Keeping Zone III Secure:
Access Controls For MRI Suites.

By Tobias Gilk

One of the key components to the Safe Practice Guidelines as established by the American College of Radiology’s White Paper on MR Safety is securing Zone III. Zone III is the area outside of the magnet room which, either because of exposure to magnetic fields or simple proximity to the magnet, should be restricted to only trained MR personnel and successfully screened patients or visitors. Unfortunately, as is true with many of the Safe Practice Guidelines, individual facilities and credentialing bodies are too frequently ignoring this standard.

To protect the MRI equipment and, to a greater extent, the people in the suite, the 4-zone principle was established to tie access restrictions to hazards. In short, the more potential hazards in a space (culminating in the magnet room itself), the greater the access controls to get there. And since the risks aren’t limited to just the magnet room, access is to be restricted to areas outside of the magnet room, too.

Unfortunately there are many MRI suites that fail to provide these zones of access and appropriate access controls. Some believe that a deadbolt on the magnet room door is sufficient. While extra security for the magnet room is never a bad idea, it should not be provided in lieu of access controls for the Zone III area. Even beyond the notion that areas within the MRI suite should be controlled, there is the practical consideration of just how you provide access controls.

MR staff shouldn’t carry key chains around the department. Though most keys are only weakly ferromagnetic, the rings and fobs that hold them are frequently highly ferrous and risks in the magnet room. And just because a metallic object is small doesn’t mean that it isn’t a threat. Objects as small as nail clippers and bobby pins have caused patient injury in MRI suites, and a collection of just a few small barrettes, paper clips or other ferromagnetic items can throw off a magnet’s shim, costing 10’s of thousands of dollars to correct. Plus, after admonishing patients about the dangers of metal in the MRI suite, it is awfully bad form to whip out a key ring. So without conventional keyed locks, how do you secure areas within the MRI suite?

There are both electronic and mechanical combination locks, which don’t require keys. The problem in many facilities is that the combinations to these locks wind up circulated far wider than originally intended, which defeats the purpose of access control. Even when deployed with the best of intentions, too often the combinations wind up in the hands of security, transport, housekeeping, maintenance and other incidental staff that may or may not have appropriate MRI safety training. In fact, combination locks are discouraged for MRI suite access controls in the ACR White Paper on MR Safety.

Just as an MRI will erase the magnetic stripe on each of your credit cards, most magnetic swipe-card technologies will be rendered useless after the card is taken into the magnet room just once. At one client facility, the MR staff had a reputation for being anti-social because they refused to eat in the cafeteria, but it turned out that they didn’t go often simply because they couldn’t take advantage of the employee discount. The magnetic stripes on the back of their ID badges were erased daily.

So if facilities ought not use keys or combination locks, and can’t use magnetic swipe-locks, what other options does that leave?

There are a number of proximity (prox) cards which work through RF transponders that are both safe in the MR environment and not damaged by high-strength magnetic fields. There are also RF transponders in other sizes and shapes which are safe in MRI suites. RF transponder systems typically read the ‘key’ when momentarily held in front of a sensor pad, unlocking the door for a programmed length of time. These systems can be integrated with automatic door openers, lights, and any number of other control and assistance systems.

RF transponder systems also have the capacity to provide unique codes to each ‘key’ allowing individualized access controls, both by location or by time. For example, perhaps security has access to the MRI suite after hours, but not to the magnet room. Perhaps housekeeping staff can only have access to the MRI suite during hours of operation such that they are only there under the supervision of trained MR staff. Even more sophisticated systems can allow greater personalization and access controls through the use of fingerprint reading or other biometrics, but these can be both temperamental and very expensive.

These electronic keying systems can be installed at a single stand-alone location, or can be networked together providing centralized programming, monitoring and operation. These systems can be (and in many situations will be required to be) tied in with fire alarm systems or have simple mechanical overrides to guarantee exiting in situations of power outage or building alarm.

The physical mechanism to lock the door often comes in the form of an electric strike, an electronically-activated bolt, or magnetic locks. These systems can often be retrofitted to existing doors and frames, or can be incorporated, often invisibly, in newly installed doors. The specific selection of the locking device often must be made in conjunction with the keying system and in conformance to code mandated exiting requirements.

The simplest of these door control / access systems can cost as little as a few hundred dollars for a single point of access. Larger systems that tie facility-wide keying systems together throughout the building can reach much higher costs.

Every MRI facility with the slightest questions about their 4-Zone setup or the access controls they have installed should take this opportunity to review their suite. Since neither cost nor flexibility are significant roadblocks to implementing the access controls called for in the Safe Practice Guidelines, any shortcomings should be both easy to identify and quickly corrected.

If you would like assistance in reviewing your suite for compliance with the recommended ACR 4-Zone principles, please contact us and we would be happy to help you. Contact Robert Junk, AIA or Tobias Gilk for information on how we can help you with your current facility or your next MRI project.