Currently four types of treatment are used: Surgery, Radiotherapy (RT), Chemotherapy (QT) and Immunotherapy (IT). Surgery is the most common treatment for intracranial tumors. RT is the use of X-rays or gamma and its purpose is to eliminate tumor cells from the outside and reduce their size (external beam RT); RT can also be used by placing radioactive materials into the tumor, through thin plastic tubes, radioisotopes, in order to remove the tumor cells from the inside (internal RT). QT uses drugs to kill tumor cells. It can be administered orally, parenterally or intrathecally; QT is considered a systemic treatment.