Hi Mr Midget (or Ms 'cos we can do that now!). Do you mean your wife is experiencing anxiety in the run up to her scan, 'scanxiety', or anxiety in general?
I would start with your GP. They are able to diagnose anxiety reasonably simply. From there you can get a mental health care plan from the GP and a referral to a psychologist. The GP can prescrible drugs to assist in the short term but in the long run, my understanding is that anxiety is controlled with lifestyle and behavioural modifications. Meditation, mindfulness, exercise, cognitive behavioural therapy, stuff like that.
If the anxiety is breast cancer specific it can be worthwhile getting a therapist recommendation from you oncologist and/or breast care nurse. They might know someone who specialises in the field. There are also community based counsellors who charge very little to nothing.
I have a particular back story (don't we all?!), and getting BC exacerbated the anxiety that I had experienced, unbeknownst to me, all my life. It was diagnosed and managed for the first time in my life, a great relief. Since my BC diagnosis I have also been diagnosed with and treated for depression for the first time in my life. 50% of people diagnosed with breast cancer will develop depression, most usually after active treatment is finished. The emotional repercussions of a breast cancer diagnosis are so similar to PTSD that they're studying whether there can be lessons to be learned from the latter in treating the former.
So if it's any consolation, your wife is pretty 'normal'! I hope things improve for her soon, and that her scans are all good. K xox