How is the magnetic field of an MRI contained?

The magnetic field of an MRI is contained using both passive and active shielding techniques, which work together to minimize the magnetic field's influence on surrounding areas and ensure patient and staff safety.

Passive shielding involves the use of materials with high magnetic permeability, such as iron, which are placed around the MRI magnet. These materials help to absorb and redirect the magnetic field lines, effectively reducing the external magnetic field strength and limiting its reach. This type of shielding is typically built into the structure of the MRI room.

Active shielding, on the other hand, employs electromagnetic coils strategically positioned around the magnet to create a counteracting magnetic field. This counter-field dynamically adjusts based on the strength and direction of the magnetic field produced by the MRI machine. By actively managing the magnetic field, this method enhances the containment of the magnetic effects and further minimizes stray fields outside the MRI system.

The combination of both shielding methods leads to a more effective containment strategy. Passive shielding takes care of the bulk of field containment, while active shielding provides precision and adaptability, ensuring that the MRI environment remains safe for patients and healthcare professionals. This multifaceted approach is why the correct answer encompasses both passive and active shielding.