One of the standard methods is to permanently implant small markers (gold spheres or cylinders) in the prostate and use x-rays in the radiation therapy treatment room to determine whether the markers are in the correct position. If the markers are in the correct position, then the assumption is that the prostate also is in the correct position. If the markers are not in the correct position on the x-ray, then the table that the patient lies on can be shifted so that the markers are in the right place.