Edward Muka

High-resolution, high-performance radiographic film scanner

In this paper, we discuss the requirenients, design approach, and features for a high-performance, laser-based radiographic film digitizer. The scanner is capable of digitizing a radiograph over a 3.5 diffuse density range in 15-30 seconds while not significantly reducing the noise-equivalent-quanta (NEQ) relative to the original analog screen-film image. Three resolutions are possible, corresponding to maximum film sizes of 35 x 43, 24 x 30, and 18 x 24 cm, with pixel sizes of 86, 59, and 43 microns; respectively. Preliminary results of side-by-side comparisons of scanned data reconstructed on pnnted film with the original analog film are discussed, along with future directions for research.

High-resolution teleradiology applications within the hospital

Many of the commercial applications for teleradiology have involved the transmission of reduced resolution x-ray images over modest bandwidth telecommunications lines for the purpose of making a preliminary diagnosis. In order to study the technical and operational requirements for future teleradiology applications, the authors have focused on the demanding requirements for teleradiology within the hospital and medical center. Applications within the hospital often require x-ray images of primary diagnostic quality transmitted with a minimum of delay. An experimental, high-resolution film scan/print system designed by Health Sciences Division, Eastman Kodak Company, has been developed for installation in a working clinical environment. Images scanned at a spatial resolution of 4K X 5K can be delivered over a fiber optic link to a laser film printer at a rate of two films per minute. Preliminary plans to install this device in a variety of clinical settings have led to rethinking the requirements for automatic film loading, film and patient identification, throughput requirements, and image display formats. As an initial implementation, and application is being developed which allows chest radiographs taken in the admission area to be interpreted at a remote site within the hospital. Images can be viewed on high resolution monitors, or film replicates can be produced on a nearby laser printer. Tight coupling with a radiology information system provides access to relevant diagnostic information including prior radiology reports, and prompt electronic reporting and signature can be accomplished.

Replication of diagnostic radiographs using a film scanning/printing system

Digital film scanning/printing systems which do not alter the diagnostic content of radiographs are required for diagnostic teleradiography, electronic image archiving, and image enhancement. Described is a high fidelity system capable of digitizing and reprinting films with minimal alteration of detail or degradation of noise for either general radiographs or mammograms. The system transfers resolution up to 10 lp/mm and has a useful density range of 0-3.5. Examples of chest, bone and breast films are presented.

Performance analysis of medical x-ray film digitizers

A system model for analyzing degradation in the image quality of a radiograph introduced by a film digitizer is presented. The analysis is an extension of the screen-film model of Shaw and VanMetter (SPIE 454, 128-141(1984)). By combining the screen-film characteristics for specific exam types with the properties (e.g., MTF and NPS) of a particular scanner design, the information transfer of the whole digital system can be determined. As an example, the performance of two typical film digitizers, a CCD-based scanner and a laser-based scanner, are evaluated and compared. Image quality descriptors, such as DQE and NEQ as well as equivalent bandwidth and system aperture, are used for the evaluation. By incorporating the human observers threshold response to changes in noise levels (just noticeable differences), a criterion for negligible loss of image information can be established. This can be very useful for system optimization and determination of design tradeoffs.