How to you account for motion when contouring head and neck primaries in more mobile areas such as base of tongue and larynx?

We instruct our patients not to swallow during the CT simulation. We do not account for organ motion when contouring. The duration of intrafraction swallowing during the entire course of conventional RT has been reported to be small, at 0.43% of the total irradiation time (1).

1. van Asselen B, Raaijmakers CP, Lagendijk JJ, et al. Intrafraction motions of the larynx during radiotherapy. Int J Radiat Oncol Biol Phys 2003;56:384–390.

For any target which tongue positioning is important, we utilize bite block placement to reduce variability. This also helps reduce margin overlap with oral mucosal sites that wouldn’t otherwise need coverage. No special accounting for motion with margins here.

Even when a pt is instructed not to swallow, the positioning of larynx can be variable day/day regardless of how well the more fixed structures are matched on IGRT. This became more evident to me after incorporating daily Cbct matching. ...