There are a few instances when Magnetic shielding may be required.
1. When the MRI’s 5G line or the FDA established safety line for pacemakers, etc., is not contained within a secured area.
2. When sensitive equipment outside the exam room needs to be protected from even the weakest outer edges of the MRI magnetic field.
3. When external magnetic fields such as low frequency (60 hz,) needs to be shielded away from the MRI magnet.
In cases number 1&2, the magnetic field lines which can be found in the MRI manufacturers planning guide need to be overlaid on the proposed suite layout. The safety rule states that any areas containing 5G or greater magnetic fields needs to be secured and posted with signage. In the event the 5G line extends outside the MRI exam room into adjacent spaces, public hallways, or outside the building where restricted access is not possible, or if magnetic fields are present in areas with sensitive equipment, then magnetic shielding is required.
The shielding process is achieved by using steel plates to “capture” the magnetic field. The exact quantity and geometry of the magnetic shield steel is precisely calculated and computer modeled on a site to site basis. Magnetic shielding can be needed on a section of wall, or the entire MRI exam room in various thicknesses.
It is also important to understand the impact of the magnetic shielding on the MRI magnet. Specific attention is required to the amount of steel used to achieve the desired shielding. It gets to a point where the magnetic shielding steel influences the MRI magnet and certain calibrations become impossible. In these situations, dramatic changes to the site layout may be required.
In case number 3, the environment around the outside of the MRI exam room needs to be evaluated for the presence of electromagnetic interference (EMI). Typically this is a 60hz magnetic field generated from high power areas such as electrical closets, large motors, power lines, etc. Sensitive measuring equipment is used to evaluate the site conditions and determine if magnetic shielding is required to protect the MRI scanner. The course of action depends on the measured levels of EMI. In most cases, shielding can remedy the situation.
We have trained individuals who will review and assist with all magnetic shielding needs.
Features / Advantages
We stock M-36 silicon steel to be used in magnetic shields. M-36 offers the ability to use less material to accomplish the same shielding. This results in less weight and cost.