Unlike other radiation modalities such as IMRT, IGRT and proton beam, prostate brachytherapy is immune to prostate motion.
There are many different technologies to treat prostate cancer with radiation, such as Intensity-Modulated Radiation Therapy (IMRT), Image-Guided Radiation Therapy (IGRT), and proton beam therapy. These are all technologies that have been developed to promote and deliver the concept of dose escalation to the prostate; which means the more radiation you give to the prostate, the more likely you are to cure the cancer. However, there are adjacent structures to the prostate, which include the bladder and the rectum, and ideally, these structures should not receive any radiation. Thus, this limits the amount of radiation that can be delivered safely from the actual source. People have gone to great effort in order to account for prostate motion during treatment using external beam radiation sources, which they call “intrafractional motion”. During the treatment time the prostate is moving and I’ve heard of gimmicks, such as the Calypso technology, where they actually “track” the beam, which is really misleading. This is not any different from any other form of image-guided radiation therapy. I have a real problem with that. I also think that people look at the concept of proton beam, which is a very sophisticated treatment; however, it has not proven itself to be superior to conventional x-ray therapy. In fact none of those technologies have proven superiority over one another and none have proven superiority to brachytherapy. Brachytherapy is immune to this concept of prostate motion because the actual source of radiation lies within the prostate and the dose at the edge of the prostate is a constant. It’s just simply a science; it’s an actual science, radiation physics. And so brachytherapy takes advantage of that. These discussions of prostate motion don’t even apply to prostate brachytherapy. For that reason alone, it clearly is the best treatment, with its ability to confine dose to the prostate and avoid bladder and rectum.