An x-ray table?

What is the big red button on the side of an x-ray table for and what is it called?
Thanx for the answers =)An x-ray table?
It is the Emergency Stop button.
"If the X-ray apparatus fails to cancel the radiation exposure, the operator must press the emergency stop button or switch bad the equipment at the mains isolator."
http://newton.ex.ac.uk/handbook/radlocal...
It is the EASY button. It is used to go and get help from Staples.
A big red button surrounded by anything is used to switch it on and off!
Emergency stop.