The International Atomic Energy Agency has launched an effort to create a running total of how much medical radiation patients are exposed to over time by issuing smart cards and modifying electronic medical records.

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IAEA safety experts note that tracking dose for patients would provide a level of protection already available to medical practititioners. Standard protocols already exist to monitor levels of ionizing radiation that radiologists, technologists, and nursing staff are exposed to over prolonged periods.

The wearing of film badge or thermoluminescent dosimeters for several weeks or months is common practice. No such efforts, however, are made to record the cumulative x-ray dose received by patients.

The IAEA initiative attempts to redress this lack. Imaging equipment vendors and IT specialists are being brought together to develop a way of making patients' lifetime x-ray exposure available whenever and wherever they go for a scan. It is hoped that the dose data could eventually be stored on electronic health cards.

"What we want, essentially, is a long-term record of each patient's radiation exposure, whether on a card or in an e-healthcare system," said IAEA radiation safety specialist Madan Rehani.

The policy, announced April 29, was spurred in part by the growing popularity of diagnostic imaging exams that expose patients to ionizing radiation. As many as four billion diagnostic x-ray examinations will be performed around the world this year, according to the United Nations Scientific Committee on the Effects of Atomic Radiation. Utilization in all countries has risen more than 17% in the past 10 years.

All modalities that use ionizing radiation would have to display the dose delivered to patients in a standardized format to implement the IAEA's ambitious tracking proposal. Hospitals and clinics would also need an EMR system that can store the dose data for each patient and produce a running total of lifetime x-ray exposure.

Tangible results from the project, which is being funded jointly by the IAEA and the U.S. Nuclear Regulatory Commission, can be expected within the next three to five years, Rehani said.

Madan Rehani of the IAEA

Questions remain about the impact dose data might have on imaging referrals. The IAEA has no plans to set limits on cumulative exposure; patients with a high dose history should not fear exclusion from the radiology department. Instead, IAEA officials want physicians to think twice when sending patients for a CT scan or fluoroscopy procedure and to ensure that the dose is kept "as low as reasonably achievable."

"The medical application of ionizing radiation is the fastest growing source of radiation exposure to human beings today," said Renate Czarwinski, head of the IAEA's radiation safety and monitoring section. "We acknowledge the great value of the new technologies, but we want to ensure that each and every examination is justified."

Once patients have access to their dose records, they are more likely to challenge the need for imaging exams they are asked to undergo, said Dr. Donald Frush, a professor of radiology and pediatrics at Duke University Medical Center. This will give radiologists a chance to talk through the reasons for a study and explain how the risks will be minimized.

"I look at this as a positive step that improves healthcare, that improves the safety of patients," he said. "I encourage patients to ask these questions."

The inclusion of lifetime dose histories in health records could also help clarify the link between diagnostic imaging and the development of cancer. Although the biological damage done by high levels of ionizing radiation is well known, the impact of relatively low x-ray doses on human health is far less well understood, Frush said.