The fifteen mile ring around Dunwoody includes towns nobody drives from at 5pm
Radius targeting measures the wrong thing in a metro where the interstate decides who can get to you.
Draw a fifteen mile circle around most northern suburb addresses and it will swallow parts of three counties. Some of those areas feed you patients weekly. Others sit on the far side of a Perimeter interchange that nobody crosses voluntarily at the end of the workday.
Build the target list from named places instead: the towns and ZIP codes your patients actually come from, plus a short list of adjacent ones you want to test. Exclude the rest outright rather than letting the ring decide.
Watch the direction of travel too. A practice in Sandy Springs may draw easily from Dunwoody and Brookhaven and almost never from the other side of Cobb County, even though the map shows similar distances.
Check the location report every month and prune it. Areas that generate clicks and no booked visits are telling you something about the drive, and the fix is an exclusion, not a better ad.