1994 Volume 50 Issue 10 Pages 1716-1725
The purpose of this paper is to analyze the characteristics of scattered X-rays from a square-wave chart in terms of Monte Carlo simulation study and actual measurements employing a non-screen film system. It was confirmed quantitatively from the simulation study that there exist scattered X-rays from both of the lucite and lead plate, along with L-characteristic X-rays from the lead plate in the chart. The lead mask (4mm width) on the chart could not eliminate the scattered X-ray completely. The difference in square wave response observed with and without the lead mask was about 2%. The scattered rays from the chart was able to be eliminated by the air gap method with a 15cm distance between the chart and film. In an actual MTF measurement for screen/film systems, it is considered that the effect of these scattered rays is almost negligible; however, it is required to be careful to scattered rays and L-characteristic X-rays.
