Absorbed dose kernel and self‐shielding calculations for a novel radiopaque glass microsphere for transarterial radioembolization.
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| Title: | Absorbed dose kernel and self‐shielding calculations for a novel radiopaque glass microsphere for transarterial radioembolization. |
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| Authors: | Church, Cody1, Mawko, George2,3, Archambault, John Paul4, Lewandowski, Robert5, Liu, David6, Kehoe, Sharon7,8, Boyd, Daniel7,8, Abraham, Robert2,7, Syme, Alasdair3,9 alasdair.syme@nshealth.ca |
| Source: | Medical Physics. Feb2018, Vol. 45 Issue 2, p934-942. 9p. |
| Subjects: | Radiographic contrast media, Microspheres, Radioembolization, Nuclear medicine, Radiotherapy, Radiation dosimetry |
| Abstract: | Purpose: Radiopaque microspheres may provide intraprocedural and postprocedural feedback during transarterial radioembolization (TARE). Furthermore, the potential to use higher resolution x‐ray imaging techniques as opposed to nuclear medicine imaging suggests that significant improvements in the accuracy and precision of radiation dosimetry calculations could be realized for this type of therapy. This study investigates the absorbed dose kernel for novel radiopaque microspheres including contributions of both short and long‐lived contaminant radionuclides while concurrently quantifying the self‐shielding of the glass network. Methods: Monte Carlo simulations using EGSnrc were performed to determine the dose kernels for all monoenergetic electron emissions and all beta spectra for radionuclides reported in a neutron activation study of the microspheres. Simulations were benchmarked against an accepted 90Y dose point kernel. Self‐shielding was quantified for the microspheres by simulating an isotropically emitting, uniformly distributed source, in glass and in water. The ratio of the absorbed doses was scored as a function of distance from a microsphere. The absorbed dose kernel for the microspheres was calculated for (a) two bead formulations following (b) two different durations of neutron activation, at (c) various time points following activation. Results: Self‐shielding varies with time postremoval from the reactor. At early time points, it is less pronounced due to the higher energies of the emissions. It is on the order of 0.4–2.8% at a radial distance of 5.43 mm with increased size from 10 to 50 μm in diameter during the time that the microspheres would be administered to a patient. At long time points, self‐shielding is more pronounced and can reach values in excess of 20% near the end of the range of the emissions. Absorbed dose kernels for 90Y, 90mY, 85mSr, 85Sr, 87mSr, 89Sr, 70Ga, 72Ga, and 31Si are presented and used to determine an overall kernel for the microspheres based on weighted activities. The shapes of the absorbed dose kernels are dominated at short times postactivation by the contributions of 70Ga and 72Ga. Following decay of the short‐lived contaminants, the absorbed dose kernel is effectively that of 90Y. After approximately 1000 h postactivation, the contributions of 85Sr and 89Sr become increasingly dominant, though the absorbed dose‐rate around the beads drops by roughly four orders of magnitude. Conclusions: The introduction of high atomic number elements for the purpose of increasing radiopacity necessarily leads to the production of radionuclides other than 90Y in the microspheres. Most of the radionuclides in this study are short‐lived and are likely not of any significant concern for this therapeutic agent. The presence of small quantities of longer lived radionuclides will change the shape of the absorbed dose kernel around a microsphere at long time points postadministration when activity levels are significantly reduced. [ABSTRACT FROM AUTHOR] |
| Copyright of Medical Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
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| Items | – Name: Title Label: Title Group: Ti Data: Absorbed dose kernel and self‐shielding calculations for a novel radiopaque glass microsphere for transarterial radioembolization. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Church%2C+Cody%22">Church, Cody</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Mawko%2C+George%22">Mawko, George</searchLink><relatesTo>2,3</relatesTo><br /><searchLink fieldCode="AR" term="%22Archambault%2C+John+Paul%22">Archambault, John Paul</searchLink><relatesTo>4</relatesTo><br /><searchLink fieldCode="AR" term="%22Lewandowski%2C+Robert%22">Lewandowski, Robert</searchLink><relatesTo>5</relatesTo><br /><searchLink fieldCode="AR" term="%22Liu%2C+David%22">Liu, David</searchLink><relatesTo>6</relatesTo><br /><searchLink fieldCode="AR" term="%22Kehoe%2C+Sharon%22">Kehoe, Sharon</searchLink><relatesTo>7,8</relatesTo><br /><searchLink fieldCode="AR" term="%22Boyd%2C+Daniel%22">Boyd, Daniel</searchLink><relatesTo>7,8</relatesTo><br /><searchLink fieldCode="AR" term="%22Abraham%2C+Robert%22">Abraham, Robert</searchLink><relatesTo>2,7</relatesTo><br /><searchLink fieldCode="AR" term="%22Syme%2C+Alasdair%22">Syme, Alasdair</searchLink><relatesTo>3,9</relatesTo><i> alasdair.syme@nshealth.ca</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Medical+Physics%22">Medical Physics</searchLink>. Feb2018, Vol. 45 Issue 2, p934-942. 