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Dosimetric impacts of applicator displacements and applicator reconstruction-uncertainties on 3D image-guided brachytherapy for cervical cancer

PURPOSE: To quantify the dosimetric impact of applicator displacements and applicator reconstruction-uncertainties through simulated planning studies of virtual applicator shifts. MATERIAL AND METHODS: Twenty randomly selected high-dose-rate (HDR) titanium tandem-and-ovoid (T&O) plans were retro...

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Autores principales: Schindel, Joshua, Zhang, Winson, Bhatia, Sudershan K., Sun, Wenqing, Kim, Yusung
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Termedia Publishing House 2013
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3899640/
https://www.ncbi.nlm.nih.gov/pubmed/24474977
http://dx.doi.org/10.5114/jcb.2013.39453
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author Schindel, Joshua
Zhang, Winson
Bhatia, Sudershan K.
Sun, Wenqing
Kim, Yusung
author_facet Schindel, Joshua
Zhang, Winson
Bhatia, Sudershan K.
Sun, Wenqing
Kim, Yusung
author_sort Schindel, Joshua
collection PubMed
description PURPOSE: To quantify the dosimetric impact of applicator displacements and applicator reconstruction-uncertainties through simulated planning studies of virtual applicator shifts. MATERIAL AND METHODS: Twenty randomly selected high-dose-rate (HDR) titanium tandem-and-ovoid (T&O) plans were retrospectively studied. MRI-guided, conformal brachytherapy (MRIG-CBT) plans were retrospectively generated. To simulate T&O displacement, the whole T&O set was virtually shifted on treatment planning system in the cranial (+) and the caudal (–) direction after each dose calculation. Each shifted plan was compared to an unshifted plan. To simulate T&O reconstruction-uncertainties, each tandem and ovoid was separately shifted along its axis before performing the dose calculation. After the dose calculation, the calculated isodose lines and T&O were moved back to unshifted T&O position. Shifted and shifted-back plan were compared. RESULTS: Regarding the dosimetric impact of the simulated T&O displacements, rectal D(2cc) values were observed as being the most sensitive to change due to T&O displacement among all dosimetric metrics regardless of point A (p < 0.013) or MRIG-CBT plans (p < 0.0277). To avoid more than 10% change, ± 1.5 mm T&O displacements were accommodated for both point A and MRIG-CBT plans. The dosimetric impact of T&O displacements on sigmoid (p < 0.0005), bladder (p < 0.0001), HR-CTV (p < 0.0036), and point A (p < 0.0015) were significantly larger in the MRIG-CBT plans than point A plans. Regarding the dosimetric impact of T&O reconstruction-uncertainties, less than ± 3.0 mm reconstruction-uncertainties were also required in order to avoid more than 10% dosimetric change in either the point A or MRIG-CBT plans. CONCLUSIONS: The dosimetric impact of simulated T&O displacements was significantly larger in the MRIG-CBT plans than in the point A plans. Either ± 3 mm T&O displacement or a ± 4.5 mm T&O reconstruction-uncertainty could cause greater than 10% dosimetric change for both point A plans and MRIG-CBT plans.
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spelling pubmed-38996402014-01-28 Dosimetric impacts of applicator displacements and applicator reconstruction-uncertainties on 3D image-guided brachytherapy for cervical cancer Schindel, Joshua Zhang, Winson Bhatia, Sudershan K. Sun, Wenqing Kim, Yusung J Contemp Brachytherapy Original Paper PURPOSE: To quantify the dosimetric impact of applicator displacements and applicator reconstruction-uncertainties through simulated planning studies of virtual applicator shifts. MATERIAL AND METHODS: Twenty randomly selected high-dose-rate (HDR) titanium tandem-and-ovoid (T&O) plans were retrospectively studied. MRI-guided, conformal brachytherapy (MRIG-CBT) plans were retrospectively generated. To simulate T&O displacement, the whole T&O set was virtually shifted on treatment planning system in the cranial (+) and the caudal (–) direction after each dose calculation. Each shifted plan was compared to an unshifted plan. To simulate T&O reconstruction-uncertainties, each tandem and ovoid was separately shifted along its axis before performing the dose calculation. After the dose calculation, the calculated isodose lines and T&O were moved back to unshifted T&O position. Shifted and shifted-back plan were compared. RESULTS: Regarding the dosimetric impact of the simulated T&O displacements, rectal D(2cc) values were observed as being the most sensitive to change due to T&O displacement among all dosimetric metrics regardless of point A (p < 0.013) or MRIG-CBT plans (p < 0.0277). To avoid more than 10% change, ± 1.5 mm T&O displacements were accommodated for both point A and MRIG-CBT plans. The dosimetric impact of T&O displacements on sigmoid (p < 0.0005), bladder (p < 0.0001), HR-CTV (p < 0.0036), and point A (p < 0.0015) were significantly larger in the MRIG-CBT plans than point A plans. Regarding the dosimetric impact of T&O reconstruction-uncertainties, less than ± 3.0 mm reconstruction-uncertainties were also required in order to avoid more than 10% dosimetric change in either the point A or MRIG-CBT plans. CONCLUSIONS: The dosimetric impact of simulated T&O displacements was significantly larger in the MRIG-CBT plans than in the point A plans. Either ± 3 mm T&O displacement or a ± 4.5 mm T&O reconstruction-uncertainty could cause greater than 10% dosimetric change for both point A plans and MRIG-CBT plans. Termedia Publishing House 2013-12-18 2013-12 /pmc/articles/PMC3899640/ /pubmed/24474977 http://dx.doi.org/10.5114/jcb.2013.39453 Text en Copyright © 2013 Termedia http://creativecommons.org/licenses/by-nc-nd/3.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution-Noncommercial 3.0 Unported License, permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Paper
Schindel, Joshua
Zhang, Winson
Bhatia, Sudershan K.
Sun, Wenqing
Kim, Yusung
Dosimetric impacts of applicator displacements and applicator reconstruction-uncertainties on 3D image-guided brachytherapy for cervical cancer
title Dosimetric impacts of applicator displacements and applicator reconstruction-uncertainties on 3D image-guided brachytherapy for cervical cancer
title_full Dosimetric impacts of applicator displacements and applicator reconstruction-uncertainties on 3D image-guided brachytherapy for cervical cancer
title_fullStr Dosimetric impacts of applicator displacements and applicator reconstruction-uncertainties on 3D image-guided brachytherapy for cervical cancer
title_full_unstemmed Dosimetric impacts of applicator displacements and applicator reconstruction-uncertainties on 3D image-guided brachytherapy for cervical cancer
title_short Dosimetric impacts of applicator displacements and applicator reconstruction-uncertainties on 3D image-guided brachytherapy for cervical cancer
title_sort dosimetric impacts of applicator displacements and applicator reconstruction-uncertainties on 3d image-guided brachytherapy for cervical cancer
topic Original Paper
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3899640/
https://www.ncbi.nlm.nih.gov/pubmed/24474977
http://dx.doi.org/10.5114/jcb.2013.39453
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