The Effect of Low Pressure and Friction on High Energy X- and γ-Ray Radiography

Abstract

In high energy X- and γ-ray radiography, partial desensitized blotches frequently appear on developed films. The present work investigated the reason why desensitized blotches, which were thought to be due to low pressure on emulsion layers, appeared more frequently in high energy region of radiations than in low energy region below 300 kVp.
A simple apparatus to give pressure and friction to industrial X-ray films was manufactured, and various measurements about the pressure effect on radiography were carried out by using it. As the result it was found that the pressure effect was fairly different according to the kind of X-ray films, even if they had the same X-ray sensitivity, and had a dependency on energy of radiations. Futhermore, it was made clear that this effect showed a fading with the lapse of time.
It is concluded, therefore, that the high rate of appearance of desensitized blotches, which is considerably different according to the kind of films, is caused, both by the high energy of radiations used and by the use of relatively thick lead intensifying screens (0.5-2.0 mm) for such radiations.