Diagnostic x-rays are the leading m...

Diagnostic x-rays are the leading man-made source of radiation aspect accounting for about 14 percent of all radiation exposing s worldwide. Although the risk of inducing cancer is believed to be small, the large number of patients expos to x-rays means that a significant number of cancers in the population could be attributable to these diagnostic criterions Berrington de Gonzalez and Darby estimated the cumulative risk of inducing cancers at different sites associated with customary radiologic investigations.

They used data from 15 countries to bring to maturity statistical models relating cumulative x-ray dose to nine frequent cancers. Data used in the studious mood included surveys of the commonness and types of x-ray studies undertaken in the countries studied, cancer statistics, and studies of the organ-specific radiation dose associated with the specific tests

The highest organ-specific radiation dose estimated was 44 mGy delivered to the thyroid during comput tomographic (CT) examinations of the cervical spine. CT of the chest was associated with more than 20 mGy to the breast, lung and esophagus. Similarly, CT of the pelvis expos the bladder to 23 mGy and imaging of the abdomen was associated with 22 mGy to the stomach. Coronary managements such as angiography and catheterization were associated with high radiation prospects to the lungs (more than 37 mGy) thyroid (25 mGy) and esophagus (1379 mGy) The researchers calculated average age- and sex-specific radiation doses for each major organ in each of the participating countries. These data were correlated with nine for the use of all cancer types to calculate site-specific radiation-induced cancer risks.

The researchers estimate that diagnostic radiology causes 5695 cancers in Americans younger than 75 each year. These attributable cancers are predominately colon bladder, and breast cancer, and leukemia. The risk is powerfully age related, beginning to rise at about age 40 and still increasing at 70 years of age. CT was associated with the largest number of induced cancers, followed by means of barium enemas, and x-rays of the hip and pelvis. Diagnostic x-rays could cause about 1 percent of U cancers, approximately double the attributed rate in 1981

ANNE D WALLING, MD

Berrington de Gonzalez A, Darby s Risk of cancer from diagnostic x-rays: estimates for the UK and 14 other countries. Lancet January 31 2004;363:345-51

EDITOR'S NOTE: The tables in this inquiry make sobering reading, especially those relating radiation outlook from CT studies. The bladder and colon appear to be particularly sensitive to the oncogenic results of radiation, especially in older patients. Although the risks to patients are small, this application of mind emphasizes the need for commonsense in ordering any radiologic close attention and attention to potential long-term risks, as well as short-term diagnostic gains.--A.D.W.

COPYRIGHT 2004 American Academy of Family Physicians

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