Daniel James Mickewich

The image quality characteristics of a novel ultra-high-resolution film/screen system

A film/screen system is described where the light emission of the intensifying screen is in the ultraviolet (UV), which is more efficiently absorbed by the film, and hence print-through is virtually eliminated. In addition, because of significantly higher UV absorption within the screen, the modulation transfer function is superior to that of conventional systems based on visible light. Thus the overall UV film/screen system has superior imaging efficiency and quality, as measured by the detective quantum efficiency and the noise equivalent quantum efficiency to those of conventional systems. These imaging characteristics of the novel systems are described and are compared with those of some conventional systems.

High contrast by imagewise iodide infection in a mixed silver halide system

High contrast photographic images suitable for lithographic use are obtained with stable (nonlithographic) developers when iodide is released from a surface-sensitized iodobromide emulsion to induce development of the exposed areas in an internally sensitized core-shell emulsion. A bromoiodide or trihalide core is produced by balanced double jet precipitation, then the core is chemically sensitized and covered with a chlorobromide or chloride shell by balanced double jet precipitation or preferably by a cyclic pAg addition technique. The core-shell emulsion must have a sensitivity equal to or greater than the surface sensitized emulsion.

Application of neural networks to computer-aided pathology detection in mammography

Digitized mammograms are used as input to a system of feedforward neural networks for determining the presence of clusters of microcalcifications. Rather than presenting the locations of detected suspected pathologies on the digital image itself, the intent is to produce a transparent overlay marking these possible pathologies for later diagnosis by the radiologist. Current results indicate that this method will in general be more efficient than human observers in locating low contrast objects and clusters of small microcalcifications (down to 50 micron diameter).

Image quality characteristics of a high-speed film-screen system based on Ultra-Vision technology

A 600-speed system based on Ultra-VisionTM technology has been designed. Since the undoped yttrium tantalate phosphore used in other Ultra-VisionTM screens is incapable of achieving the required speed with existing films it was necessary to admix a small fraction of lanthanum oxybromide which is a more efficient x-ray to light converter and which emits both visible (approximately 470 nm) and UV (approximately 370 nm) light. The image quality performance of the resulting system approaches that of conventional 400-speed film/screen systems. These image quality characteristics are described and compared with those of conventional 600-speed and 400-speed systems.