The Microprocessor-Based Control System for the Fermilab Cancer Therapy Facility

A Neutron Cancer Therapy Facility (CTF) has been installed near the Fermilab 200 MeV proton Linear Accelerator. Sixty-six MeV protons extracted from the Linac are transported to a beryllium target that produces neutrons for patient treatment. A 6800-based microcomputer system, interfaced to the Linac control system, has been used since 1975 to perform the data acquisition and control functions required to operate the facility from the Linac control console. Beginning in March of 1977, routine operation of the facilityfor patient treatment has been done from a local medical control room using a disk-based 6800 system operated from a CRT terminal. This system provides the medical technologist with a display of information and control of parameters necessary for patient treatment, including the accumulation and limits of dose delivered to the patient. A hard copy of treatment parameters is generated for the patient's record following the delivery of each fractional treatment. Because the controlroom microcomputer uses a disk operating system, alternate programs may be loaded from disk and the system used for detector calibration, radiobiology irradiations and even further software development. Details of these two microcomputer systems, the parameters and devices they control and monitor, and the operating experience gained in on-line patient treatment use is presented.