Additional Study Information: Optune is a portable, battery-operated device that generates TTFields at a specific frequency. The TTFields are delivered to the brain through 4 sticky bandages (which hold ceramic discs) that are placed on the surface of the head (called arrays). The arrays create electric forces within the brain that disrupt cancer cell division. Optunes TTFields are a novel type of cancer treatment that have been shown in laboratory studies to slow the growth of tumors, without causing significant side effects. In addition, the use of TTFields as a cancer treatment has been tested in numerous studies of participants with GBM brain cancer. Based on the results of these studies, Optune is approved for the treatment of GBM in many countries, including the United States. The purpose of the current research study is to test if the addition of Optune at the time will improve clinical outcomes compared to the approved use of Optune. It is planned that 950 subjects with a new diagnosis of GBM and who are planned to have radiation therapy with temozolomide, will participate in this study after surgery or biopsy.