Adaptive Replanning Strategies Accounting for Shrinkage in Head and Neck IMRT

Shrinkage does not result in significant dosimetric difference in targets and critical structures, except for the parotid gland, for which the mean dose increases by ∼10%. The benefit of replanning is improved sparing of the parotid. The combination of replanning and reduced margins can provide up to a 30% difference in parotid dose.