SU-E-J-193: Application of Surface Mapping in Detecting Swallowing for XXXX .

@entity1 @entity135 @entity5
PURPOSE: Recent evidence is emerging that long term swallowing function may be improved after radiotherapy for @entity135 if doses are limited to certain swallowing structures. Immobilization of @entity1 with @entity135 is typically done with a mask. This mask, however, doesn't limit @entity1 swallowing. @entity1 voluntary or involuntary swallowing may introduce significant @entity5 motion, which can lead to suboptimal delivery. In this study, we have examined the feasibility of using surface mapping technology to detect @entity1 swallowing during treatment and evaluated its magnitude. METHODS: The C-RAD Catalyst system was used to detect the @entity1 surface map. A volunteer lying on the couch was used to simulate the @entity1 under treatment. A virtual marker was placed near the throat and was used to monitor the swallowing action. The target motion calculated by the Catalyst system through deformable registration was also collected. Two treatment isocenters, one placed close to the throat and the other placed posterior to the base-of-tongue, were used to check the sensitivity of surface mapping technique. RESULTS: When the @entity1 's throat is not in the shadow of the @entity1 's chest, the Catalyst system can clearly identify the swallowing motion. In our tests, the vertical motion of the skin can reach to about 5mm. The calculated target motion can reach up to 1 cm. The magnitude of this calculated target motion is more dramatic when the plan isocenter is closer to the skin surface, which suggests that the Catalyst motion tracking technique is more sensitive to the swallowing motion with a shallower isocenter. CONCLUSION: Surface mapping can clearly identify @entity1 swallowing during radiation treatment. This information can be used to evaluate the dosimetric impact of the involuntary swallowing. It may also be used to potentially gate head-_-neck radiation treatments. A prospective IRB approved study is currently enrolling @entity1 in our institution. Research was funded through an Elekta grant.
