[sarah]

you need a second opinion. Get the opinion from a different hospital and the top guy you can get to, let them now it's urgent.
I've only had rads once so can't comment on the twice idea however I know that despite the fact they say only once, it has been done more in certain cases but I don't know any personal histories.
I hope you have some good support and are taking anti-anxiety drugs or something. It's hard to be calm at these times.
Where is the hospital you go to? Maybe you can find a cancer survivor to stay with during this time??? so you don't have to travel twice a day and then get a leave of absence from your school.
big hug and love
sarah