British MR experts lobby against EU law

European Union legislation aimed at protecting workers from electromagnetic radiation has triggered a wave of protest among U.K. radiologists and MR researchers. They are urging government officials to support a scientific review of proposed exposure limits before the conservative figures become enshrined in national law.

The furor centers on the Physical Agents (Electromagnetic Fields) Directive, which passed the European Parliament last year (DI SCAN 06/02/04). The directive imposes strict maximum values for workers' exposure to electromagnetic radiation at frequencies up to 300 GHz. Patients' exposure to electromagnetic fields generated by clinical MR is not covered.

Objections to the directive's harsh limits were aired during its drafting. Certain concessions were won but not all that had been demanded. EU countries were then given until April 2008 to turn the legislation into national law.

Suggestions made at this year's U.K. Radiological Congress that the U.K. government would implement the legislation sooner rather than later have reawakened fears about the impact on MR and prompted an organized campaign of dissent. Critics are questioning the scientific validity of figures used by EU officials, which they say have resulted in unjustifiably cautious limits.

"We're asking for time," said MR pioneer Prof. Ian Young, a visiting professor of electrical and electronic engineering at Imperial College London. "What we need is a couple of hundred thousand pounds of funding and some medical statisticians to wade through the available data and show that the information is here already to justify changes to the directive."

The operation of MR scanners involves three distinct types of electromagnetic radiation: the magnet's static magnetic field, low-frequency gradient pulses, and high-frequency radiofrequency radiation. The current legislation places no restriction on exposure to static fields, although this is expected to be included in future revisions. Limits set for RF radiation, which can cause burns, are deemed fair. But thresholds for gradient pulses have been set so low that they will make certain clinical MR practices illegal, according to critics.

"The problems arise in two situations. One is where a patient is very ill, or a child has been sedated. It is not uncommon then for a member of staff to stand very close to the magnet," said Dr. Stephen Keevil, head of MR physics at St. Guys and St. Thomas's Hospitals in London. "The other is the emerging area of interventional MR, where surgeons may need to lean right into the scanner while imaging is in progress."

The directive's implementation would also preclude MR researchers from imaging themselves or nonpatient volunteers. This is a well-known practice during the development of new MR techniques and technology.

Concerns being aired in the U.K. are generally shared by the MR industry, said Hans Bursig, secretariat general of the European Coordination Committee of the Radiological, Electromedical, and IT Industries (COCIR). COCIR was among the groups that lobbied successfully for the static magnetic field limit to be excluded from the directive. Its request for MR to be exempt altogether from the legislation, however, was turned down.

"There has been no full assessment of the potential impact on the use of MR in medicine. In the absence of any evidence that MR is indeed harmful to workers, we therefore advocate an exemption of medical devices from the scope of the directive. However, this will be difficult to achieve, since it requires an amendment to the existing directive," Bursig said.

Georg Frese, MR standards and regulations managers for Siemens Medical Solutions, agrees that an exemption for MR is looking increasingly unlikely. Existing regulations in Germany limiting workers' exposure to electromagnetic fields currently include such a clause. This may need to be removed if Germany is to comply with the EU ruling.

"I still can't believe that this will really happen, and I am always optimistic that the politicians will recognize the flaw in this EU directive," Frese said. "When you talk to politicians, they all agree that MR is of considerable benefit to public health and should not be artificially hampered by restrictions. However, they have not yet been able to find a way to define an exemption for MR."

Full implementation of the directive should not require any changes to MR technology itself, said Hans Engels, MR safety director for Philips Medical Systems. MR is of proven clinical benefit, and limits set to protect patients from RF exposure or discomfort during exposure to switching fields are not being exceeded. Extra measures or guidance may be needed for MR workers involved in the development, installation, and maintenance of scanners.

"Technically, there is no need to change the specification of MR scanners. There is no clinical reason why we should do that, and at this moment, we do not plan to do that," Engels said.

Most clinical MR exams will be unaffected by the legislation. But practices common to interventional MR procedures will be compromised, Engels said.

"The question is, How important is interventional MR? At the moment, it is still a niche application, but there is a good chance that it will evolve and become more practical in the future," he said.

Approximately 40 to 50 dedicated interventional MR units have been installed worldwide to date. This figure, which includes both low- and high-field systems, is growing, according to Philips. The company also expects significant expansion in the market for MR-guided high-intensity focused ultrasound.

MR industry representatives are currently drafting international safety standards to enable legal enforcement of the EU directive, Engels said. EU member states are free to impose the new regulations in advance of these standards, but that is unlikely.

"I am hopeful that we will be able to come up with the right standards in 2007 or 2008. Before that, there is no need for a national law, because as long as you do not have an international standard, the law cannot be executed," he said.