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Title: SU-F-T-646: SBRT Lung: Moving Beyond the 3D Conformal Paradigm with An Elekta VersaHD Accelerator

Abstract

Purpose: To develop a volumetric modulated arc therapy (VMAT) planning and delivery methodology for lung stereotactic body radiation therapy (SBRT) that addresses the unique geometric challenges presented when using an Elekta VersaHD linear accelerator. Methods: The Elekta VersaHD imaging panels are fixed at 160cm SID when deployed, limiting the ability to perform non-coplanar treatments due to collisions with the treatment table. The panels can be folded in a stored position for non-coplanar treatments, but in this configuration, longitudinal table travel is restricted by the space required for the folded panels. To overcome these design features, a non-coplanar VMAT technique was designed and evaluated for 6 patients that uses a superiorly placed isocenter near the apex of the lung. A coplanar VMAT technique with isocenter placement within the target was also assessed for each patient. Non-coplanar plans included three arcs, totalling 340° of arc angle, while coplanar plans included two arcs, totalling 280° of arc angle. Each technique avoided the contralateral lung and major overlap on patient skin. Corresponding 3DCRT plans were used as a baseline for each patient in evaluating VMAT plans. Results: Coplanar and noncoplanar VMAT plans yielded a high dose conformity index (CI) improvement of 6% and lowmore » dose CI improvements of 9% and 11%, respectively, over corresponding 3DCRT plans. While both VMAT techniques provided greater skin sparing compared to 3DCRT, the non-coplanar technique offered an improvement of 20% over the coplanar approach. Treatment time with for VMAT was ∼2.5 minutes compared to ∼10 minutes for 3DCRT. Conclusion: Two VMAT techniques were developed for lung SBRT that account for machine design limitations and provide greater dose conformity and normal tissue sparing than 3DCRT plans. The non-coplanar VMAT plans showed a marginal improvement over coplanar VMAT plans and may not warrant the additional complexity.« less

Authors:
; ; ; ;  [1]
  1. University of Iowa Hospitals and Clinics, Iowa City, IA (United States)
Publication Date:
OSTI Identifier:
22649204
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 61 RADIATION PROTECTION AND DOSIMETRY; BIOMEDICAL RADIOGRAPHY; DESIGN; DOSES; LINEAR ACCELERATORS; LUNGS; PATIENTS; PLANNING; RADIOTHERAPY

Citation Formats

Dalhart, A, Hyer, D, Allen, B, Flynn, R, and Johnston, H. SU-F-T-646: SBRT Lung: Moving Beyond the 3D Conformal Paradigm with An Elekta VersaHD Accelerator. United States: N. p., 2016. Web. doi:10.1118/1.4956831.
Dalhart, A, Hyer, D, Allen, B, Flynn, R, & Johnston, H. SU-F-T-646: SBRT Lung: Moving Beyond the 3D Conformal Paradigm with An Elekta VersaHD Accelerator. United States. doi:10.1118/1.4956831.
Dalhart, A, Hyer, D, Allen, B, Flynn, R, and Johnston, H. Wed . "SU-F-T-646: SBRT Lung: Moving Beyond the 3D Conformal Paradigm with An Elekta VersaHD Accelerator". United States. doi:10.1118/1.4956831.
@article{osti_22649204,
title = {SU-F-T-646: SBRT Lung: Moving Beyond the 3D Conformal Paradigm with An Elekta VersaHD Accelerator},
author = {Dalhart, A and Hyer, D and Allen, B and Flynn, R and Johnston, H},
abstractNote = {Purpose: To develop a volumetric modulated arc therapy (VMAT) planning and delivery methodology for lung stereotactic body radiation therapy (SBRT) that addresses the unique geometric challenges presented when using an Elekta VersaHD linear accelerator. Methods: The Elekta VersaHD imaging panels are fixed at 160cm SID when deployed, limiting the ability to perform non-coplanar treatments due to collisions with the treatment table. The panels can be folded in a stored position for non-coplanar treatments, but in this configuration, longitudinal table travel is restricted by the space required for the folded panels. To overcome these design features, a non-coplanar VMAT technique was designed and evaluated for 6 patients that uses a superiorly placed isocenter near the apex of the lung. A coplanar VMAT technique with isocenter placement within the target was also assessed for each patient. Non-coplanar plans included three arcs, totalling 340° of arc angle, while coplanar plans included two arcs, totalling 280° of arc angle. Each technique avoided the contralateral lung and major overlap on patient skin. Corresponding 3DCRT plans were used as a baseline for each patient in evaluating VMAT plans. Results: Coplanar and noncoplanar VMAT plans yielded a high dose conformity index (CI) improvement of 6% and low dose CI improvements of 9% and 11%, respectively, over corresponding 3DCRT plans. While both VMAT techniques provided greater skin sparing compared to 3DCRT, the non-coplanar technique offered an improvement of 20% over the coplanar approach. Treatment time with for VMAT was ∼2.5 minutes compared to ∼10 minutes for 3DCRT. Conclusion: Two VMAT techniques were developed for lung SBRT that account for machine design limitations and provide greater dose conformity and normal tissue sparing than 3DCRT plans. The non-coplanar VMAT plans showed a marginal improvement over coplanar VMAT plans and may not warrant the additional complexity.},
doi = {10.1118/1.4956831},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2016},
month = {Wed Jun 15 00:00:00 EDT 2016}
}