Relocation of the helium ion radiotherapy program from the 184" Synchrocyclotron to the Bevalac

The closure and dismantling of the 184" Synchrocyclotron has required that the helium ion radiotherapy program be transferred to the Bevalac. To this end, the extremely precise and sophisticated patient positioner ISAH (Irradiation Stereotactic Apparatus for Humans) has been relocated to a new radiation enclosure at the Bevalac. This has formed the basis for a new fully equipped patient treatment area which is now totally integrated into the existing biomedical facility at the Bevalac. Now fully commissioned, this new area has seen the resumption of the very promising ocular melanoma, AVM, and precision dose-localization treatment programs after only a six-month interruption. Details of the move of ISAH and its modifications to fit into its new environment are presented, along with the instrumentation and changes to the Vax-based control system that were needed to integrate the new treatment room into the existing biomedical facility. Operation of the full facility is discussed, with emphasis on the substantial increase in complexity of scheduling and resource allocation