Emergency Shut Down
Does the scanner have an emergency "stop" button?
|
|
Yes. In fact most facilities have two types of "Emergency Stop" buttons with different actions.
Emergency Shutdown: Does not quench the magnet but turns off most electrical power in the scanner room and operator area, including the console, computers, patient table, and anything on the UPS (uninterrupted power supply) circuitry. It may be a simple red button sometimes labeled with the confusing wording "Emergency Stop" or "Power Off". Emergency lighting is not affected and depending on system design and choices, there may be residual power to gradients and other devices in the equipment room. This switch should be used when there is a serious equipment fault or hazard, such as fire or water in the vicinity of the MR scanner.
Emergency Magnet Rundown Unit ("Quench Button"): The EMRU initiates a controlled quench and turns off the magnetic field. The electrical power remains on. Like the Emergency Shutdown ("Power Off" switch) the EMRU is often a big red button located on the external wall of the magnet room near the door. It may be labelled "Magnet Stop" or "Emergency Run Down". This button should only be used in a life-threatening emergency, such as a patient pinned in the scanner by a metal object or a fire in the magnet gantry.
Initiating an emergency quench is a serious proposition, placing the scanner out of service for a week or more, potentially damaging the magnet, and costing $30,000 or more to replace the lost liquid helium.
Initiating an emergency quench is a serious proposition, placing the scanner out of service for a week or more, potentially damaging the magnet, and costing $30,000 or more to replace the lost liquid helium.
|
Two types of Emergency Magnet Rundown Units.
(Left) A simple red button design manufactured by Phillips. When the red button is pushed, a controlled quench occurs within 2 minutes. (Right) A more complex EMRU that is part of an alarm system that monitors multiple parameters including helium level, pressure, and line voltage. The central red button produces a quench. |
References
MRI Safety Manual from UCLA's Ahmanson-Lovelace Brain Mapping Center (pdf). Revised September, 2012. One of the best research facility manuals I have seen, can also be obtained directly from this link. Discussion of emergency shutdown procedures can be found on pdf pages 12-17.
MRI Safety Manual from UCLA's Ahmanson-Lovelace Brain Mapping Center (pdf). Revised September, 2012. One of the best research facility manuals I have seen, can also be obtained directly from this link. Discussion of emergency shutdown procedures can be found on pdf pages 12-17.
Related Questions
What is a quench?
What is a quench?