Ferromagnetic detection at the magnet room door
An MRI magnet is always on, and a ferromagnetic object carried into the fringe field becomes a projectile. Our detection system provides a last technical check at the Zone III to Zone IV boundary, supplementing the screening procedure rather than replacing it.
Detection principle
- Passive magnetometry — senses distortion of the ambient magnetic field
- Emits no field of its own, so it cannot interfere with imaging
- Responds only to ferromagnetic material, not to aluminium, titanium or coins
- Detects material in motion through the sensing region
Sensing & discrimination
- Vertical magnetometer array for consistent coverage floor to head height
- Approximate height of the detected object indicated
- Signal processing to reject ambient noise — lift motors, corridor traffic, door mechanisms and building steel
- Adjustable sensitivity threshold to balance detection against nuisance alarms
Alarm & indication
- Visual and audible alarm on detection
- Clear at-a-glance status readable under stress
- Self-test and calibration so faults are visible rather than silent
Installation & integration
- Sited at the Zone III to Zone IV boundary, at the magnet room entrance
- Electronics designed to operate within the magnet fringe field
- Interfacing to door interlocks, access control and event logging
- Siting guidance to keep the unit clear of moving building metal
Scope & limitations
- Supplements screening, questionnaires, zoning and staff training
- Detects moving ferromagnetic material, not stationary objects
- Does not characterise implants — implant screening remains a documented questioning process
- Indicates that ferromagnetic mass is present, not what the object is
Working on MRI safety instrumentation?
We develop ferromagnetic sensing and MRI subsystem electronics, including couch control and operator interfacing.
Talk to our team