Brachytherapy Treatment for Gynecological Cancer
Brachytherapy refers to radiation therapy that involves placing radioactive material directly into or adjacent to the tumor, rather than through external beams. Today, brachytherapy is a standard technique in the treatment of a large number of malignancies and often used in combination with EBRT. Brachytherapy treatments use radioactive materials such as cesium-137, iridium-192, palladium-103, or iodine-125. Radioactive sources that deliver radiation at a high dose rate such as iridium-192 are referred to as HDR (high dose radiation therapy). Through the use of brachytherapy, the radioactive source can be placed next to or directly into the tumor. Because the energy of the radioactive source is low, a high energy is delivered to the tumor, with nearby normal surrounding tissues receiving very little dose. Brachytherapy can be administered using a multitude of techniques- all dependent on the tumor being treated.
Intracavitary brachytherapy for gynecological cancers uses an applicator to introduce radioactive sources into natural or surgical body cavities. Insertion of the radioactive source (iridium-192) into body cavities has been a viable component of radiation therapy for many years, and is considered and essential component of treatment in the management of gynecological cancers. There are many applicators designed and used for the treatment of gynecological tumors. These designs allow for custom intricate dose distributions to maximize the dose to the tumor while also sparing the dose to adjacent, sensitive structures. The applicators used for gynecological treatments are of different lengths and diameters, all with the purpose of optimizing treatment delivery. Similar to prostate and breast brachytherapy, the procedure is done in a dedicated suite, usually consisting of 5-10 minutes of treatment. It involves placing an applicator into the vagina, either up the vaginal apex or through the cervical os and into the uterus. The prescribed treatment varies widely contingent on the type of cancer being treated. Treatments are most commonly given in 3-6 separate outpatient visits. During these visits a vaginal cylinder is gently placed in the vagina by a physician and stabilized with a base plate. A CT scan is done of the pelvis to confirm that the applicator is in the desired location. Once this is confirmed then the end of the applicator is connected via a transfer tube to a device that houses the radioactive material. This radiation source (Iridium-192) is pushed into the top of the cylinder and delivers a radiation treatment over about 5-10 minutes. The source is then retracted back into its housing unit, the vaginal applicator is removed, and the treatment is completed.