THE INCREASING IMPORTANCE OF X-RAY COMPUTED-TOMOGRAPHY AS A SOURCE OFMEDICAL EXPOSURE

Computed tomography (CT) has continued to expand steadily throughout t he world since the technique was introduced into clinical practice in 1972. It has, of course, made a substantial impact on patient care, al though national surveys have established the increasing importance of CT as a source of medical exposure. Information for the UK in 1993 sug gests that the contribution from CT to collective dose from X rays may have risen to about a third. It is essential that there should be a c ontinuing review of CT practice so as to rake advantage of all opportu nities for reducing exposure without loss of benefit to patients. A su rvey in the UK has indicated potential scope for improvement in the op timisation of protection for patients undergoing CT examinations and t he National Radiological Protection Board has made general recommendat ions aimed at ensuring better control of patient dose and, in particul ar, advocating the development of reference doses for CT.