Varian Medical Systems, Inc. designs, manufactures, sells, and services medical devices and software products for treating cancer and other medical conditions worldwide. It operates through Oncology Systems and Proton Solutions segments. The Oncology Systems segment offers hardware and software products for treating cancer with radiotherapy, fixed field intensity-modulated radiation therapy, image-guided radiation therapy, volumetric modulated arc therapy, stereotactic radiosurgery, stereotactic body radiotherapy, artificial intelligence based adaptive radiotherapy, and brachytherapy, as well as quality assurance equipment. Its products include linear accelerators, brachytherapy afterloaders, treatment accessories, and quality assurance software; and information management, treatment planning, image processing, clinical knowledge exchange, patient care management, decision-making support, and practice management software. This segment serves university research and community hospitals, private and governmental institutions, healthcare agencies, physicians' offices, medical oncology practices, radiotherapy centers, and cancer care clinics. The Proton Solutions segment designs, develops, manufactures, sells, and services products and systems for delivering proton therapy for the treatment of cancer. The company has a strategic agreement with McKesson Corp. to supply treatment delivery systems and planning, services, and radiotherapy information system solutions to its U.S. Oncology Network and Vantage Oncology affiliated sites of care; and a strategic partnership with Siemens AG to represent Siemens diagnostic imaging products to radiation oncology clinics in the United States and other select markets. Varian Medical Systems, Inc. was formerly known as Varian Associates, Inc. and changed its name to Varian Medical Systems, Inc. in April 1999. The company was founded in 1948 and is headquartered in Palo Alto, California.