Around six of the coils, which are 1cm to 2cm long and cost 80-100 pounds each, are inserted in the prostate prior to treatment.
Gold is used because it shows up on scans and few people are allergic to it. Once fitted, the coils stay in the prostate for life.
Amit Bahl, lead doctor at the Bristol Haematology and Oncology Centre oncology, said that in radiotherapy on the prostate, radiographers try to minimise the target area for radiation.
However, since the prostate tends to move, especially over several weeks of regular treatment, it helps to scan patients before each dose.
"You cannot see the prostate when you are treating patients on the radiotherapy machines because it is soft tissue and all looks the same," the Daily Mail quoted Bahl as saying.
"You can see the bony structure of the hip but not the prostate.
"If you put the gold coils into the prostate you can see them in scans and make sure that any movement of the prostate is accounted for," he said.
Scans are taken of the pelvis after the coils have been implanted so that radiographers know where to direct the radiation and further scans are done before each treatment and compared to the originals to check where to deliver the radiotherapy.
Adjustments can then be made while the patient is on the couch to ensure the radiation goes to the right area.
"We did not know what we could not see before," Bahl said.
"And that makes you realise how important this is.
"It gives you the confidence that you can narrow down the beams to cover just the prostate without missing the target.
"Hopefully it will give patients better survival chances and a better quality of life.
"So far 14 men have had the gold coils inserted into their prostates prior to radiotherapy and the hospital is intending to use the precious metal on a further six patients," he added.