VortigERN: Variation of radiotherapy target volume definition, dose to organs at risk (OAR), and clinical target volumes using anatomic (CT) versus combined anatomic and molecular imaging (PET-CT): Intensity-modulated radiotherapy delivered using a tomotherapy hi art machine.

Abstract

TPS267 Background: Intensity-modulated radiotherapy (IMRT) has become the standard of care for radical radiotherapy treatment of head and neck squamous cell carcinomas (SCC). Whle benefits of IMRT include improving long-term xerostomia, accurate target localization is necessary to prevent geographical miss while sparing organs at risk (OAR). Although standard radiotherapy treatment planning (RTP) is performed using contrast enhanced CT scans (CE-CT), molecular imaging using 18FDG PET-CT scans are increasingly being explored to improve tumor localization. Recurrence following IMRT usually occurs within the high-dose area with early data raising the possibility of increased cure rates with dose escalation. Vortigern addresses the issue of optimal imaging for RTP volume definition and explores dose escalation in oropharyngeal SCC. Methods: Patients with oropharyngeal SCC suitable for radical radiotherapy are consented to take part in the study, 14 out of the planned 30 have been recruited. A PET-CT scan is a...