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Biological equivalence between LDR and PDR in cervical cancer: multifactor analysis using the linear-quadratic model

PURPOSE: The purpose of this work was the biological comparison between Low Dose Rate (LDR) and Pulsed Dose Rate (PDR) in cervical cancer regarding the discontinuation of the afterloading system used for the LDR treatments at our Institution since December 2009. MATERIAL AND METHODS: In the first ph...

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Autores principales: Couto, José Guilherme, Bravo, Isabel, Pirraco, Rui
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Termedia Publishing House 2011
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3551353/
https://www.ncbi.nlm.nih.gov/pubmed/23346123
http://dx.doi.org/10.5114/jcb.2011.24820
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author Couto, José Guilherme
Bravo, Isabel
Pirraco, Rui
author_facet Couto, José Guilherme
Bravo, Isabel
Pirraco, Rui
author_sort Couto, José Guilherme
collection PubMed
description PURPOSE: The purpose of this work was the biological comparison between Low Dose Rate (LDR) and Pulsed Dose Rate (PDR) in cervical cancer regarding the discontinuation of the afterloading system used for the LDR treatments at our Institution since December 2009. MATERIAL AND METHODS: In the first phase we studied the influence of the pulse dose and the pulse time in the biological equivalence between LDR and PDR treatments using the Linear Quadratic Model (LQM). In the second phase, the equivalent dose in 2 Gy/fraction (EQD(2)) for the tumor, rectum and bladder in treatments performed with both techniques was evaluated and statistically compared. All evaluated patients had stage IIB cervical cancer and were treated with External Beam Radiotherapy (EBRT) plus two Brachytherapy (BT) applications. Data were collected from 48 patients (26 patients treated with LDR and 22 patients with PDR). RESULTS: In the analyses of the influence of PDR parameters in the biological equivalence between LDR and PDR treatments (Phase 1), it was calculated that if the pulse dose in PDR was kept equal to the LDR dose rate, a small the-rapeutic loss was expected. If the pulse dose was decreased, the therapeutic window became larger, but a correction in the prescribed dose was necessary. In PDR schemes with 1 hour interval between pulses, the pulse time did not influence significantly the equivalent dose. In the comparison between the groups treated with LDR and PDR (Phase 2) we concluded that they were not equivalent, because in the PDR group the total EQD(2) for the tumor, rectum and bladder was smaller than in the LDR group; the LQM estimated that a correction in the prescribed dose of 6% to 10% was ne-cessary to avoid therapeutic loss. CONCLUSIONS: A correction in the prescribed dose was necessary; this correction should be achieved by calculating the PDR dose equivalent to the desired LDR total dose.
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spelling pubmed-35513532013-01-23 Biological equivalence between LDR and PDR in cervical cancer: multifactor analysis using the linear-quadratic model Couto, José Guilherme Bravo, Isabel Pirraco, Rui J Contemp Brachytherapy Original Article PURPOSE: The purpose of this work was the biological comparison between Low Dose Rate (LDR) and Pulsed Dose Rate (PDR) in cervical cancer regarding the discontinuation of the afterloading system used for the LDR treatments at our Institution since December 2009. MATERIAL AND METHODS: In the first phase we studied the influence of the pulse dose and the pulse time in the biological equivalence between LDR and PDR treatments using the Linear Quadratic Model (LQM). In the second phase, the equivalent dose in 2 Gy/fraction (EQD(2)) for the tumor, rectum and bladder in treatments performed with both techniques was evaluated and statistically compared. All evaluated patients had stage IIB cervical cancer and were treated with External Beam Radiotherapy (EBRT) plus two Brachytherapy (BT) applications. Data were collected from 48 patients (26 patients treated with LDR and 22 patients with PDR). RESULTS: In the analyses of the influence of PDR parameters in the biological equivalence between LDR and PDR treatments (Phase 1), it was calculated that if the pulse dose in PDR was kept equal to the LDR dose rate, a small the-rapeutic loss was expected. If the pulse dose was decreased, the therapeutic window became larger, but a correction in the prescribed dose was necessary. In PDR schemes with 1 hour interval between pulses, the pulse time did not influence significantly the equivalent dose. In the comparison between the groups treated with LDR and PDR (Phase 2) we concluded that they were not equivalent, because in the PDR group the total EQD(2) for the tumor, rectum and bladder was smaller than in the LDR group; the LQM estimated that a correction in the prescribed dose of 6% to 10% was ne-cessary to avoid therapeutic loss. CONCLUSIONS: A correction in the prescribed dose was necessary; this correction should be achieved by calculating the PDR dose equivalent to the desired LDR total dose. Termedia Publishing House 2011-09-30 2011-09 /pmc/articles/PMC3551353/ /pubmed/23346123 http://dx.doi.org/10.5114/jcb.2011.24820 Text en Copyright © 2011 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 Article
Couto, José Guilherme
Bravo, Isabel
Pirraco, Rui
Biological equivalence between LDR and PDR in cervical cancer: multifactor analysis using the linear-quadratic model
title Biological equivalence between LDR and PDR in cervical cancer: multifactor analysis using the linear-quadratic model
title_full Biological equivalence between LDR and PDR in cervical cancer: multifactor analysis using the linear-quadratic model
title_fullStr Biological equivalence between LDR and PDR in cervical cancer: multifactor analysis using the linear-quadratic model
title_full_unstemmed Biological equivalence between LDR and PDR in cervical cancer: multifactor analysis using the linear-quadratic model
title_short Biological equivalence between LDR and PDR in cervical cancer: multifactor analysis using the linear-quadratic model
title_sort biological equivalence between ldr and pdr in cervical cancer: multifactor analysis using the linear-quadratic model
topic Original Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3551353/
https://www.ncbi.nlm.nih.gov/pubmed/23346123
http://dx.doi.org/10.5114/jcb.2011.24820
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