ABSTRACT
RATIONALE AND OBJECTIVES: Any given mammographic film will exhibit changes in sensitometric response and image resolution as processing variables are altered. Developer type, immersion time, and temperature have been shown to affect the contrast of the mammographic image and thus lesion visibility. The authors evaluated the effect of altering processing variables, including film type, developer type, and immersion time, on the visibility of masses, fibrils, and speaks in a standard mammographic phantom. MATERIALS AND METHODS: Images of a phantom obtained with two screen types (Kodak Min-R and Fuji) and five film types (Kodak Min-R M, Min-R E, Min-R H; Fuji UM-MA HC, and DuPont Microvision-C) were processed with five different developer chemicals (Autex SE, DuPont HSD, Kodak RP, Picker 3-7-90, and White Mountain) at four different immersion times (24, 30, 36, and 46 seconds). Processor chemical activity was monitored with sensitometric strips, and developer temperatures were continuously measured. The film images were reviewed by two board-certified radiologists and two physicists with expertise in mammography quality control and were scored based on the visibility of calcifications, masses, and fibrils. RESULTS: Although the differences in the absolute scores were not large, the Kodak Min-R M and Fuji films exhibited the highest scores, and images developed in White Mountain and Autex chemicals exhibited the highest scores. CONCLUSION: For any film, several processing chemicals may be used to produce images of similar quality. Extended processing may no longer be necessary.
Subject(s)
Mammography/methods , Radiographic Image Enhancement/methods , Absorptiometry, Photon , Breast Diseases/diagnostic imaging , Female , Humans , Immersion , Mammography/instrumentation , Observer Variation , Phantoms, Imaging , Quality Control , Radiographic Image Enhancement/instrumentation , Solutions/chemistry , Temperature , Time Factors , X-Ray Film , X-Ray Intensifying ScreensABSTRACT
A small, externally occulted Lyot-type coronagraph, designed for use in the seventh unmanned Orbiting Solar Observatory (OSO-7), is described. Optical configuration, suppression of stray light, SEC vidicon detector, and data system are discussed, as well as integration of the instrument into the spacecraft and operation in orbit. Orbital operation produced daily images of the white light corona, from 2.8 to 10 solar radii, at least once per day for 2(3/4) yr. The first records of white light coronal transient events were obtained, and the corona was shown to be constantly changing.