Measurements of the frequency distribution of optical density in screening mammography.
A method for obtaining histograms of the frequency of occurrence of optical densities in mammograms has been implemented. Averaged optical density distributions were produced for approximately 50 screening mammograms at each of two centres using different film-screen and processing chemistry combinations. Additional measurements were made on films of two commercially available anthropomorphic breast phantoms. The results show that screening mammograms, on average, exhibit a strongly peaked optical density distribution which corresponds closely to the target optical density measured using the current recommended test protocol for automatic exposure control devices.
Regional Medical Physics Department, Newcastle General Hospital, Newcastle-upon-Tyne, UK.
C J
CJ
Kotre
K J
KJ
Robson
K
K
Faulkner
D001943:Breast Neoplasms / Q000517:prevention & control*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008327:Mammography / Q000592:standards*; D008403:Mass Screening / Q000592:standards*; D008961:Models, Structural; D055095:Optics and Photonics; D011785:Quality Assurance, Health Care; D012016:Reference Values; D014963:X-Ray Intensifying Screens