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Auditore L, Pistone D, Italiano A, Amato E, Gnesin S. Monte Carlo Simulations Corroborate PET-Measured Discrepancies in Activity Assessments of Commercial 90Y Vials. J Nucl Med 2023; 64:1471-1477. [PMID: 37442605 DOI: 10.2967/jnumed.123.265494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 04/25/2023] [Indexed: 07/15/2023] Open
Abstract
In a recent multicenter study, discrepancies between PET/CT-measured activity and vendor-calibrated activity for 90Y glass and resin microspheres were found. In the present work, the origin of these discrepancies was investigated by Monte Carlo (MC) simulations. Methods: Three vial configurations, containing 90Y-chloride, 90Y-labeled glass microspheres, and 90Y-labeled resin microspheres, were modeled with GAMOS, and the electric signal generated in an activity meter was simulated. Energy deposition was scored in the activity meter-active regions and converted into electric current per unit activity. Internal bremsstrahlung (IB) photons, always accompanying β-decay, were simulated in addition to 90Y decays. The electric current per source activity obtained for 90Y glass and resin microspheres, Iglass and Iresin, was compared in terms of relative percentage difference with that of 90Y-chloride ([Formula: see text] and [Formula: see text]) and each other (δ). The findings of this work were compared with the ones obtained through PET measurements in the multicenter study. Results: With the inclusion of IB photons as primary particles in MC simulations, the [Formula: see text] and [Formula: see text] results were 24.6% ± 3.9% and -15.0% ± 2.2%, respectively, whereas δ was 46.5% ± 1.9%, in very good agreement with the values reported in the multicenter study. Conclusion: The MC simulations performed in this study indicate that the discrepancies recently found between PET/CT-measured activity and vendor-calibrated activity for 90Y glass and resin microspheres can be attributed to differences in the geometry of the respective commercial vials and to the metrologic approach adopted for activity meter calibration with a 90Y-chloride liquid source. Furthermore, IB photons were shown to play a relevant role in determining the electric current in the activity meter.
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Affiliation(s)
- Lucrezia Auditore
- Department of Biomedical and Dental Sciences and of Morphofunctional Imaging, University of Messina, Messina, Italy
- National Institute for Nuclear Physics, Catania, Italy
| | - Daniele Pistone
- Department of Biomedical and Dental Sciences and of Morphofunctional Imaging, University of Messina, Messina, Italy
- National Institute for Nuclear Physics, Catania, Italy
| | - Antonio Italiano
- National Institute for Nuclear Physics, Catania, Italy;
- Department of Mathematical and Computer Science, Physical Sciences, and Earth Sciences, University of Messina, Messina, Italy
| | - Ernesto Amato
- Department of Biomedical and Dental Sciences and of Morphofunctional Imaging, University of Messina, Messina, Italy;
- National Institute for Nuclear Physics, Catania, Italy
- Health Physics Unit, University Hospital "Gaetano Martino," Messina, Italy; and
| | - Silvano Gnesin
- Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
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Pistone D, Amato E, Auditore L, Baldari S, Italiano A. Updating 90Y Voxel S-Values including internal Bremsstrahlung: Monte Carlo study and development of an analytical model. Phys Med 2023; 112:102624. [PMID: 37354805 DOI: 10.1016/j.ejmp.2023.102624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 06/09/2023] [Accepted: 06/11/2023] [Indexed: 06/26/2023] Open
Abstract
PURPOSE Internal Bremsstrahlung (IB) is a process accompanying β-decay but neglected in Voxel S-Values (VSVs) calculation. Aims of this work were to calculate, through Monte Carlo (MC) simulation, updated 90Y-VSVs including IB, and to develop an analytical model to evaluate 90Y-VSVs for any voxel size of practical interest. METHODS GATE (Geant4 Application for Tomographic Emission) was employed for simulating voxelized geometries of soft tissue, with voxels sides l ranging from 2 to 6 mm, in steps of 0.5 mm. The central voxel was set as a homogeneous source of 90Y when IB photons are not modelled. For each l, the VSVs were computed for 90Y decays alone and for 90Y + IB. The analytical model was then built through fitting procedures of the VSVs including IB contribution. RESULTS Comparing GATE-VSVs with and without IB, differences between + 25% and + 30% were found for distances from the central voxel larger than the maximum β-range. The analytical model showed an agreement with MC simulations within ± 5% in the central voxel and in the Bremsstrahlung tails, for any l value examined, and relative differences lower than ± 40%, for other distances from the source. CONCLUSIONS The presented 90Y-VSVs include for the first time the contribution due to IB, thus providing a more accurate set of dosimetric factors for three-dimensional internal dosimetry of 90Y-labelled radiopharmaceuticals and medical devices. Furthermore, the analytical model constitutes an easy and fast alternative approach for 90Y-VSVs estimation for non-standard voxel dimensions.
