So the role of radiation therapy in the management of malignant glioma usually rests initially on a six weeks course of radiation therapy, which we described as external beam conformal radiation therapy. In the past, in the 1970s, when it was initially noted that chemotherapy may have a benefit combined with radiation therapy, that radiation therapy, in those days, actually was whole-brain radiation therapy. Now we're able to focus on the area of where the tumor is and can deliver radiation therapy in a fairly what we call conformal area, meaning conforming to where the tumor is or had been. We typically will use a two centimeter margin delivering a majority of the radiation therapy to that area. After an individual has received radiation along with their conformal radiation therapy with temozolomide, they quite often will have some degree of recurrence and depending on the type of recurrence that the individual has had, they can receive stereotactic radio surgery, which is a very relatively high dose of radiation therapy that is delivered to a very, very small area. So if an individual has a recurrence of their malignant brain tumor in a pattern or a lesion, that's greater than three centimeters, usually radiosurgery is not delivered because it loses its a large conformal nature. Typically speaking, if an individual has external beam radiation therapy for six weeks, 10, 15 years earlier, they sometimes can receive six weeks of radiation therapy once again. Well this is typically not the rule and the exception.