Photodensitometer measurements of images on radiographs

An x-ray photodensitometer provided accurate and precise measurements of linear dimensions on radiograph images. These measurements helped to infer the hidden dimensions of objects radiographed. A goal was to achieve an accuracy of +-25 μm. The recorded accuracy did not measure up to the precision, which, under favorable conditions, was +-25 μm. Systematic errors caused the errors in absolute value to be considerably higher in some cases. To satisfy this, auxiliary calibrations were made. Many deterrents to successful measurement arose. These included film grain noise, excessive density range and edge penetration, blurring, interfering structures, and scattered radiation. Film grain noise, in particular, limited the resolution of small details (fine structure) in a radiograph. Because of so many deterrents, the applicability of the measurement method used appears quite limited