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Affiliation(s)
- Daniele Pistone
- Department of Biomedical and Dental Sciences and of Morphologic and Functional Imaging (BIOMORF), University of Messina, Messina, Italy; INFN, National Institute for Nuclear Physics, Section of Catania, Catania, Italy
| | - Ernesto Amato
- Department of Biomedical and Dental Sciences and of Morphologic and Functional Imaging (BIOMORF), University of Messina, Messina, Italy; INFN, National Institute for Nuclear Physics, Section of Catania, Catania, Italy; Health Physics Unit, University Hospital "Gaetano Martino", Messina, Italy.
| | - Lucrezia Auditore
- Department of Biomedical and Dental Sciences and of Morphologic and Functional Imaging (BIOMORF), University of Messina, Messina, Italy; INFN, National Institute for Nuclear Physics, Section of Catania, Catania, Italy
| | - Sergio Baldari
- Department of Biomedical and Dental Sciences and of Morphologic and Functional Imaging (BIOMORF), University of Messina, Messina, Italy; Nuclear Medicine Unit, University Hospital "Gaetano Martino", Messina, Italy
| | - Antonio Italiano
- INFN, National Institute for Nuclear Physics, Section of Catania, Catania, Italy; Department of Mathematical and Computational Sciences, Physics Sciences and Earth Sciences (MIFT), University of Messina, Messina, Italy
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Italiano A, Pistone D, Amato E, Baldari S, Auditore L. Internal Bremsstrahlung, the missing process in beta decay Monte Carlo simulation: The relevance in 32P Dose-Point-Kernel estimation. Phys Med 2023; 110:102585. [PMID: 37119675 DOI: 10.1016/j.ejmp.2023.102585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 03/03/2023] [Accepted: 04/07/2023] [Indexed: 05/01/2023] Open
Abstract
PURPOSE In nuclear medicine, Dose Point Kernels (DPKs), representing the energy deposited all around a point isotropic source, are extensively used for dosimetry and are usually obtained by Monte Carlo (MC) simulations. For beta-decaying nuclides, DPK is usually estimated neglecting Internal Bremsstrahlung (IB) emission, a process always accompanying the beta decay and consisting in the emission of photons having a continuous spectral distribution. This work aims to study the significance of IB emission for DPK estimation in the case of 32P and provide DPK values corrected for the IB photon contribution. METHODS DPK, in terms of the scaled absorbed dose fraction, F(R/X90), was first estimated by GAMOS MC simulation using the standard beta decay spectrum of 32P, Fβ(R/X90). Subsequently, an additional source term accounting for IB photons and their spectral distribution was defined and used for a further MC simulation, thus evaluating the contribution of IB emission to DPK values, Fβ+IB(R/X90). The relative percent difference, δ, between the DPKs obtained by the two approaches, Fβ+IB vs. Fβ, was studied as a function of the radial distance, R. RESULTS As far as the energy deposition is mainly due to the beta particles, IB photons does not significantly contribute to DPK; conversely, for larger R, Fβ+IB values are higher by 30-40% than Fβ. CONCLUSIONS The inclusion of IB emission in the MC simulations for DPK estimations is recommended, as well as the use of the DPK values corrected for IB photons, here provided.
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Affiliation(s)
- Antonio Italiano
- INFN, National Institute for Nuclear Physics, Section of Catania, Italy; MIFT Department, University of Messina, Italy
| | - Daniele Pistone
- INFN, National Institute for Nuclear Physics, Section of Catania, Italy; Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Italy.
| | - Ernesto Amato
- INFN, National Institute for Nuclear Physics, Section of Catania, Italy; Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Italy; Health Physics Unit, University Hospital 'Gaetano Martino', Messina, Italy
| | - Sergio Baldari
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Italy; Nuclear Medicine Unit, University Hospital 'Gaetano Martino', Messina, Italy
| | - Lucrezia Auditore
- INFN, National Institute for Nuclear Physics, Section of Catania, Italy; Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Italy
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Auditore L, Amato E, Pistone D, Italiano A. Technical note: The contribution of internal bremsstrahlung to the 90 Y dose point kernel. Med Phys 2023; 50:1865-1870. [PMID: 36533673 DOI: 10.1002/mp.16171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 10/09/2022] [Accepted: 12/08/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Internal dosimetry has an increasing role in the planning and verification of nuclear medicine therapies with radiopharmaceuticals. Dose Point Kernels (DPKs), quantifying the energy deposition all around a point source, in a homogenous medium, are extensively used for 3D dosimetry and nowadays are mostly evaluated by Monte Carlo (MC) simulation. To our knowledge, DPK for beta emitters is estimated neglecting the continuous photon emission due to the Internal Bremsstrahlung (IB), whose contribution to the absorbed dose can be relevant beyond the maximum range of betas, as evidenced in recent works. PURPOSE Aim of this study was to investigate and quantify, by means of MC simulations, the contribution of IB photons to DPK calculated for 90 Y and provide the updated 90 Y DPK. METHODS The overall radiation due to the decay of a 90 Y point source, placed at the centre of concentric water shells of increasing radii from 0.02 cm to 20 cm, was simulated with GAMOS, including the IB source term whose spectral distribution was described by an analytical model. Energy deposition was scored in the shells as a function of the distance from the source, R, and DPK was estimated in terms of the scaled absorbed dose fraction, F(R/X90 ), where X90 is the range within which the beta particles deposit 90% of their energy. RESULTS A comparison between the two simulated absorbed dose distributions, calculated with or without IB, clearly shows that the latter (incomplete) choice is consistent with the findings of other Authors and systematically underestimates the absorbed dose imparted to the tissue. 90 Y DPK values currently used are underestimated by 20%-34% for R>2X90 . CONCLUSIONS The revised values provided in this work suggest that the inclusion of IB emission in DPK evaluations is advisable for pure beta emitters.
