Radiology, Vol 145, 179-185, Copyright © 1982 by Radiological Society of North America
The influence of modulation transfer function shape on computed tomographic image quality
PM Joseph and CD Stockham
The influence of modulation transfer function (MTF) shape on computed
tomographic (CT) image quality was studied by computer simulation of a
recently proposed x-ray detector with a nonuniform, shaped response to
radiation. The shaped detector, while maintaining a high value of limiting
spatial resolution, was shown to depress MTF and signal-to- noise ratio
values at moderate spatial frequencies. This led to a significant loss of
sharpness on noise-free images. Despite a superior radiation dose capture
efficiency in the shaped detector, the MTF suppression was shown to produce
inferior visibility of 1.0-mm objects in an image with typical CT noise.
The significance for clinical imaging of the MTF suppression was
demonstrated using a scan of a human head. The implication is that better
methods than those currently used are needed for evaluating CT image
quality.