9p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Radiographic+contrast+media%22">Radiographic contrast media</searchLink><br /><searchLink fieldCode="DE" term="%22Microspheres%22">Microspheres</searchLink><br /><searchLink fieldCode="DE" term="%22Radioembolization%22">Radioembolization</searchLink><br /><searchLink fieldCode="DE" term="%22Nuclear+medicine%22">Nuclear medicine</searchLink><br /><searchLink fieldCode="DE" term="%22Radiotherapy%22">Radiotherapy</searchLink><br /><searchLink fieldCode="DE" term="%22Radiation+dosimetry%22">Radiation dosimetry</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Purpose: Radiopaque microspheres may provide intraprocedural and postprocedural feedback during transarterial radioembolization (TARE). Furthermore, the potential to use higher resolution x‐ray imaging techniques as opposed to nuclear medicine imaging suggests that significant improvements in the accuracy and precision of radiation dosimetry calculations could be realized for this type of therapy. This study investigates the absorbed dose kernel for novel radiopaque microspheres including contributions of both short and long‐lived contaminant radionuclides while concurrently quantifying the self‐shielding of the glass network. Methods: Monte Carlo simulations using EGSnrc were performed to determine the dose kernels for all monoenergetic electron emissions and all beta spectra for radionuclides reported in a neutron activation study of the microspheres. Simulations were benchmarked against an accepted 90Y dose point kernel. Self‐shielding was quantified for the microspheres by simulating an isotropically emitting, uniformly distributed source, in glass and in water. The ratio of the absorbed doses was scored as a function of distance from a microsphere. The absorbed dose kernel for the microspheres was calculated for (a) two bead formulations following (b) two different durations of neutron activation, at (c) various time points following activation. Results: Self‐shielding varies with time postremoval from the reactor. At early time points, it is less pronounced due to the higher energies of the emissions. It is on the order of 0.4–2.8% at a radial distance of 5.43 mm with increased size from 10 to 50 μm in diameter during the time that the microspheres would be administered to a patient. At long time points, self‐shielding is more pronounced and can reach values in excess of 20% near the end of the range of the emissions. Absorbed dose kernels for 90Y, 90mY, 85mSr, 85Sr, 87mSr, 89Sr, 70Ga, 72Ga, and 31Si are presented and used to determine an overall kernel for the microspheres based on weighted activities. The shapes of the absorbed dose kernels are dominated at short times postactivation by the contributions of 70Ga and 72Ga. Following decay of the short‐lived contaminants, the absorbed dose kernel is effectively that of 90Y. After approximately 1000 h postactivation, the contributions of 85Sr and 89Sr become increasingly dominant, though the absorbed dose‐rate around the beads drops by roughly four orders of magnitude. Conclusions: The introduction of high atomic number elements for the purpose of increasing radiopacity necessarily leads to the production of radionuclides other than 90Y in the microspheres. Most of the radionuclides in this study are short‐lived and are likely not of any significant concern for this therapeutic agent. The presence of small quantities of longer lived radionuclides will change the shape of the absorbed dose kernel around a microsphere at long time points postadministration when activity levels are significantly reduced. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Medical Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1002/mp.12717 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 9 StartPage: 934 Subjects: – SubjectFull: Radiographic contrast media Type: general – SubjectFull: Microspheres Type: general – SubjectFull: Radioembolization Type: general – SubjectFull: Nuclear medicine Type: general – SubjectFull: Radiotherapy Type: general – SubjectFull: Radiation dosimetry Type: general Titles: – TitleFull: Absorbed dose kernel and self‐shielding calculations for a novel radiopaque glass microsphere for transarterial radioembolization. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Church, Cody – PersonEntity: Name: NameFull: Mawko, George – PersonEntity: Name: NameFull: Archambault, John Paul – PersonEntity: Name: NameFull: Lewandowski, Robert – PersonEntity: Name: NameFull: Liu, David – PersonEntity: Name: NameFull: Kehoe, Sharon – PersonEntity: Name: NameFull: Boyd, Daniel – PersonEntity: Name: NameFull: Abraham, Robert – PersonEntity: Name: NameFull: Syme, Alasdair IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 02 Text: Feb2018 Type: published Y: 2018 Identifiers: – Type: issn-print Value: 00942405 Numbering: – Type: volume Value: 45 – Type: issue Value: 2 Titles: – TitleFull: Medical Physics Type: main |
| ResultId | 1 |
