After a few hours, when the radiation dose has been calculated, a radioactive substance called iridium is administered. The needles placed in the prostate are connected to a radiation machine, and thin wires with radioactive material on the tips are inserted into each needle and withdrawn a little at a time. The process takes about 20 to 30 minutes. The patient is then disconnected from the machine and undergoes another MRI scan to confirm the position of the needles. The needles and catheter are then removed and the patient is monitored for a while before going home. Patients then have 5 weeks of external beam therapy, followed by a second brachytherapy treatment.