Letrazole was originally used to treat bone mets, it's now used more widely to try to prevent metastasis in the first place. So, you are probably taking the right drug regardless of what effect the radiotherapy had. Scans are a double edged sword and seem to be more commonly applied to those with private health cover. That's a pretty cynical viewpoint, but seems to be true. If the scan shows all clear, you will still be taking the AI. I know some people have more frequent tests, but the advice to listen to your body and report any changes is sound.
You can probably demand another scan, but they are not good for you, and if they show that the spots are still there nothing is likely to change much anyway. This stuff is hard to get your head around. If you are really stressed about it, restart the conversation either with your existing oncologist or find a new one.