Radiation therapy is one of the more commonly used methods for the treatment of localized prostate cancer. It involves the use of ionizing radiation to kill the cancer cells.
Intensity-Modulated Radiation Therapy (IMRT) is a radiation technique that focuses very small beams of radiation at a targeted tumor from many different angles. This type of technology allows for a very direct treatment of the tumor. By using a collimator, a device that adjusts the shape and size of the beam, the beam is able to be carefully focused and shaped to the target and minimizes radiation to surrounding organs that are not involved in the cancerous process. Thousands of very thin beams are focused on the prostate, rather than one large beam that may be used in standard external beam radiation therapy or three-dimensional conformal radiation therapy (3D-CRT). 3D-CRT relies on a three-dimensional image to determine the treatment plan and reduces the radiation dosage compared to standard therapy, however the treatment is not as directed as that of IMRT.
Brachytherapy refers to the implantation of a radioactive source into the prostate. The most common types of seeds implanted are permanent seeds that consist of the radioactive isotopes of either Iodine-125 (I 125) or Palladium-103 (Pd 103). I -125 has a half -life of 60 days and Pd 103, 17 days. These seeds - small pellets approximately the size of a grain of rice - are placed in a minimally invasive operative procedure. The seeds are placed in the perineum (the area between the rectum and the scrotum) with the aid of a transrectal sonogram that helps direct their placement. Although they are permanently implanted the seeds lose most of their radiation dosage within the first six months that they are implanted.
High dose brachytherapy is also offered at some centers. In this non-surgical procedure, thin catheters containing radioactive sources are inserted into the prostate. A treatment protocol will determine how long the radioactive source stays within the prostate and how many applications are required. After treatment, the catheters are removed.
Patients who are diagnosed with localized prostate cancer have many different options available for treatment. Consultation with your Urologist and a radiation therapy will help determine the best radiation therapy technique for you.