You haven't mentioned the type of radiation so I will give you both scenarios:

IMRT:

The c-arm is done usually just after the mask fitting to set up preliminary site lines for the radiation beams in relation to the mask geometry. It is called that because it is in the shape of a "C" and can mimic the movement of a LINAC. It's just a specialized x-ray machine (they are used for other applications as well and can even be portable on wheels). I am not sure if they do the C-arm for XRT. Here is a link to a fairly technical article on the C-arm:

http://www.ece.jhu.edu/Seminars/Ramamurthi%20Defense.htm

If she is getting IMRT she will definitely get a CT as part of the programming protocol. They usually also do a 3 week CT to see how the response is and make tweaks in the programming if necessary.

Simulation is done just prior to starting actual radiation. They put you on the table, in the mask, and do a dry run to insure correct programming.

If she is getting CT/XRT (chemo therapy/standard radiation) then the information is this link is very thorough:

http://www.jco.org/cgi/content/full/17/3/1020

It was done in 1999, 7 years ago and a lot has changed since then, but then much remains the same. It is also a study of CT/XRT only, without surgery.

You remember that we all respond differently to treatment.

When you can get a PET scan is up to your health care provider. I got mine within 2 days of the order, but I have an HMO.

They should also do a baseline TSH test and a hearing test if she is getting Cisplatin.

I didn't do flouride every day - 2-5 times a week. I am sure you will get many different answers on that depending on what people were using.