BioEd Online

Doctors across Europe are complaining loudly about new regulations on radiation exposure, which they say will needlessly hinder their use of magnetic resonance imaging (MRI) when treating patients.

The European Union Physical Agents Directive, set to become law in April 2008, is aimed at protecting workers in telecommunications and the electricity industry from possible health risks caused by exposure to electromagnetic radiation.

Strong fields can induce a current within tissues, which heats them up and may cause damage. Some controversial studies have suggested that such fields may also damage DNA.

But the rules will also keep doctors away from MRI machines, which are another source of electromagnetic radiation. This will prevent nervous patients from being accompanied during scans, and may even restrict proper cleaning of the devices.

Slim evidence

Doctors say that MRI scanners are not dangerous, and that although the electromagnetic frequencies from these devices can gently heat tissues and stimulate nerves in the spine, this does not lead to damage because the heating effects are miniscule.

Peter Mansfield, a retired Nobel Prize winner who played a key role in developing MRI, says the regulations are detrimental and "should be sent back to the drawing board".

He and others note that MRI scans have been used to see inside the human body since the beginning of the 1980s, with no known ill effects.

Any firm evidence of adverse effects from standing next to a scanner is sparse, says Ian Young, a retired engineer who helped to build the first MR scanner for medical imaging. He adds that unpublished conference abstracts may have fuelled the directive and the advisory guidelines that precede it.

Michael Clark, a scientist at the Health Protection Agency in the UK, says the directive is designed to protect workers. He admits that doctors are right to point out the lack of clear evidence of harmful effects, but says: "We are dealing with a new technology and perhaps a bit of caution is necessary". "We can't rule out any long-term effect," he warns.

The directive will turn the UK's current advisory guidelines into law. These guidelines are based on the advice of the International Commission on Non-ionizing Radiation Protection and the National Radiological Protection Board. Researchers say these guidelines are also strict, but few people have complained as they are only voluntary.

Worst afflicted

The patients most affected by the changes will probably be anxious children and patients requiring specialized heart investigations. In the absence of a comforting hand, scared children may undergo more harmful but less intimidating X-ray imaging. And nervous patients may have to be anaesthetized before being scanned, subjecting them to an unnecessary risk.

Certain heart procedures may also face difficulties. In cardiac catherization, for example, a doctor uses an MRI scan to help guide a tube up the patient's leg to their heart. This would not be possible if the doctor was not allowed in the scanning room.

Cleaning the magnet will also be a problem, as technicians will no longer be allowed to get near the magnet. Steve Keevil, a leading expert in MRI-guided cardiac interventions at Guy's, Kings and St Thomas' School of Medicine in London, says technicians have been advised to clean the magnet with a sponge on a stick. Given the risk of superbugs, Keevil is horrified at this prospect. "It just doesn't wash."

Several leading experts in the UK have written to the Secretary of State for Health, requesting two years to do research that will justify relaxing the limits in the directive.