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The choice of statistical methods for comparisons of dosimetric data in radiotherapy

PURPOSE: Novel irradiation techniques are continuously introduced in radiotherapy to optimize the accuracy, the security and the clinical outcome of treatments. These changes could raise the question of discontinuity in dosimetric presentation and the subsequent need for practice adjustments in case...

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Autores principales: Chaikh, Abdulhamid, Giraud, Jean-Yves, Perrin, Emmanuel, Bresciani, Jean-Pierre, Balosso, Jacques
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4261592/
https://www.ncbi.nlm.nih.gov/pubmed/25231199
http://dx.doi.org/10.1186/1748-717X-9-205
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author Chaikh, Abdulhamid
Giraud, Jean-Yves
Perrin, Emmanuel
Bresciani, Jean-Pierre
Balosso, Jacques
author_facet Chaikh, Abdulhamid
Giraud, Jean-Yves
Perrin, Emmanuel
Bresciani, Jean-Pierre
Balosso, Jacques
author_sort Chaikh, Abdulhamid
collection PubMed
description PURPOSE: Novel irradiation techniques are continuously introduced in radiotherapy to optimize the accuracy, the security and the clinical outcome of treatments. These changes could raise the question of discontinuity in dosimetric presentation and the subsequent need for practice adjustments in case of significant modifications. This study proposes a comprehensive approach to compare different techniques and tests whether their respective dose calculation algorithms give rise to statistically significant differences in the treatment doses for the patient. METHODS: Statistical investigation principles are presented in the framework of a clinical example based on 62 fields of radiotherapy for lung cancer. The delivered doses in monitor units were calculated using three different dose calculation methods: the reference method accounts the dose without tissues density corrections using Pencil Beam Convolution (PBC) algorithm, whereas new methods calculate the dose with tissues density correction for 1D and 3D using Modified Batho (MB) method and Equivalent Tissue air ratio (ETAR) method, respectively. The normality of the data and the homogeneity of variance between groups were tested using Shapiro-Wilks and Levene test, respectively, then non-parametric statistical tests were performed. Specifically, the dose means estimated by the different calculation methods were compared using Friedman’s test and Wilcoxon signed-rank test. In addition, the correlation between the doses calculated by the three methods was assessed using Spearman’s rank and Kendall’s rank tests. RESULTS: The Friedman’s test showed a significant effect on the calculation method for the delivered dose of lung cancer patients (p <0.001). The density correction methods yielded to lower doses as compared to PBC by on average (−5 ± 4.4 SD) for MB and (−4.7 ± 5 SD) for ETAR. Post-hoc Wilcoxon signed-rank test of paired comparisons indicated that the delivered dose was significantly reduced using density-corrected methods as compared to the reference method. Spearman’s and Kendall’s rank tests indicated a positive correlation between the doses calculated with the different methods. CONCLUSION: This paper illustrates and justifies the use of statistical tests and graphical representations for dosimetric comparisons in radiotherapy. The statistical analysis shows the significance of dose differences resulting from two or more techniques in radiotherapy.
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spelling pubmed-42615922014-12-10 The choice of statistical methods for comparisons of dosimetric data in radiotherapy Chaikh, Abdulhamid Giraud, Jean-Yves Perrin, Emmanuel Bresciani, Jean-Pierre Balosso, Jacques Radiat Oncol Methodology PURPOSE: Novel irradiation techniques are continuously introduced in radiotherapy to optimize the accuracy, the security and the clinical outcome of treatments. These changes could raise the question of discontinuity in dosimetric presentation and the subsequent need for practice adjustments in case of significant modifications. This study proposes a comprehensive approach to compare different techniques and tests whether their respective dose calculation algorithms give rise to statistically significant differences in the treatment doses for the patient. METHODS: Statistical investigation principles are presented in the framework of a clinical example based on 62 fields of radiotherapy for lung cancer. The delivered doses in monitor units were calculated using three different dose calculation methods: the reference method accounts the dose without tissues density corrections using Pencil Beam Convolution (PBC) algorithm, whereas new methods calculate the dose with tissues density correction for 1D and 3D using Modified Batho (MB) method and Equivalent Tissue air ratio (ETAR) method, respectively. The normality of the data and the homogeneity of variance between groups were tested using Shapiro-Wilks and Levene test, respectively, then non-parametric statistical tests were performed. Specifically, the dose means estimated by the different calculation methods were compared using Friedman’s test and Wilcoxon signed-rank test. In addition, the correlation between the doses calculated by the three methods was assessed using Spearman’s rank and Kendall’s rank tests. RESULTS: The Friedman’s test showed a significant effect on the calculation method for the delivered dose of lung cancer patients (p <0.001). The density correction methods yielded to lower doses as compared to PBC by on average (−5 ± 4.4 SD) for MB and (−4.7 ± 5 SD) for ETAR. Post-hoc Wilcoxon signed-rank test of paired comparisons indicated that the delivered dose was significantly reduced using density-corrected methods as compared to the reference method. Spearman’s and Kendall’s rank tests indicated a positive correlation between the doses calculated with the different methods. CONCLUSION: This paper illustrates and justifies the use of statistical tests and graphical representations for dosimetric comparisons in radiotherapy. The statistical analysis shows the significance of dose differences resulting from two or more techniques in radiotherapy. BioMed Central 2014-09-18 /pmc/articles/PMC4261592/ /pubmed/25231199 http://dx.doi.org/10.1186/1748-717X-9-205 Text en © Chaikh et al.; licensee BioMed Central Ltd. 2014 This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Methodology
Chaikh, Abdulhamid
Giraud, Jean-Yves
Perrin, Emmanuel
Bresciani, Jean-Pierre
Balosso, Jacques
The choice of statistical methods for comparisons of dosimetric data in radiotherapy
title The choice of statistical methods for comparisons of dosimetric data in radiotherapy
title_full The choice of statistical methods for comparisons of dosimetric data in radiotherapy
title_fullStr The choice of statistical methods for comparisons of dosimetric data in radiotherapy
title_full_unstemmed The choice of statistical methods for comparisons of dosimetric data in radiotherapy
title_short The choice of statistical methods for comparisons of dosimetric data in radiotherapy
title_sort choice of statistical methods for comparisons of dosimetric data in radiotherapy
topic Methodology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4261592/
https://www.ncbi.nlm.nih.gov/pubmed/25231199
http://dx.doi.org/10.1186/1748-717X-9-205
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