There are 373 physicians per 100,000 residents in the Greater Philadelphia reagion. Within a 100-mile radius of Philadelphia is the nation's largest concentration of health care resources. The area is home to several medical schools, dental schools, nursing schools, pharmacy colleges, and schools offering advanced degrees in biological sciences. World-class health care facilities, such as Children's Hospital of Philadelphia (ranked number one in U.S. children's hospitals), Alfred I. Du Pont Hospital for Children, Wills Eye Hospital (the first and largest hospital devoted to eye care), the Deborah Heart and Lung Center (site of the first open-heart surgery), and Fox Chase Cancer Center. The University of Pennsylvania houses a Comprehensive Cancer Center, and the city is served by more than a dozen regional trauma centers. The growth of the biotechnology companies in the last two decades has gained the area the reputation as the nation's foremost pharmaceutical and technology center.