Multi-institutional comparison of volumetric modulated arc therapy vs. intensity-modulated radiation therapy for head-and-neck cancer: a planning study

Andrea Holt,Mark P Arends,Danny Schuring,Erik W Korevaar,Rob Jw Louwe,Martina C Kunze-Busch,Corine Van Vliet-Vroegindeweij,Dirk Van Gestel

doi:10.1186/1748-717x-8-26

Abstract

BackgroundCompared to static beam Intensity-Modulated Radiation Therapy (IMRT), the main advantage of Volumetric Modulated Arc Therapy (VMAT) is a shortened delivery time, which leads to improved patient comfort and possibly smaller intra-fraction movements. This study aims at a treatment planner-independent comparison of radiotherapy treatment planning of IMRT and VMAT for head-and-neck cancer performed by several institutes and based on the same CT- and contouring data.MethodsFive institutes generated IMRT and VMAT plans for five oropharyngeal cancer patients using either Pinnacle3 or Oncentra Masterplan to be delivered on Elekta linear accelerators.ResultsComparison of VMAT and IMRT plans within the same patient and institute showed significantly better sparing for almost all OARs with VMAT. The average mean dose to the parotid glands and oral cavity was reduced from 27.2 Gy and 39.4 Gy for IMRT to 25.0 Gy and 36.7 Gy for VMAT, respectively. The dose conformity at 95% of the prescribed dose for PTVboost and PTVtotal was 1.45 and 1.62 for IMRT and 1.37 and 1.50 for VMAT, respectively. The average effective delivery time was reduced from 13:15 min for IMRT to 5:54 min for VMAT.ConclusionsIndependently of institution-specific optimization strategies, the quality of the VMAT plans including double arcs was superior to step-and-shoot IMRT plans including 5–9 beam ports, while the effective treatment delivery time was shortened by ~50% with VMAT.

Highlights

Compared to static beam Intensity-Modulated Radiation Therapy (IMRT), the main advantage of Volumetric Modulated Arc Therapy (VMAT) is a shortened delivery time, which leads to improved patient comfort and possibly smaller intra-fraction movements
Small differences were found between IMRT plans from different institutes, which may be due to each institute’s preferences and traditions in sparing the different organs at risk (OARs) in daily clinical practice
Regardless of patient and institute, with VMAT the isodose surfaces encompassed the planning target volume (PTV) tighter with similar or better sparing of the OARs. This was reflected in steeper dose fall-offs for the corresponding dose volume histogram (DVH) of the different PTVs and smaller dose conformity indices (CIs) for VMAT plans

Summary

Introduction

Compared to static beam Intensity-Modulated Radiation Therapy (IMRT), the main advantage of Volumetric Modulated Arc Therapy (VMAT) is a shortened delivery time, which leads to improved patient comfort and possibly smaller intra-fraction movements. This study aims at a treatment planner-independent comparison of radiotherapy treatment planning of IMRT and VMAT for head-and-neck cancer performed by several institutes and based on the same CT- and contouring data. A notable difficulty with irradiation of head-and-neck cancer (HNC) is the large number of organs at risk (OARs) in close proximity to regions with disease, including the salivary glands, spinal cord and brainstem, larynx and pharyngeal constrictors, oral mucosae, tongue and lips, masseter as well as eyes and inner ears. The challenging task for the treatment planner is to find the most optimal

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