Facility design, environmental protection, and planning method for Cf-252 therapy at the Cancer Institute Hospital, Tokyo

A shielded facility for storage and handling of up to 100 μg of Cf-252 seed assemblies, afterloading cells and tubes, and a remote afterloader using four tubes totaling 60 μg were designed and constructed. The radiation protection survey of the completed facility was performed, and applicability of the guide by Stoddard and Hootman (Cf-252 Shielding Guide, USAEC Report DP-1246, 1971) for spherical shields was confirmed by the present design calculation and survey. For local shielding such as bedside shielding, however, the guide cannot be applied because scattered neutrons from the floor, ceiling, and wall may reach behind the shield. This paper also describes the treatment planning method for Cf-252 implants with the aid of a computer. (Auth.)