I had a patient crashed on the CT table as well, and that was within 3 months of being put in the ED sat, and I only work 2 weekends per month. So yeah, it's pretty common.
The main reason is the PT who are sent to CT usually have some kind of serious condition. In my case, he had a GSU to the chest w/o exit wound, and an INR of 9 (botched suicide attempt). The ER doctor can tell he's bleeding internally but can't tell what/where's been nicked. The patient was fully responsive and stable on Neo + transfusion. With an INR of 9, groaping around inside blindly would be dicey, so he tried to get a quick CT.
But the patient went down hill really fast on the CT table. (blood reached a level in his pleural cavity to stop the heart). We had to abort the CT in the middle. No amount of epi could get his heart beating. and the physician was faced with let him die on the CT table, or crack his chest open to relieve the pressure (but knowing for sure that with his INR, he'll bleed out like a butchered pig). Well, he cracked his chest open on the CT table, heart came back on, but he was spilling blood everywhere. We where literally running him from CT to OR just like the movies. Never saw so much blood in my life and was dripping on my shoes as I help push the cart.
When we got to the OR, he had the faitest femoral pulse, but I have never seen a person so white before, white as a sheet of paper. The OR physician just mumbled "he's dead". And sure enough, he didn't make it out of there. His suicide attempt was successful I guess, just not he way he would have liked.