concord medical services holdings limited, through its subsidiaries, operates a network of radiotherapy and diagnostic imaging centers in the people's republic of china. the company operates in network and hospital segments. the company's services comprise linear accelerators external beam radiotherapy, gamma knife radiosurgery, head gamma knife systems, body gamma knife systems, and diagnostic imaging services. it also offers other treatments and diagnostic services comprising electroencephalography for the diagnosis of epilepsy; thermotherapy for pain relief after radiotherapy and chemotherapy; ultrasound therapy for the treatment of cancer; stereotactic radiofrequency ablation for the treatment of parkinson's disease; and refraction and tonometry for the diagnosis of ophthalmic conditions. in addition, the company provides clinical support services, including developing treatment protocols for doctors; and organizing joint diagnosis between doctors in its network and clinical resear