My mom has non union scaphoid fracture. dr said 60 percent success after surgery. then he wants to do ct on her wrist every 3 months. is it way too much radiation? thanks ?

The imaging would be only to confirm healing. If it has not healed in 6 months or so, then there would be no point for continued imaging. You need to take into account the 60% chance of success through surgery. You may wish to consult a rehabilitation specialist to explore alternative ways to treat, e. g. electrical stimulation. For info: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2762246/