I have not had radiation yet but regardless migraines just come and go and if you have had migraines in the past you are likely to get different types down the rad..
Since my mid 20s I had started getting a migraine that mimics a stroke and has absolutely no pain involved
When having an attack of that particular type of migraine i will get 2 or more of these symptoms: half my face will droop, I will start to lose feeling in (and control off) half my body, I will have trouble speaking (and speak gibberish), I will, lose hand / eye coordination, if typing I will type gibberish (and not realise it - i will reread what was typed and not even register it is gibberish until the recipient returns my e-mail asking WTF? and the message will be just a bunch of random letters typed in what (in appearance) resembles words....
As i also have 2 cerebral anyrisams I am at a risk of having a stroke so as you cam imagine appearance of these symptoms sent me i a tail spin and had early on resulted in my visiting Emergency on many occasions...
How does one know that it is not a stroke - short of imaging the head at the time there is no way really - the difference is that my symptoms will eventually pass....
Several months after this started happening I was very fortunate to have had a senior neurosurgeon be asked to examine me in the Emergency (after I had been wheeled in 4 times in under 3 days) and what he had told me has worked so well i advise anyone suffering from migraines to do it.
What he said was that if in the early stages (ie when the very initial symptoms appear) I take 2 Paracetamol tables and darken the room and stay still within 20 minutes symptoms will ease up or dissapear altogether IF it is migraine as that dose of paracetamol taken early enough will resolve any migraine.
If the symptoms do not get better OR if they continue to worsen then i may have a reason to worry and need to call 000.
Offcourse it is a good idea to have someone stay with you as you take the paracetamol (jusst in case it is not a migraine and you become unable to make the phone call).
Do note that for this to work Paractamol needs to be taken at the 1st sign of symptoms (and not just when pain hits as by the time pain hits migraine may have progressed too much to be stopped so simply)
I know this may not help with your original question BUT if you do continue to suffer form that migraine i hope this may help you maybe manage the symptoms and relieve some of the worry and fear and prevent some of the trips to Emergency you may otherwise make
Hugs
Jel.