Eye dose limits and the use of overcouch and undercouch X-ray image intensifier systems.

Abstract

Over the past few years several papers have been published drawing attention to the possibility of increased radiation doses to staff when using fluoroscopy systems consisting of an overcouch X-ray tube and an undercouch image intensifier, rather than the reverse (Jacobson 1971; Stacey et al, 1974; Wholey, 1974; Hemmingson & Lofroth, 1978; Faulkner & Moores, 1982; Law, 1985). Several of these papers consider the question only in relation to cardiac catheterisation and coronary angiography. X-ray equipment consisting of overcouch X-ray tubes and undercouch intensifiers is being introduced increasingly into general-purpose fluoroscopy rooms and it is important that the radiological protection implications are examined: in particular, whether radiologists may have to be designated as classified persons by virtue of the eye doses they receive. One of the more recent papers on the subject (Faulkner & Moores, 1982) considers the use of such equipment for general purposes and includes details of dose rates occurring around over- and undercouch systems at waist and chest level. Recently, during the course of a radiological protection survey at a new hospital, we had occasion to carry out similar measurements and have obtained substantially different results for both arrangements. These are the results reported here.