I disagree with your emphasis of "hospitals", because I think of hospitals as much more dangerous and threatening than airports. Your odds per visit of being killed by hospital-acquired infections alone are hugely greater than all forms of death caused by air travel.
I emphasis that not because I think hospitals are particularly safe but because I think the damage a malfunctioning x-ray machine may cause has a higher chance of being recognized for what it is in a hospital.
At the very least, people in hospitals tend to stay there longer. The radiation burns from Therac-25 took up to several days to become visible. Any damage that these machines may cause is likely going to be much more subtle, making the situation even worse.
I really hope you aren't being sarcastic, as that would be funnier. Here's how to make an x-ray machine strong enough to work with standard film that you can plug in the wall and uses old tv parts. Be careful in doing this as dosimeters apparently are required. http://www.belljar.net/xray.htm
