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.