The two type of radiation are:
- Brachytherapy - the permanent implantation of radioactive "seeds" (small pellets of iodine or palladium isotopes) directly into the prostate. These seeds emit a constant dose of radiation to the surrounding tissue, killing the cancer cells. After about a month, the emission is significantly reduced to negligible amounts. Brachytherapy is more often an option for smaller size prostate glands and earlier stage prostate cancers.
- External beam radiation - the exposure of cancerous cells to x-rays from external sources. In this treatment, the patient is exposed to short exposures to high-energy x-rays each day over a period of several weeks. The Trilogy™ system precisely controls radiation beams so that only the tumor site receives the full radiation, significantly reducing the exposure of normal cells.
Radiation treatments may be combined with hormone therapy to minimize tumor growth if treatments cannot begin immediately, to reduce the size of an enlarged prostate, or to provide additional theraputic benefit for higher-risk patients.
Brachytherapy is the implantation of 40-150 small pellets of a radioactive substance into the prostate. This procedure is done in a single day under general anesthesia, takes about three hours to complete, and does not require an overnight stay in the hospital.
During the procedure the seeds are implanted uniformly throughout the prostate. The seeds are made up of iodine or palladium and release small amounts of radioactivity into the surrounding prostate that kill the cancer cells. The seeds are permanently placed, and like all radioactive material, the emissions decline over time and after a few weeks they are no longer active. Some precautions should be taken to limit prolonged close contact (closer than three feet) with children or pregnant women for the first month after the implantation, but after that there are no problems.
About a month after the implantation, patients return for a CAT scan that allows the seed and dosage distribution to be documented. About three months after that, the patient returns again for a follow up exam that includes a PSA test.
Side effects of brachytherapy may include difficulty urinating, urinary urgency or burning, and perhaps loose stools. Side effects generally decline after a month.
External beam radiation
This treatment is much like getting a regular x-ray, but for a longer time. Each treatment lasts only a few minutes. Men usually have 5 treatments per week in an outpatient center over a period of about nine weeks. The treatment itself is painless.
The process begins about three weeks before the fisrt radiation treatment session with the implantation of two gold coils into the prostate. These coils allow the precise calibration of the radiation beam during the subsequent treatment sessions. The procedure takes about 30 minutes and is performed under local anesthesia. Patients only need someone to drive them home if they receive additional sedation.
Two weeks before the treatment sessions begin, the patient comes to the hospital for a one hour planning session where they have a CAT scan and an MRI and get their treatment schedule finalized.
When the treatment sessions begin, the patient comes to the hospital every weekday for about nine weeks. Each day includes a 30 minute visit where they receive a radiation treatment, and once a week they meet with their doctor and other team members to report on progress and any side effects.
Norris Cotton Cancer Center treats patients with prostate cancer with the Trilogy™ System from Varian Medical Systems. Trilogy combines specialized medical imaging with precise and powerful radiation delivery, to enable advanced new therapies that shorten treatment times, reduce side effects, and offer new hope for patients previously considered to be untreatable.
Norris Cotton Cancer Center is the only center in northern New England with a Trilogy system. This allows us to provide stereotactic (three-dimensional) image-guided radiotherapy and radiosurgery. Trilogy provides the latest in high dose, precision radiation therapy, can be fine-tuned to a focal point of a one-millimeter diameter sphere, and includes high definition X-ray and CT (computed tomography) imaging, and automated patient positioning. Together, these features enable precise tracking of a tumor to ensure that each high-powered beam is delivered to the right point, at the right time.
Side effects of radiation therapy can include diarrhea, rectal leakage, irritated intestines, and impotence (erectile dysfunction).
After the completion of the treatment sessions, there is a series of follow up visits starting one month after therapy ends and continuing every three - six months as long as the physician specifies.