Final answer:
The key concept in MRI safety is that the magnet is always on, which is vital to remember because the magnetic field can attract metal objects and cause injury or damage.
Step-by-step explanation:
The most important concept to remember about MRI safety is that the magnet is always on. It is crucial to recognize this because the magnetic field is very strong and can attract metal objects with significant force, which can cause injury or damage. Since the magnet is always active, even when the machine is not actively used for scanning, all objects and devices that may be affected by a magnetic field must be managed with this in mind. It is imperative that safety protocols be strictly followed to avoid accidents, including keeping metal objects and devices out of the MRI scan room unless they are confirmed to be MR safe or MR conditional.
For example, an MRI technician wearing a metal ring entering the magnetic field abruptly could experience an induced current in the ring due to the change in magnetic field strength. Depending on the metal and the strength of the field, this could potentially lead to heating of the metal item. This illustrates why being aware of the always-on state of the MRI magnet is crucial for preventing safety incidents. As the magnet's pull can be neither turned off nor easily controlled, safety procedures are designed to control the environment around it.