For treating cervical cancer, often a combination of external and internal radiation therapy is utilized. For internal radiation special brachytherapy applicators called Tandem and Ovoid are used. Tandem is an applicator which is inserted through the cervical os into the uterus. Ovoids are a pair of applicators which are placed in the vaginal fornices, one on each side of the cervix. Using either Low Dose Rate or High Dose Rate brachytherapy systems, radioactive sources would be inserted into these applicators. These radioactive sources would deliver high doses of radiation to the tumor at the cervix with relatively small doses to the other organs in the pelvis. Internal radiation is a crucial part of curative treatment of cervical cancer.