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Affiliation(s)
- Lucrezia Auditore
- Department of Biomedical and Dental Sciences and of Morphologic and Functional Imaging (BIOMORF), University of Messina, Italy
- INFN, National Institute for Nuclear Physics, Section of Catania, Italy
| | - Ernesto Amato
- Department of Biomedical and Dental Sciences and of Morphologic and Functional Imaging (BIOMORF), University of Messina, Italy
- INFN, National Institute for Nuclear Physics, Section of Catania, Italy
| | - Daniele Pistone
- Department of Biomedical and Dental Sciences and of Morphologic and Functional Imaging (BIOMORF), University of Messina, Italy
- INFN, National Institute for Nuclear Physics, Section of Catania, Italy
| | - Antonio Italiano
- INFN, National Institute for Nuclear Physics, Section of Catania, Italy
- Department of Mathematical and Computer Science, Physical Sciences and Earth Sciences (MIFT), University of Messina, Italy
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Auditore L, Juget F, Pistone D, Nedjadi Y, Amato E, Italiano A. Internal Bremsstrahlung emission during 32P decay. RADIAT MEAS 2022. [DOI: 10.1016/j.radmeas.2022.106799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Auditore L, Pistone D, Amato E, Italiano A. Monte Carlo methods in nuclear medicine. Nucl Med Mol Imaging 2022. [DOI: 10.1016/b978-0-12-822960-6.00136-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Auditore L, Juget F, Italiano A, Pistone D, Nedjadi Y, Gnesin S, Amato E. Relevance of Internal Bremsstrahlung photons from 90Y decay: an experimental and Monte Carlo study. Phys Med 2021; 90:158-163. [PMID: 34662819 DOI: 10.1016/j.ejmp.2021.10.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 10/05/2021] [Accepted: 10/05/2021] [Indexed: 11/27/2022] Open
Abstract
Internal Bremsstrahlung (IB) is a continuous electromagnetic radiation accompanying beta decay; however, this process is not considered in radiation protection studies, particularly when estimating exposure from beta-decaying radionuclides. The aims of the present work are: i) to show that neglecting the IB process in Monte Carlo (MC) simulation leads to an underestimation of the energy deposited in a ionization chamber, in the case of a high-energy pure beta emitter such as Yttrium-90 (90Y), and ii) to determine the most reliable choice of source term for 90Y IB to be used in MC simulations. For this radionuclide, commonly employed in nuclear medicine and radiochemistry applications, experimental data acquired with a well ionization chamber have been compared with Monte Carlo (MC) calculations carried out in the GAMOS framework. Simulations that do not include the effect of the IB process, are found to give results underestimating the experimental values by 12-14%. Consequently, two models for the IB energy spectra, previously described by Italiano et al. [1], have been implemented using MC simulation and a good agreement has been achieved with one of them. We therefore conclude that inclusion of IB process in Monte Carlo simulation packages is advisable for a more accurate and complete treatment of electromagnetic interactions.
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Affiliation(s)
- Lucrezia Auditore
- Section of Radiological Sciences, Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Italy; INFN, National Institute for Nuclear Physics, Section of Catania, Italy
| | - Frederic Juget
- Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Antonio Italiano
- INFN, National Institute for Nuclear Physics, Section of Catania, Italy; MIFT Department, University of Messina, Italy.
| | - Daniele Pistone
- INFN, National Institute for Nuclear Physics, Section of Catania, Italy; MIFT Department, University of Messina, Italy
| | - Youcef Nedjadi
- Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Silvano Gnesin
- Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Ernesto Amato
- Section of Radiological Sciences, Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Italy; INFN, National Institute for Nuclear Physics, Section of Catania, Italy
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