The Presbyterian-University Hospital, Pittsburgh. The gamma knife: brain surgery without an incision

In July of 1987 a 20-ton gamma heavily shielded in a concrete "hot cell" was rolled into the basement of Presbyterian-University Hospital in Pittsburgh. Installation of the unit-one of only five in the world-and the first of its kind in the United States-was the culmination of 4.5 years of planning. It started in 1982 when the gamma knife was approved for marketing by the Food and Drug Administration. But because radioactive sources are sealed within the unit, it also had to be approved by the Nuclear Regulatory Commission (NRC), a process that required extensive and multiple levels of review within the nuclear agency. Although the device itself finally received NRC approval in 1986, the NRC Transportation Division refused to grant permission to transport a cobalt-loaded unit. So physicists at the University of Pittsburgh devised plans for on-site loading amidst the busy hospital environment in Pittsburgh! First a hot cell consisting of 3,000 lb of solid concrete block was constructed around the unit. Then, using robotic micromanipulators, the unit was loaded with 201 sources of cobalt-60, approximately 30 Ci each. The almost-6,000 Ci of cobalt provided a dosage rate of 396 cGy/min to the focal point, and patient treatment began one month later in August. Third-party reimbursement has been obtained from most major health insurance policies, and the procedure is approved for payment by Blue Shield and Medicare of Pennsylvania.