Quality assurance of dysphagia-optimised intensity modulated radiotherapy treatment planning for head and neck cancer.

Justine Tyler,Catharine H Clark,Elizabeth Miles,Imran Petkar,Chris Nutting,Keith Rooney,Emma Hall,David Bernstein,Matthew Seithel

doi:10.1016/j.phro.2021.10.003

Abstract

This study aimed to assess the impact of the margin applied to the clinical target volume, to create the planning target volume, on plan quality of a novel dysphagia-optimised intensity modulated radiotherapy technique developed within a head and neck cancer multicentre randomised controlled trial. Protocol compliant plans were used for a single benchmark planning case. Larger margins were associated with higher doses to adjacent organs at risk, particularly the inferior pharyngeal constrictor muscle, but coincided with some improved low dose target coverage. A 3mm margin is recommended for this technique if local practices allow.

Highlights

Swallowing difficulty is a significant side effect for people who have been treated with radiation for head and neck cancer (HNC) [1,2]
This study aimed to assess the impact of the margin applied to the clinical target volume to create the planning target volume (CTV-PTV margin) on Dysphagia-optimised intensity modulated radiotherapy (DO-IMRT) plan quality of protocol compliant plans within an randomised controlled trial (RCT)
Larger CTV-PTV margins were associated with higher doses to some organs at risk (OAR), as expected for PlanIPCM and the ipsilateral parotid due to the greater PTV overlap and their constraints not being mandatory

Summary

Introduction

Swallowing difficulty is a significant side effect for people who have been treated with radiation for head and neck cancer (HNC) [1,2]. Dysphagia-optimised intensity modulated radiotherapy (DO-IMRT) has been shown to reduce dysphagia within a multicentre randomised controlled trial (RCT) by reducing dose to pharyngeal constrictor mus cles (PCM) [3,4,5,6]. Poor protocol compliance negatively impacts on clinical trial out comes, compliance can be improved by radiotherapy trial quality assurance (RTQA) [7,8,9,10,11,12,13,14]. RTQA is important in HNC RCTs where radiotherapy complexity has increased over time. An assessment of DO-IMRT plan quality implemented at multiple centres in an RCT has not been previously reported. This study aimed to assess the impact of the margin applied to the clinical target volume to create the planning target volume (CTV-PTV margin) on DO-IMRT plan quality of protocol compliant plans within an RCT

Objectives

Methods

Results

Conclusion