These are also known as fiducial markers, and are used to help target the radiation at the prostate gland better. They are tiny, smaller than a grain of rice. They are made of pure gold, so the body does not react with them.
Three seeds are injected into the prostate gland by your urologist or sometimes by another physician. The procedure is very similar to a biopsy: you need to do a bowel cleanse with an enema or magnesium citrate beforehand. You need to take preventative antibiotics for a few days, usually starting on the evening before the procedure. You may be given a sedative at the time of the procedure. An intrarectal ultrasound is used to help guide the insertion of the needle. One advantage of this compared with the biopsy is that there are only 3 needle pokes instead of 12!
The 3 seeds form the corners of a triangle inside the prostate. When the radiation therapist sets you up for treatment each day, they do a scan which shows the marker seed triangle, and they can finely adjust the treatment table position so that the three seeds line up perfectly with where they are supposed to be . This helps the treatment machine “lock in” on your prostate gland. Think of it as GPS for your prostate.
The seeds do *not* correlate with where the cancer is in the prostate gland. They simply help with focusing on the entire prostate gland. The seeds are not radioactive, and this is not the same thing as a “seed implant”. These markers are permanent and they are not removed when the treatment is over. They rarely cause complications. Like a biopsy, sometimes an infection or bleeding can occur following the procedure.
Some people cannot have marker seeds placed for various reasons such as being on blood thinners. The seeds are not mandatory, but they do increase the precision of the radiation. If the seed markers are not available, then the therapist will use the outline of the prostate, rectum, and bladder to get you lined up into the proper position each day. We do not usually use marker seeds on men that have had their prostate removed because there is not much tissue left to inject them into.
Q) Do the marker seeds help concentrate the radiation into the cancer?
A) No. The marker seeds do not concentrate the radiation and they do not show where the cancer is.
Q) Do you take the marker seeds out after radiation is finished?
A) No, that would be difficult and dangerous. They stay in the prostate permanently and they do not react with the body.