While I agree with the general thrust of your comment, the machines used by the TSA are not "focused" in the same way. It would take much greater effort to create hazardous conditions like these patients experienced.
The TSA systems (at least the backscatter X-ray) do use a focussed moving beam to build up an image. They rely on the continual movement of the beam to limit the dose.
There are a number of safety systems to prevent the machine leaving the beam on should the mechanism stick.
And of course they are operated by the finest trained experts with a comprehensive background in nuclear physics and the ability to react in the fraction of a second before a notifiable dose was delivered
There are a number of safety systems to prevent the machine leaving the beam on should the mechanism stick.
And of course they are operated by the finest trained experts with a comprehensive background in nuclear physics and the ability to react in the fraction of a second before a notifiable dose was delivered