Steven A. Leibel

Varian Medical Systems, Inc. engages in the manufacture of medical devices and software for treating cancer and other medical conditions. It operates through the Oncology Systems and Proton Solutions segments. The Oncology Systems segment designs, manufactures, sells, and services hardware and software products for treating cancer with conventional radiation therapy, and advanced treatments. The Proton Solutions segment delivers proton therapy, a form of external beam radiotherapy using proton beams for the treatment of cancer. The company was founded by William Hansen, Edward Ginzton, Russell Varian, and Sigurd Varian in 1948 and is headquartered in Palo Alto, CA.

Physician Oncology Services LP provides healthcare services. The company offers radiation oncology services in the United States. It was founded in 2006 and is headquartered in Atlanta, GA.