Image avoidance

Efforts should be made to avoid unnecessary patient exposure to imaging devices that use ionising radiation, according to a warning from the International Atomic Energy Agency. The Agency suggests that MRI and ultrasound should therefore be more widely used instead of X-ray based imaging.

Significant developments in medical imaging techniques has led to a surge in physicians scanning their patients for diseased tissue and other problems. One of the most commonly used techniques computed tomography (CT) delivers a relatively high dose of X-radiation to the patient. The IAEA says a single CT scan is equal to roughly 500 chest X-rays and has now issued a warning that such exposure could increase patients' lifetime risk of developing cancer, especially with repeat.

The IAEA is now working with other international organizations to improve patient protection and devising a Smart Card project that will log total radiation exposure for individuals. The development of X-ray machines and scanners that provide the radiation dose delivered in different examinations, as well as advances in electronic medical record systems, should eventually allow for this data to be included in medical records and on the electronic health cards already carried by many people in the developed world. The Smart Card concept was launched at a meeting in Vienna 27-29 April 2009.

"The medical application of ionizing radiation is the fastest growing source of radiation exposure to human beings today," explains Renate Czarwinski, Head of the IAEA's Radiation Safety and Monitoring Section. "We acknowledge the great value of the new technologies, but want to ensure that each and every examination is justified. The radiation protection of patients is also important."

The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), estimates that around four billion diagnostic X-ray examinations are carried out worldwide each year, which is an increase in exposure of almost a fifth over the past decade.

"A major concern at the moment is the growth in the number of CT scans being done around the world, especially in the developed countries," says Robert George, President of the International Society of Radiographers and Radiological Technologists (ISRRT). "The results and the benefits are so good that there's a tendency to overuse the technology."

Indeed, computed tomography provides three-dimensional views of internal organs, blood vessels, and other soft tissues. It produces very clear images, is easy to operate and causes little patient discomfort. However, magnetic resonance imaging, which involves no ionising radiation, could be used for many of the scans for which CT is used. Moreover, research published in the New England Journal of Medicine in November 2007, suggests almost half of all scans are questionable on the grounds of medical justification.

Improving patient protection requires a multi-pronged approach including new techniques and tools to reduce radiation doses, better dose management and, most importantly, greater awareness on the part of the patient and of the doctor prescribing the examinations, says the IAEA. This approach must also be balanced carefully against the benefits that a CT scan might bring in terms of disease detection.

One misconception among some health professionals regarding recent advances in CT scanning is that today, a scan may last no more than a minute, whereas a decade ago a scan took quarter of an hour. Practitioners assume this means less radiation exposure. However, the advances have been in the acquisition technology, which allows the same or greater radiation dose to be dispensed during a much shorter scan time and produce still clearer images.

Patient advocacy has a role to play and patients should ensure that they are fully informed of the justification of a CT scan as opposed to an alternative imaging approach, such as MRI, or an altogether different diagnostic appraisal. Nevertheless, radiologist Christian Herold at the Medical University of Vienna and President of the European Society of Radiology posits that are should be taken that such advocacy does not result in patients refusing necessary scans for fear of radiation exposure.

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.