MRI-Guided Soft Tissue Alignment for Head-and-Neck Radiotherapy and Margin Adaption Assessed by a GPU-Based Dose Deformable Regsitration Framework

Introduction

Bony landmark based registration using daily cone beam CT image is a widely adopted but compromised alignment procedure used for head-and-neck (H&N) radiotherapy (RT). MR image provides a superior soft tissue contrast, which allows excellent IGRT alignment on soft tissues such as target or critical structures nearby. The purposes of this work are 1) to analyze the inter-fraction patient setup using soft-tissue target and design an appropriate clinical target volume (CTV)-to-planned target volume (PTV) margin for H&N MRI-guided IGRT; and 2) to assess the resulting dosimetric consequences when margin adaption is performed based on weekly MR images via an in-house GPU-based dose deformable registration framework.