Estimation of shielding factors for linear accelerators.

There have been a number of persons who have estimated that the use of multi-leaf collimation and IMRT techniques increase the workload in treatment rooms to the extent that assumptions used in shielding calculations should reflect these increased workloads. This paper examines the workloads in a large department with treatment machines of varying energies and techniques. While the sample size examined is limited, the data presented demonstrate that the standard assumptions may still be sufficiently conservative that no substantive changes may be needed.