Looking at your x-ray it looks like your lower right might have one. Maybe lower left too. I'll have a look at your CT later and have a proper look. But bear in mind they are simply my opinions only. Sometimes cavitations are obvious from x-ray, other times like my own they barely show up at all. So are easy to miss.
As for when do to surgery. There is no 'best' guide as to when to do them. Unfortunately proper research in this area is lacking. Personally I'd have them all done in one go, simply to get it out the way with. Although that might be less than ideal for some people. You still gotta eat !
Yes that is my website :) The name caviscan is actually for my commercial project. Been working on a replacement for the cavitat scanner for some time now. A working prototype is pretty close to being finished.