After my mastectomy, I had regular mammograms and ultrasound which gradually got further apart over time - now 3D mammogram only annually. Other types of scan may depend on your diagnosis - but as far as I am aware an iron clad assurance that there is nothing more is not likely. Discuss with your oncologist what’s possible and helpful, but also consider the stress that scans can bring on. Good to have scans to settle any nagging concerns but most oncologists will be hesitant to recommend scans without a concrete something to look for. Best wishes for your next step.