Brachytherapy is the treatment of disease, usually cancer, at a short distance with a radioactive isotope placed on, in, or near the tumor. This allows the tumor to receive a high dose while keeping the dose low to the surrounding tissues. Brachytherapy has been in use for over a hundred years and has been used to cure cancer for ninety years. It can be used alone or in combination with external beam irradiation.
At Lexington Medical Center the most frequently used types of internal radiation are high dose-rate brachytherapy, interstitial, and intravenous brachytherapy. Most of these procedures require IV sedation, but interstitial treatments are
sometimes done under general anesthesia.
In high dose-rate brachytherapy, a radioactive pellet of iridium is positioned at the tumor site, and the tumor is then treated under computer control. The radioactive pellet is guided to the tumor, treats it, and is then withdrawn back into its safe. This type of treatment is useful in many different types of tumors and can be applied with many different types of applicators. For instance, placing a hollow plastic catheter in the tumor can treat lung cancers. This placement is done through a bronchoscope. The cancer is then treated through the plastic tube, under computer control.
This same type of treatment can be used to treat cervical cancer by placing metal applicators at the tumor and then having the radioactive pellet treat at designated locations inside the metal applications. Because the radioactive pellet is less than 1 by 3 mm in size, it can be placed in an almost unlimited number of sites in the body. Because the dose is delivered very rapidly, hospital stays are not required, and the treatment is delivered as an outpatient over several sessions.
Interstitial brachytherapy involves the placement of permanent or temporary radioactive seeds in the tumor with plastic or metal needles. Permanent seeds have a short half-life and therefore their activity is limited to several months. Temporary source treatments utilize the high does rate Iridium 192 which treats the tumor in minutes. Tumors may be successfully treated with either technique. Prostate cancer, for instance, is treated with Palladium or Iridium alone or in combination with IMRT. Depending on the isotope used, this may be either an inpatient or outpatient procedure.
Intravenous brachytherapy involves the administration of liquid radioactive molecules or compounds by injection into a vein. These isotopes preferentially seek tumor sites and then irradiate them. An example of such treatment is the use of strontium or samarium to treat bony metastatic disease. The radioactive material is injected by the Radiation Oncologist and then treats the tumor via the bloodstream. These radioactive isotopes are of low energy; so the patient can leave the hospital immediately after the procedure, even though they are mildly radioactive. This radioactivity declines over subsequent months. The Radiation Oncologist is trained to administer many different types of brachytherapy, not all of which are mentioned here. You will be given specific facts concerning the procedure, which is being offered to you, as well as specific instruction about self-care.
The newest
type of IV brachytherapy involves attaching a radioactive
isotope to an antibody against the tumor. This type of treatment
is now available of lymphoma (Zevalin and Bexxar), and will soon
be released for other tumors.
The Radiation Oncologist is the expert in administration of this type of treatment and has a specific license from the State of South Carolina to administer these materials, as regulated by the Nuclear Regulatory Commission.
ARE THERE ANY SIDE EFFECTS?
You are not likely to have severe pain or feel ill during brachytherapy. If there is an applicator holding your implant, it may be somewhat uncomfortable. The Radiation Oncologist can order medicine to relax you or to relieve pain if you need it. Some patients feel weakened after having anesthesia, but this does not last long.
Your Radiation Oncologist will advise you if there is any need to restrict your activities after you are discharged. Most patients are allowed to do as much as they feel like doing. You may need extra sleep or rest breaks in your first days at home, but you will regain strength quickly.
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