title: What is the minimum amount of simulated breast movement required for visual detection of blurring? An exploratory investigation.
abstract: OBJECTIVE
  Image blurring in mammography can cause significant image degradation and interpretational problems. A potential source is due to paddle movement during image formation. Paddle movement has been shown to be as much as 1.5 mm. No study has yet been performed to determine how much motion would be noticeable visually. The aim of this study is to determine the minimum amount of simulated breast movement at which blurring can be detected visually.
  
  
  METHODS
  25 artefact-free mammogram images were selected. Mathematical simulation software was created to mimic the effect of blurring produced by breast movement during exposure. Motion simulation was imposed to 15 levels, from 0.1 to 1.5 mm stepping through 0.1 mm increments. 15 degraded images and 1 without blurring were de-identified, randomized and assessed on a blinded basis by two clinical experts to determine the presence or absence of blurring. Statistical testing was carried out to determine the consistency between the two observers.
  
  
  RESULTS
  The probability of simulated blurred image detection is the highest for the gaussian method and the lowest for soft-edged mask estimation.
  
  
  CONCLUSIONS
  The amount of simulated breast movement at which blurring can be detected visually for gaussian blur, hard-edge mask estimation and soft-edge mask estimation is 0.4, 0.8 and 0.7 mm, respectively. Cohen's kappa for all the levels of simulated blurring is 0.689 (p < 0.05).
  
  
  CONCLUSIONS
  This research establishes the concept of using probability to represent visual detection of blurring rather than defining a hard cut-off level.
authors.affiliation: 1 Directorate of Radiography, University of Salford, Salford, UK.
authors.forename: W K
authors.initials: WK
authors.lastname: Ma
authors.affiliation: 2 Directorate of Computer Science & Software Engineering, School of Computing, Science and Engineering, University of Salford, Salford, UK.
authors.forename: R
authors.initials: R
authors.lastname: Aspin
authors.affiliation: 3 Department of Radiography, Countess of Chester Hospital, Chester, UK.
authors.forename: J
authors.initials: J
authors.lastname: Kelly
authors.affiliation: 3 Department of Radiography, Countess of Chester Hospital, Chester, UK.
authors.forename: S
authors.initials: S
authors.lastname: Millington
authors.affiliation: 1 Directorate of Radiography, University of Salford, Salford, UK.
authors.forename: P
authors.initials: P
authors.lastname: Hogg
mesh_terms: D001940:Breast; D003198:Computer Simulation; D005260:Female; D006801:Humans; D008327:Mammography / Q000592:standards*; D009068:Movement; D015588:Observer Variation; D012984:Software