UN: Medical imaging radiation is main source of rad exposure
The use of radiation in medicine accounts for most human exposure to ionizing radiation, according to a report issued by the United Nations (UN) scientific committee on the effects of atomic radiation.

“Medical exposures account for 98 percent 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,” the UN scientific committee on the effects of atomic radiation said in a summary of the report to the UN General Assembly.

The findings of the report, based on data collected from 1997 to 2007, showed that about 3.6 billion x-ray examinations were performed each year, an increase of more than 40 percent, or 1.1 billion, from the previous decade.

Between 1980 and 2006 in the U.S., medical exposure grew to levels comparable with natural background exposure, the report said. CT scans were the major contributor, with others being diagnostic x-rays, interventional procedures and nuclear medicine, according to the report.

The report defined four levels of healthcare. In the highest, level one, based on the number of physicians per capita in the population, medical x-ray examinations are 65 times more frequent than in level three and four countries with the lowest ratio of physicians per capita. The report also noted that as techniques developed and their use widened, medical uses of radiation continued to increase irrespective of the level of healthcare being delivered.

According to the report, exposure to natural sources of radiation included: inhalation of the naturally occurring radioactive radon gas, which accounted for about half the average exposure to natural sources of radiation; cosmic radiation; ingestion of naturally-occurring radioactive elements in food and water; and external irradiation from naturally-occurring radioactive elements in the soil.