Also known as internal radiation therapy, brachytherapy delivers radiation directly into the tumor (called interstitial brachytherapy) or into a surgical cavity or body cavity near it (called intracavitary brachytherapy). By delivering the radiation directly into the tumor or into a nearby cavity, the radiation only needs to travel a short distance, causing less damage to the surrounding normal tissue. Radioactive material is sealed in a delivery device called an “implant.” The implant is inserted into the body using an applicator (often a hollow tube called a catheter). Imaging tests, such as x-rays, CT scans, or MRI scans, are used to guide the radiation oncologist in placing the implant. Depending on the location of the tumor or cavity, the patient will receive either general anesthesia (drugs used to put the patient into a deep sleep) or local anesthesia (drugs used to numb the area being treated). Implants can be permanent or temporary. For high-dose-rate (HDR) treatment, the radiation oncologist places high-dose implants into the tumor or cavity for a short period of time (generally less than one hour) and then removes them. HDR treatment is given on an outpatient basis and may be repeated over several days or several weeks. Currently, HDR treatment is offered to patients with gynecologic cancers, such as cervical cancer, endometrial (uterine) cancer, uterine sarcoma (cancer of the muscle and supporting tissues of the uterus), and vaginal cancer.