A dosimetric comparison of three-dimensional conformal radiotherapy, volumetric-modulated arc therapy, and dynamic conformal arc therapy in the treatment of non-small cell lung cancer using stereotactic body radiotherapy.

Bradley M Rauschenbach,Harish K Malhotra,Luke Mackowiak

doi:10.1120/jacmp.v15i5.4898

Bradley M Rauschenbach, Harish K Malhotra + Show 1 more

Open Access

https://doi.org/10.1120/jacmp.v15i5.4898

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Abstract

This study evaluates three‐dimensional conformal radiotherapy (3D CRT), volumetric‐ modulated arc therapy (VMAT), and dynamic conformal arc therapy (DCAT) planning techniques using dosimetric indices from Radiation Therapy Oncology Group (RTOG) protocols 0236, 0813, and 0915 for the treatment of early‐stage non‐small cell lung cancer (NSCLC) using stereotactic body radiotherapy (SBRT). Twenty‐five clinical patients, five per lung lobe, previously treated for NSCLC using 3D CRT SBRT under respective RTOG protocols were replanned with VMAT and DCAT techniques. All plans were compared using respective RTOG dosimetric indices. High‐ and low‐dose spillage improved for VMAT and DCAT plans, though only VMAT was able to improve dose to all organs at risk (OARs). DCAT was only able to provide a minimal improvement in dose to the heart and ipsilateral brachial plexus. Mean bilateral, contralateral, and V20 (percentage of bilateral lung receiving at least 20 Gy dose) doses were reduced with VMAT in comparison with respective 3D CRT clinical plans. Though some of the DCAT plans had values for the above indices slightly higher than their respective 3D CRT plans, they still were able to meet the RTOG constraints. VMAT and DCAT were able to offer improved skin dose by 1.1% and 11%, respectively. Monitor units required for treatment delivery increased with VMAT by 41%, but decreased with DCAT by 26%. VMAT and DCAT provided improved dose distributions to the PTV, but only VMAT was consistently superior in sparing dose to OARs in all the five lobes. DCAT should still remain an alternative to 3D CRT in facilities that do not have VMAT or intensity‐modulated radiotherapy (IMRT) capabilities.PACS numbers: 87.53.Ly, 87.55.dk, 87.55.D‐

Highlights

148 Rauschenbach et al.: Comparison of 3D CRT, volumetric-modulated arc therapy (VMAT) vs. dynamic conformal arc therapy (DCAT) for non-small cell lung cancer (NSCLC) using stereotactic body radiotherapy (SBRT)hypofractionation regimen is becoming popular, delivering a very high ablative radiation dose per fraction in 1 to 5 fractions
Skin dose improved with DCAT by 11% and by 1.1% with VMAT
VMAT has been previously reported to achieve superior conformal plans when compared to 3D CRT and DCAT.[12]. The rotating arcs associated with VMAT and DCAT are more effective at conforming dose to spherical planning target volume (PTV) than multiple static beams

Summary

Introduction

148 Rauschenbach et al.: Comparison of 3D CRT, VMAT vs. DCAT for NSCLC using SBRThypofractionation regimen is becoming popular, delivering a very high ablative radiation dose per fraction in 1 to 5 fractions. SBRT is quickly becoming a standard treatment option over conventional fractionation for patients with medically inoperable early-stage NSCLC. Many institutions deliver SBRT using three-dimensional conformal radiotherapy (3D CRT), involving the use of seven to eleven static, nonopposing, coplanar, and noncoplanar beams with approximately equal weightings. This popular method results in a highly conformal dose distribution surrounding the tumor in all directions. A new generation of linear accelerators supports radiation dose delivery using volumetric-modulated arc therapy (VMAT) and dynamic conformal arc therapy (DCAT). Both treatment techniques are capable of expediting the treatment delivery process significantly

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