External beam radiation
The radiation oncologist will position you on the treatment table and make sure that you cannot move during the treatment (Fig 1.). You will be given pads or cushions to make it as comfortable as possible for you to keep still. While radiation therapy is given, the radiation oncologist will leave the room and monitor you from outside, but you will be able to talk the whole time. Beams from one or more directions may be used.
The amount of time that each beam is focused on a certain point is calculated before treatment starts.
The standard course of external radiation therapy usually lasts around 8 weeks, 5 days a week. You receive one dose of radiation per day. The treatment takes about 20 minutes each day, and you do not have to be admitted to the hospital.
Before the start of a course of radiation therapy you may get a CT scan. This is done to map the area that will be radiated as well as the surrounding tissue that should not be treated. In recent years, image-guided radiation therapy has become more widely available. For this type of therapy the radiation oncologist locates the affected organ very precisely with the help of an x-ray or CT scan to make sure that the radiation dose is delivered to that organ.
In prostate cancer another form of radiation therapy is possible, also called brachytherapy. For this type of treatment, a source of radiation is inserted directly into the prostate (Fig. 2).