The needles pass through the space in front of the rectum and just behind the scrotum. The position of the needles is monitored during surgery with the ultrasound machine as well as a fluoroscopic Xray machine. The seeds are deposited after ensuring the proper location of the needles in the gland. This takes about 1 to 2 hours. The seeds may be placed individually with a spacing gun or the seeds may be implanted as ribbons or strands of seeds connected together (see here.)