Blurring in Radiography

Abstract

The various types of blurring occurring in radiography are examined. Experimental work was carried out by photometering density curves of a sharp edge and the densities were converted to exposures. For the case of screen blurring an exponential function was found to fit experimental results very well. The screen blurring can thus be specified by a single constant which is evaluated for a number of British screens. A mathematical expression is derived for curves representing composite blurrings and checked experimentally, giving again very good agreement. The problem of measuring blurring is dealt with and a method, based on area, is suggested. This is compared with methods suggested by other writers.