HVAC Products for Magnetic Resonance Imaging (MRI) Applications
Magnetic resonance imaging (MRI) is an important diagnostic tool using powerful magnets, radio waves and computers to make detailed pictures of the inside of patient bodies. There are two major things that could disrupt the performance of the MRI machine or cause inaccurate results, including radio frequencies from outside areas and the presence of ferrous materials inside the MRI room.
Any ferrous material, or metals that contain iron and steel, placed too closely to the MRI machine can distort the very strong magnetic field produced by the MRI, which will result in errors in the MRI image.
While many nuts, screws, washers and bolts unavoidably contain ferrous material, they are generally too small to have an impact on the magnetic field. The danger with these smaller pieces is that they must be secured inside the room to prevent injury during the MRI. These materials, if unsecured, could fly to the magnet, endangering the patient.
Hospital design engineers must keep a critical eye out for any larger ferrous material near the magnetic field, including air distribution products that can typically include metal with iron and steel. Price Industries offers a variety of air outlet products that are safe for MRI applications.
Inside of the MRI room, there are two zones for the magnetic field: the 50 Gauss (5 mT) magnetic field and the 5 Gauss (0.5 mT) magnetic field. Refer to the image from Price Industries below to see the field depictions.
50 Gauss Magnetic Field: Based on a 1.5T magnet, the 50 Gauss (5 mT) field extends approximately 5’-8" radially around the MRI machine and 8’-2" axially out from the
machine. These dimensions are measured from the center of the magnet.
5 Gauss Magnetic Field: Based on a 1.5T magnet, the 5 Gauss (0.5 mT) field extends approximately 8’-2" radially around the machine and 13’-5" axially out from the machine. As above, these dimensions are measured from the center of the magnet.
Ideally, commercial HVAC products like air outlets, louvers, and ductwork should be installed outside the 50 Gauss magnetic field. However, if they must be installed inside that field, they should be made of non-ferrous material.
Outside the 50 Gauss field but inside the 5 Gauss field, it is recommended that air outlets and ducting be made of non-ferrous material like aluminum or 300 grade stainless steel. Conventional products may be allowed as long as the ferrous materials are properly anchored and arranged symmetrically around the magnetic field. Typically, however, all air distribution products are located outside the 5 Gauss field. Some Price Industries products may contain small amounts of ferrous material, but they are small enough that they shouldn’t interfere with the magnetic field and are anchored in the diffuser.
Some products currently available for MRI applications include:
- Aluminum square cone diffusers
- Aluminum square plaque diffusers
- Aluminum egg grate grilles
- Aluminum modular core diffusers
- Perforated supply diffusers
- Perforated return diffusers
- Aluminum louvered face return grilles
- Aluminum perforated face ceiling panels
It’s imperative to connect with your local manufacturer’s rep for assistance with product selection whenever you’re designing MRI rooms or any other medical-related projects. Sales engineers can assist with selection, submittals and more.
All blog content and images from Price Industries.
// about the author
Kelly Patterson is a lifelong learner and the marketing director at the Hoffman family of companies. There is nothing she likes more than talking about commercial HVAC systems and extraordinary customer service.