If it's an advanced hospital in a big city, it's tolerable to do CT more times if necessary. Although the equipment is advanced, if it's an old machine in a small hospital or even equipment eliminated in a big hospital ... it's nothing, but the radiation will definitely be bigger. However, PET-CT (yes, not ptct) generally does not do much, because it needs to develop a little radioactivity (don't worry, it is also within the normal measurement range).