American Shared Hospital Services, together with its subsidiaries, leases radiosurgery and radiation therapy equipment to health care providers in the United States and internationally. It offers radiosurgery equipment for the Gamma Knife stereotactic radiosurgery, a non-invasive procedure for the treatment of malignant and benign brain tumors, and arteriovenous malformations, as well as functional disorders, such as trigeminal neuralgia. The company also provides image guided radiation therapy systems and related equipment that integrate imaging and detection components into an accelerator, which enables clinicians to plan treatment, verify positioning, and deliver treatment. In addition, it offers financing services for Elekta Gamma Knife units. Further, the company provides proton beam therapy services in Long Beach, California, as well as planning, installation, reimbursement, and marketing support services to its customers. Additionally, it is developing a medical device for the treatment of cancer patients using proton beam radiation therapy. As of March 1, 2015, the company operated 18 Gamma Knife units. It serves 18 medical centers in 17 states of the United States; and 2 medical centers in Turkey. American Shared Hospital Services was founded in 1980 and is based in San Francisco, California.