On designing room shielding for total-body irradiation.

When designing shielding for total-body irradiation as an additional modality of treatment in an ordinary radiation therapy room, the extended treatment distance used for these patients greatly increases the workload because of the inverse-square factor. In a seeming contradiction to logic, for a facility with an exterior wall in the path of one lateral primary beam, and a restricted area behind the other primary wall, the overall shielding requirements are lower if the TBI patients are treated with the machine oriented toward the occupied interior.