Poster — Thur Eve — 41: Determination of Realistic Workload and Use Factors Using the Varian ARIA Database

Abstract

Shielding design calculations used in megavoltage radiation therapy essentially reduce to determination of barrier thicknesses. A shielding barrier serves to attenuate the radiation dose from a high level produced inside a therapy room to a lower “design goal” level at a point‐of‐interest outside. The calculation must account for both radiation physics (barrier attenuation) and for the various clinic‐specific parameters that serve to modulate the design goal and the dose that impinges on the barrier. While the physical data relating to attenuation of megavoltage beams in concrete and other barrier materials is readily available (eg in NCRP Report 151 or via the NIST website), clinic‐specific parameters must be determined by the clinical physicist. Such parameters include the workload W of the treatment machine, the use factor U of the barrier in question and the occupancy T at the point‐of‐interest. In this submission we show how data archived in a clinic's record‐and‐verify system can be used to compile realistic workload and use factors.