Quality Improvement Review of Radiation Therapy Treatment Planning in the Presence of Dental Implants

Abstract

A common problem that arises in radiation therapy treatment planning for head and neck cancers is the streaking artifacts in CT images produced from metallic dental implants (MDIs). These artifacts cause the densities of MDIs and surrounding tissues to appear incorrect on the CT scan, which leads to inaccurate dose calculations for these areas. The purpose of this study is to quantify and compare the effect of metallic dental implants (MDI) on dose distributions calculated with a Collapsed Cone Convolution Superposition (CCCS) algorithm (Pinnacle3) with a Monte Carlo algorithm (Monaco), with and without correcting for the density of the MDIs. The Monte Carlo dose calculation indicated that PTVs coverage was lower than the Uncorrected Pinnacle3 plan had calculated. In some cases, the Monte Carlo algorithm indicated that surrounding regions of interest (ROIs) received a significantly higher dose. Not properly accounting for dental implants can impact both the high dose regions and the low dose regions. This study implies that if MDIs and the artifacts are not appropriately contoured and given the correct density, there is potential significant impact on Planning Target Volume (PTV) coverage and doses to surrounding organs at risk.