Hi Sandy, I had CK Dec. '10. I had the radiation for the 3 days. I had 18 gy of radiation. It is my understanding that with the 5 day fractionated radiation it is the same.... 18 gys of radiation. Its just a little less each day with the 5 day. I don't believe it makes any difference in the side effects. Initially, you will have very little side effects..maybe a little tired. But in the ensuing weeks you will notice perhaps some numbness, some wonkiness, head pain, balance might seem a bit off etc etc.. I had all of the above. A dose of a Medropak helped a little. I am 15 months post CK and this week I have experienced a little numbness on the AN side and some very slight balance issues. All in all I am doing AOK and will have another MD visit as well as an updated MRI in May. It's quite a journey but I wouldn't have it any other way. Best Regards, Joan