salford, UK.|4 Karolinska Institute, Stockholm, Sweden.
authors.forename: Peter
authors.initials: P
authors.lastname: Hogg
mesh_terms: D003250:Constriction; D005260:Female; D006801:Humans; D008327:Mammography / Q000295:instrumentation*; D009038:Motion; D019047:Phantoms, Imaging