Medical exposures account for 98 per cent of the contribution from all artificial sources and are now the second largest contributor to the population dose worldwide, representing approximately 20 percent of the total. About 3.6 billion medical radiation procedures were performed annually during the 1997-2007 period, which represents an increase of 1.1 billion procedures compared with previous period (1991-1996). The distribution of medical procedures and of doses is markedly uneven among country groups. Almost 75 percent of the worldwide collective effective dose due to medical exposures is accounted for by health-care level I countries (those that are relatively more developed).
Taking into account the same periods, the total number of diagnostic medical examinations, both medical and dental, is estimated to has risen from 2.4 billion to 3.6 billion – an increase of approximately 50%. Such examinations were over 65 times more frequent in level I countries (which account for 24 % of the global population) than in level III and IV countries (which account for 27% of the global population). The wide imbalance in health-care provision is also reflected in the availability of X-ray equipment and of physicians.
As part of that trend, new, high-dose X-ray technology (particularly computed tomography scanning) is causing extremely rapid growth in the annual number of procedures performed in many countries and, by extension, a marked increase in collective doses. For several countries, this has resulted, for the first time in history, in a situation where the annual collective and per caput doses of ionizing radiation due to diagnostic radiology have exceeded those from the previously largest source (natural background radiation).
An estimated 32.7 million diagnostic nuclear medicine examinations are presently performed annually worldwide, which represents an increase of 0.2 million examinations per year or under 1 per cent since the 1991-1996 period. Over that same period, the collective effective dose due to nuclear medicine examinations increases about 35%. People living in health-care level I countries account for about 90 percent of all nuclear medicine examinations.
Level I countries accounted for about 70 percent of all radiotherapy treatments. An estimated 5.1 million courses of radiotherapy treatment were administered annually between 1997 and 2007, up from an estimated 4.3 million in 1988. About 4.7 million of those treatments involved teletherapy and 0.4 million brachytherapy.
More information could be found in the following documents and links:
• UN Fifty-sixth session (10-18 July 2008). Report of the United Nations Scientific Committee on the Effects of Atomic Radiation