Patients are given an antibiotic for 2 days before the brachytherapy and on the morning of the procedure. Before the test, they have a small enema and are given medicines through the vein and into the spine for relaxation and to decrease any discomfort. (The test is done under general anesthesia for patients who require it.) The patient is moved on a stretcher into the MRI scanner and a catheter is inserted into the bladder through the penis. The bladder is filled with water and a tube is placed in the rectum. With the help of a plastic guide placed against the skin, about 14 to 18 needles are then placed in the prostate. Some stitches are sewn to hold the needles and the guide in place, and the tube in the rectum is removed. The patient is the transferred from the MR scanner into the CT scanner, where the rectal tube is reinserted and the needles are adjusted. A cystoscopy is done to make sure the needles do not enter the bladder. When the needles are adjusted, the tube is removed from the rectum and the patient is moved to the radiation oncology clinic.