INTERSTITIAL BRACHYTHERAPY (IMPLANTING RADIOACTIVE SEEDS) FOR PROSTATE CANCER: BASIC APPROACHES
There are many variations, but the basic means of access is the transperineal approach, reaching the prostate through the perineum, the area between the scrotum and rectum. Before beginning interstitial brachytherapy, you should undergo an extensive physical examination and a cystoscopy to evaluate your particular anatomy and make sure the cancer is contained within the prostate. You should also have a CT scan, so your doctors can get a closer look at the prostate and plan the way the treatment will be administered.
One transperineal approach involves open surgery and begins much like the radical prostatectomy—with a Foley catheter, an abdominal incision and a staging lymph node dissection (see Chapter 3) to make sure the cancer has not spread to the pelvic lymph nodes. If the lymph nodes are cancer-free, the procedure continues. When doctors reach the prostate and can see the tumor, they draw an outiine by implanting tiny bits of material, which can be seen on an X-ray, around its edges—like dotted lines or stakes marking a boundary. Then the doctor inserts a long needle through the perineum into the prostate, far enough so that its tip sticks out of the bladder neck. This is called a stabilizing needle, and it becomes an axis that helps hold a template in place. The result is a highly sophisticated kind of “paint-by-numbers” map of the prostate that helps doctors know exactiy where to insert the other needles. The doctor’s finger, inserted in the patient’s rectum, helps guide placement and depth of the needles. With this approach, it’s also possible for doctors to place seeds in the seminal vesicles (however, this may cause severe rectal complications.
Now, instead of simply inserting the radioactive seeds, the doctors send the patient out of the operating room and to the hospital’s radiation oncology department. “Dummy” (not radioactive) seeds are implanted, and then photographed by an X-ray machine. These fake seeds make possible ultra-precise, three-dimensional placement of each of the real radioactive seeds, which are implanted next. Also, the amount of radioactive material can be fine-tuned from seed to seed to ensure an even distribution of radiation. Now comes a little help from outside—external-beam radiation therapy. The radiation zeroes in on the implants and turns them into little antennae, which help focus and amplify the radiation. The seeds are removed—which should minimize the risk of infection—and a course of external-beam radiation therapy will begin two to four weeks later.
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