UNSCEAR DATA COLLECTIONS ON MEDICAL RADIATION EXPOSURES - TRENDS AND CONSEQUENCES

UNSCEAR evaluates medical radiation frequencies and effective doses (E) or effective dose equivalents (H-E) at four health care levels (I = industrialised countries, IV = poor developing countries). The 1993 Report is fairly complete for levers I and II. Effective doses for specific procedures may differ from effective dose equivalents by a factor of 2, but for entire practices E and H-E are similar. For most X ray examinations, doses at level I decrease but computed tomography (CT) doses are increasing, resulting in an overall annual per caput H-E of 1 mSv. Doses at levels II, In and IV are 0.1, 0.1 and 0.04 mSv (worldwide average 0.3 mSv). For nuclear medicine, the annual per caput H-E is 0.09, 0.008, 0.008 and 0.008 mSv at levels I-IV (worldwide average 0.03 mSv). For the first time, UNSCEAR now also estimates effective doses in radiotherapy (excluding dose to target). These are 0.7, 0.2, 0.03 and 0.02 mSv annually per caput at levels I-IV (average 0.3 mSv) for tele- and brachytherapy, much less for therapeutic nuclear medicine (average 0.002 mSv). These doses cannot be directly compared to diagnostic doses, but therapy should not be disregarded in dose statistics. UNSCEAR draws no radiation protection conclusions. However, its data suggest that attention should be paid to CT, to paediatric X ray examinations, to repeated X ray examinations of small subsets of populations, to fluoroscopy and to choice of diagnostic radiopharmaceuticals in developing countries.