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Small-scale dosimetry for alpha particle (241)Am source cell irradiation and estimation of γ-H2AX foci distribution in prostate cancer cell line PC3

BACKGROUND: The development of new targeted alpha therapies motivates improving alpha particle dosimetry. For alpha particles, microscopic targets must be considered to estimate dosimetric quantities that can predict the biological response. As double-strand breaks (DSB) on DNA are the main cause of...

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Autores principales: Mellhammar, Emma, Dahlbom, Magnus, Vilhelmsson-Timmermand, Oskar, Strand, Sven-Erik
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Springer International Publishing 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9296737/
https://www.ncbi.nlm.nih.gov/pubmed/35852717
http://dx.doi.org/10.1186/s40658-022-00475-x
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author Mellhammar, Emma
Dahlbom, Magnus
Vilhelmsson-Timmermand, Oskar
Strand, Sven-Erik
author_facet Mellhammar, Emma
Dahlbom, Magnus
Vilhelmsson-Timmermand, Oskar
Strand, Sven-Erik
author_sort Mellhammar, Emma
collection PubMed
description BACKGROUND: The development of new targeted alpha therapies motivates improving alpha particle dosimetry. For alpha particles, microscopic targets must be considered to estimate dosimetric quantities that can predict the biological response. As double-strand breaks (DSB) on DNA are the main cause of cell death by ionizing radiation, cell nuclei are relevant volumes necessary to consider as targets. Since a large variance is expected of alpha particle hits in individual cell nuclei irradiated by an uncollimated alpha-emitting source, the damage induced should have a similar distribution. The induction of DSB can be measured by immunofluorescent γ-H2AX staining. The cell γ-H2AX foci distribution and alpha particle hits distribution should be comparable and thereby verify the necessity to consider the relevant dosimetric volumes. METHODS: A Monte Carlo simulation model of an (241)Am source alpha particle irradiation setup was combined with two versions of realistic cell nuclei phantoms. These were generated from DAPI-stained PC3 cells imaged with fluorescent microscopy, one consisting of elliptical cylinders and the other of segmented mesh volumes. PC3 cells were irradiated with the (241)Am source for 4, 8 and 12 min, and after 30 min fixated and stained with immunofluorescent γ-H2AX marker. The detected radiation-induced foci (RIF) were compared to simulated RIF. RESULTS: The mesh volume phantom detected a higher mean of alpha particle hits and energy imparted (MeV) per cell nuclei than the elliptical cylinder phantom, but the mean specific energy (Gy) was very similar. The mesh volume phantom detected a slightly larger variance between individual cells, stemming from the more extreme and less continuous distribution of cell nuclei sizes represented in this phantom. The simulated RIF distribution from both phantoms was in good agreement with the detected RIF, although the detected distribution had a zero-inflated shape not seen in the simulated distributions. An estimate of undetected foci was used to correct the detected RIF distribution and improved the agreement with the simulations. CONCLUSION: Two methods to generate cell nuclei phantoms for Monte Carlo dosimetry simulations were tested and generated similar results. The simulated and detected RIF distributions from alpha particle-irradiated PC3 cells were in good agreement, proposing the necessity to consider microscopic targets in alpha particle dosimetry. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40658-022-00475-x.
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spelling pubmed-92967372022-07-21 Small-scale dosimetry for alpha particle (241)Am source cell irradiation and estimation of γ-H2AX foci distribution in prostate cancer cell line PC3 Mellhammar, Emma Dahlbom, Magnus Vilhelmsson-Timmermand, Oskar Strand, Sven-Erik EJNMMI Phys Original Research BACKGROUND: The development of new targeted alpha therapies motivates improving alpha particle dosimetry. For alpha particles, microscopic targets must be considered to estimate dosimetric quantities that can predict the biological response. As double-strand breaks (DSB) on DNA are the main cause of cell death by ionizing radiation, cell nuclei are relevant volumes necessary to consider as targets. Since a large variance is expected of alpha particle hits in individual cell nuclei irradiated by an uncollimated alpha-emitting source, the damage induced should have a similar distribution. The induction of DSB can be measured by immunofluorescent γ-H2AX staining. The cell γ-H2AX foci distribution and alpha particle hits distribution should be comparable and thereby verify the necessity to consider the relevant dosimetric volumes. METHODS: A Monte Carlo simulation model of an (241)Am source alpha particle irradiation setup was combined with two versions of realistic cell nuclei phantoms. These were generated from DAPI-stained PC3 cells imaged with fluorescent microscopy, one consisting of elliptical cylinders and the other of segmented mesh volumes. PC3 cells were irradiated with the (241)Am source for 4, 8 and 12 min, and after 30 min fixated and stained with immunofluorescent γ-H2AX marker. The detected radiation-induced foci (RIF) were compared to simulated RIF. RESULTS: The mesh volume phantom detected a higher mean of alpha particle hits and energy imparted (MeV) per cell nuclei than the elliptical cylinder phantom, but the mean specific energy (Gy) was very similar. The mesh volume phantom detected a slightly larger variance between individual cells, stemming from the more extreme and less continuous distribution of cell nuclei sizes represented in this phantom. The simulated RIF distribution from both phantoms was in good agreement with the detected RIF, although the detected distribution had a zero-inflated shape not seen in the simulated distributions. An estimate of undetected foci was used to correct the detected RIF distribution and improved the agreement with the simulations. CONCLUSION: Two methods to generate cell nuclei phantoms for Monte Carlo dosimetry simulations were tested and generated similar results. The simulated and detected RIF distributions from alpha particle-irradiated PC3 cells were in good agreement, proposing the necessity to consider microscopic targets in alpha particle dosimetry. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40658-022-00475-x. Springer International Publishing 2022-07-19 /pmc/articles/PMC9296737/ /pubmed/35852717 http://dx.doi.org/10.1186/s40658-022-00475-x Text en © The Author(s) 2022 https://creativecommons.org/licenses/by/4.0/Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Original Research
Mellhammar, Emma
Dahlbom, Magnus
Vilhelmsson-Timmermand, Oskar
Strand, Sven-Erik
Small-scale dosimetry for alpha particle (241)Am source cell irradiation and estimation of γ-H2AX foci distribution in prostate cancer cell line PC3
title Small-scale dosimetry for alpha particle (241)Am source cell irradiation and estimation of γ-H2AX foci distribution in prostate cancer cell line PC3
title_full Small-scale dosimetry for alpha particle (241)Am source cell irradiation and estimation of γ-H2AX foci distribution in prostate cancer cell line PC3
title_fullStr Small-scale dosimetry for alpha particle (241)Am source cell irradiation and estimation of γ-H2AX foci distribution in prostate cancer cell line PC3
title_full_unstemmed Small-scale dosimetry for alpha particle (241)Am source cell irradiation and estimation of γ-H2AX foci distribution in prostate cancer cell line PC3
title_short Small-scale dosimetry for alpha particle (241)Am source cell irradiation and estimation of γ-H2AX foci distribution in prostate cancer cell line PC3
title_sort small-scale dosimetry for alpha particle (241)am source cell irradiation and estimation of γ-h2ax foci distribution in prostate cancer cell line pc3
topic Original Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9296737/
https://www.ncbi.nlm.nih.gov/pubmed/35852717
http://dx.doi.org/10.1186/s40658-022-00475-x
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