Midori Yoshida and Eiichi Honda
Medical exposure is increasing year by year. The main reason is an increase in CT examinations. X-ray examination has been shifting from conventional radiography to CT imaging. Although CT examinations account for only 7.9% of the total number of diagnostic medical examinations, the contribution is about 47% of the total collective effective dose due to diagnostic medical radiology in health-care level I countries according to the 1997-2007 survey by UNSCEAR. Dental X-ray examinations have hardly contributed it, but CT examination is indispensable in dentistry. Dentists also should follow the requirements for CT imaging by the
ICRP recommendation and review CT imaging protocol based on national diagnostic reference level (DRL).
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