PET Scan

Here is some information that I think you'll find helpful.  I hope this answers your question. 

I don't think it can trace tumores inside your bone, Ct would probably do so.A PET scan demonstrates the biological function of the body before anatomical changes take place, while the CT scan provides information about the body's anatomy such as size, shape and location. Currently, PET scans are most commonly used to detect cancer, heart problems (such as coronary artery disease and damage to the heart following a heart attack), brain disorders (including brain tumors, memory disorders, seizures) and other central nervous system disorders.

PET scan is a unique type of imaging test that helps doctors see how the organs and tissues inside your body.

I don't think so. Ask your doctor to explain just what it is, and what it can and can not detect. This should have been explained to you so you know what the doctor is lqooking for.Ask him the questions when in doubt about something, so it will be clear in your mind what will be happening. Good luck.