Why the x-ray machine adopts the secondary exposure hand switch

Do you know why the X-ray machine adopts the secondary exposure hand switch? Today, the editor will popularize the knowledge of exposed hand switch products. It is best to use an electronic circuit. In fact, this is the X-ray machine exposure hand switch control circuit that changes the exposure hand switch of the wireless remote control, so that the radiation personnel will have less contact with the wireless remote control switch. The receiver outputs a switch to control the two switches in the machine. The two switches are divided into two consecutive stages.
So why does the x-ray machine use a secondary exposure hand switch?
1. False trigger, reduce the damage of X-ray to the human body.
2. It has a reminder function, (exposure preparation)
The first stage, preheating the tube, increasing the speed
Second level exposure