The steady increase in the number of computed tomography (CT) scanners in the UK and elsewhere, together with their relatively high levels of patient irradiation, ensure that CT examinations are now a major contributor to the collective dose from medical radiology. A method has been developed to allow the assessment of dose to radiosensitive organs for the peculiar exposure conditions characteristic of a range of common models of scanner. This approach is based on normalised dose data derived for a mathematical anthropomorphic phantom using Monte Carlo techniques, complemented by measurements with thermoluminescence dosemeters of the absorbed dose free-in-air on the axes of rotation of the scanners. Such scanner-specific data may be used to interpret scanning protocols for particular CT procedures in terms of patient dose. The method has been implemented during national surveys in several European countries and data typical of UK CT practice are presented.