How many rads?

I wonder if anyone knows how they work out how many rads to give. I have heard that radiotherapy after surgery is the most effective part of treatment.

I had a mastectomy, 4 FEC/TAX and then 12 rads plus Herceptin and Arimidex. I was originally told I was having 15 rads and then it changed to 12. I know of others who have had 30 rads having a mastectomy. I know that you have have less rads with a mastectomy but I just wondered why some get 12, some 20 some 30.

I don’t know but I have just finished 15 rads after my full mastectomy and when I saw my surgeon the other day he said he didn’t know why they had sent me for radiotherapy ,which is strange as he sent me to see the oncologist in the first place.I think we are all guinea pigs and they don’t know what the bleep they are doing.But ho hum if it helps , we go along with it coz what else can we do?..