Here is a link to a study that was done ( 14,168 patients ) comparing the results of 11,330 patients that received traditional radiation treatment of the prostate to 2,838 patients who received hypofractionization treatments ( such as CyberKnife & RapidArc).
http://www.ncbi.nlm.nih.gov/pubmed/22966812
Study Conclusion :
" These results indicate that the high fractionation sensitivity is an intrinsic property of prostate carcinomas and they support the use of hypofractionation to increase the therapeutic gain for these tumours. "
Tradition treatment is called hyperfractionization or conventional fractionation - many treatments ( 35-40 over 5-6 weeks ) , each of a lower dose. Usually the total dose is about 80 Gy.
Hypofractionalization delivery is a low number of doses, but each dose is much greater than compared to conventional fractionation, ( 4 or 5 doses, everyday or every other day). Usually the total dose is about 37 Gy. But because of the low alpha/beta ratio of CaP, the BED ( biological equivalent dose ) is about the same as conventional fractionation - 80 Gy.
There is some reverse engineering to all of this - the alpha/beta ratio of CaP can't be measured directly. It had been determined at first by the results of HDR Brachytherapy. It's my understanding that's how it was theorized that external beam hypofractionization would also give good results. But that wasn't possible until a more accurate delivery system was devised so toxicity to good tissue didn't result, such as CyberKnife and RapidArc.
CyberKnife has been FDA approved since 2002 and the first prostate patient was treated the same year. I believe I read he was a medical doctor - neurosurgeon or anesthesiologist, I think.
Here is a link that delves more into alpha/beta ratio and the effect on BED. Don't ask me to completely explain this stuff :
http://www.eyephysics.com/tdf/models.htm