Skin thickness estimation for high precision optical head tracking during cranial radiation therapytextemdash a simulation study

Accurate patient localization is a critical task in cranial radiation therapy. A combination of patientimmobilization and tracking of optical markers has established as common practice to compensatefor and prevent patient motion. However, since external markers lack a strictly rigid link to the bonestructure, localization errors may occur. To increase patient comfort and to tackle this drawback,makerless optical surface tracking can be seen as an alternative approach. Nevertheless, the elasticdeformation of the skin surface remains a source of registration errors. In this initial study wesimulate the interaction between an incident laser beam and skin to identify features providingenough information to predict skin deformation and compensate for these errors.