Application of AAPM TG 119 to volumetric arc therapy (VMAT)

Dinesh Kumar Mynampati,Ravindra Yaparpalvi,Dennis Mah,Linda Hong,Hsiang‐Chi Kuo

doi:10.1120/jacmp.v13i5.3382

Dinesh Kumar Mynampati, Ravindra Yaparpalvi + Show 3 more

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https://doi.org/10.1120/jacmp.v13i5.3382

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Abstract

The purpose of this study was to create AAPM TG 119 benchmark plans for volumetric arc therapy (VMAT) and to compare VMAT plans with IMRT plan data. AAPM TG 119 proposes a set of test clinical cases for testing the accuracy of IMRT planning and delivery system. For these test cases, we generated two treatment plans, the first plan using 7–9 static dMLC IMRT fields and a second plan utilizing one‐ or two‐arc VMAT technique. Dose optimization and calculations performed using 6 MV photons and Eclipse treatment planning system. Dose prescription and planning objectives were set according to the TG 119 goals. Plans were scored based on TG 119 planning objectives. Treatment plans were compared using conformity index (CI) for reference dose and homogeneity index (HI) (for D5‐D95). F or test cases prostate, head‐and‐neck, C‐shape and multitarget prescription dose are 75.6 Gy, 50.4 Gy, 50 Gy and 50 Gy, respectively. VMAT dose distributions were comparable to dMLC IMRT plans. Our planning results matched TG 119 planning results. For treatment plans studied, conformity indices ranged from 1.05–1.23 (IMRT) and 1.04–1.23 (VMAT). Homogeneity indices ranged from 4.6%–11.0% (IMRT) and 4.6%–10.5% (VMAT). The ratio of total monitor units necessary for dMLC IMRT to that of VMAT was in the range of 1.1–2.0. AAPM TG 119 test cases are useful to generate VMAT benchmark plans. At preclinical implementation stage, plan comparison of VMAT and IMRT plans of AAPM TG 119 test case allowed us to understand basic capabilities of VMAT technique.PACS number: 87.55.Qr

Highlights

The advantage of nonuniform beams is to deliver highly conformal distributions to target, while sparing organs at risk has led to improvements in clinical outcomes
We provide our experience applying AAPM, Task Group (TG) 119 to volumetric arc therapy (VMAT) technology
The goal of our work is to determine if VMAT is capable of delivering plans of comparable quality compared to IMRT plans using TG 119 as a metric

Summary

Introduction

The advantage of nonuniform beams is to deliver highly conformal distributions to target, while sparing organs at risk has led to improvements in clinical outcomes. The concept of volumetric modulated arc therapy (VMAT) was first proposed in 1995.(2) More recently the work of Otto[3] has led to the development of a commercial approach of VMAT called RapidArc (Varian Medical Systems, Palo Alto, CA). The architecture of this technique provides more number of degrees of freedom to optimize the dose delivery. Clinical advantages and comparison with present techniques for different sites have been reported.[4,5,6] To commission and QA the delivery system, Ling et al[7] proposed benchmark tests based upon the principles addressed by LoSasso et al[8]

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