A treatment is planned using a single field at a distance of…

A treatment is planned using a single field at a distance of 100 cm and a 6 MV beam (Dmax=1.5 cm). In order to accommodate the target volume, the distance must be extended to 110 cm. The depth of the target is 3 cm. If the original PDD value at depth was 91.4%, what is the PDD value at a distance of 110?