Field Plan for Radiation Therapy

Last Modified: January 2, 2008

Dear OncoLink "Ask The Experts,"

I am undergoing 3dcrt for psa recurrence post prostatectomy. At the start of my treatment, I attended a presentation by a radiation oncologist who used 3dcrt with four dosage planes in the first part of the radiation treatment, but toward the end of the of the treatment period he switched to six dosage planes. I assumed that this was standard, but my radiation oncologist plans to continue the four plane dosage for my entire treatment. When I asked her about six dosage planes, she answered that she never uses six planes in cases such as mine and sees no benefit in it. Why would this other doctor, who sounded very knowledgeable, advocate six planes to complete the treatment?

Richard Whittington, MD, Associate Professor of Radiation Oncology at the University of Pennsylvania School of Medicine, responds:

I think that what you are saying is that you were advised to receive post-prostatectomy radiation after prostatectomy for a biochemical recurrence of his tumor. The initial physician recommended a 4 field plan for the first phase and a 6 field plan for the second phase. This is one of those issues that you learn a system and its strengths and weaknesses and you use it until you find a better system and learn its strengths and weaknesses. Both treatment plans are acceptable and are used by many outstanding clinicians.

In this situation I use a 4 field technique all the way because I believe the rectal dose is lower with that plan and the volume of rectum treated is smaller. Some people worry that the dose to the hip is higher, but I believe it is still less than 40Gy and I have not seen many instances of hip problems with this technique. I can recall only 6 patients right off the top of my head that required hip replacement, and I have treated about 9,000 men with prostate cancer since I came to Penn.

Bottom Line-The Cowboys are a very good football team, and the Colts are a very good football team. If the Cowboys used the Colts play book, they would not be as good. The same can be said for the Colts using the Cowboys play book.