Radiology, Vol 146, 801-806, Copyright © 1983 by Radiological Society of North America
Evaluation of cassette performance: physical factors affecting patient exposure and image contrast
RA Schmidt, HP Chan, Y Kodera, K Doi and CT Chen
Physical properties of four radiographic cassettes were investigated in
combination with various screen/film systems. These properties included (a)
transmittance of monoenergetic x rays over 14-96 keV and comparison with
predictions based on attenuation coefficients; (b) relative patient
exposure from 60 to 120 kV (from phantom measurements) and correlation with
predictions based on measured transmittance as well as average energies and
angles of incident radiation; and (c) amounts of scatter from various
cassette materials and comparison with Monte Carlo calculations. The
results provide a model of performance based on quantitation of cassette
effects on system speed and image contrast. Carbon-fiber cassettes required
the lowest patient exposure, produced the least scatter, and (in
low-scatter situations) were capable of increased image contrast.
