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Fitzgerald R. Monte Carlo based approach to the LS–NaI 4πβ–γ anticoincidence extrapolation and uncertainty. Appl Radiat Isot 2016; 109:308-13. [PMID: 27358944 PMCID: PMC5068577 DOI: 10.1016/j.apradiso.2015.11.107] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The 4πβ–γ anticoincidence method is used for the primary standardization of β−, β+, electron capture (EC), α, and mixed-mode radionuclides. Efficiency extrapolation using one or more γ ray coincidence gates is typically carried out by a low-order polynomial fit. The approach presented here is to use a Geant4-based Monte Carlo simulation of the detector system to analyze the efficiency extrapolation. New code was developed to account for detector resolution, direct γ ray interaction with the PMT, and implementation of experimental β-decay shape factors. The simulation was tuned to 57Co and 60Co data, then tested with 99mTc data, and used in measurements of 18F, 129I, and 124I. The analysis method described here offers a more realistic activity value and uncertainty than those indicated from a least-squares fit alone.
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Affiliation(s)
- R. Fitzgerald
- National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899 USA
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5
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Bergeron DE, Cessna JT, Coursey BM, Fitzgerald R, Zimmerman BE. A Review of NIST Primary Activity Standards for (18)F: 1982 to 2013. JOURNAL OF RESEARCH OF THE NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY 2014; 119:371-96. [PMID: 26601035 PMCID: PMC4487292 DOI: 10.6028/jres.119.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 07/30/2014] [Indexed: 06/05/2023]
Abstract
The new NIST activity standardization for (18)F, described in 2014 in Applied Radiation and Isotopes (v. 85, p. 77), differs from results obtained between 1998 and 2008 by 4 %. The new results are considered to be very reliable; they are based on a battery of robust primary measurement techniques and bring the NIST standard into accord with other national metrology institutes. This paper reviews all ten (18)F activity standardizations performed at NIST from 1982 to 2013, with a focus on experimental variables that might account for discrepancies. We have identified many possible sources of measurement bias and eliminated most of them, but we have not adequately accounted for the 1998-2008 results.
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Affiliation(s)
- Denis E Bergeron
- National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Jeffrey T Cessna
- National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Bert M Coursey
- National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Ryan Fitzgerald
- National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Brian E Zimmerman
- National Institute of Standards and Technology, Gaithersburg, MD 20899
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7
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da Silva CJ, de Oliveira EM, Iwahara A, Delgado JU, Poledna R, de Oliveira AE, Moreira DS, da Silva RL, Gomes RDS, de Veras EV. Calibration of ionization chamber for ¹⁸F and ⁶⁸Ga. Appl Radiat Isot 2014; 87:188-91. [PMID: 24361323 DOI: 10.1016/j.apradiso.2013.11.137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 11/23/2013] [Indexed: 11/25/2022]
Abstract
In order to maintain the results of primary activity standardizations carried out in 2011 the LNMRI has determined the calibration factors for a pressurized 4π-ionization chamber for the nuclides (18)F and (68)Ga. This ionization chamber is coupled to a 6517A Keithley electrometer which is controlled by a homemade LabVIEW program. This paper will describe the main issues related to the calibration of an ionization chamber system for positron emitters and short half-life radionuclides such as timing, current measurement, background, decay, and (226)Ra check source measurements.
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Affiliation(s)
- Carlos J da Silva
- Laboratório Nacional de Metrologia das Radiações Ionizantes (LNMRI), Instituto de Radioproteção e Dosimetria (IRD), Comissão Nacional de Energia Nuclear (CNEN), Av. Salvador Allende, s/no-Barra da Tijuca, CEP 22783-127, Rio de Janeiro, Brazil.
| | - Estela M de Oliveira
- Laboratório Nacional de Metrologia das Radiações Ionizantes (LNMRI), Instituto de Radioproteção e Dosimetria (IRD), Comissão Nacional de Energia Nuclear (CNEN), Av. Salvador Allende, s/no-Barra da Tijuca, CEP 22783-127, Rio de Janeiro, Brazil
| | - A Iwahara
- Laboratório Nacional de Metrologia das Radiações Ionizantes (LNMRI), Instituto de Radioproteção e Dosimetria (IRD), Comissão Nacional de Energia Nuclear (CNEN), Av. Salvador Allende, s/no-Barra da Tijuca, CEP 22783-127, Rio de Janeiro, Brazil
| | - José U Delgado
- Laboratório Nacional de Metrologia das Radiações Ionizantes (LNMRI), Instituto de Radioproteção e Dosimetria (IRD), Comissão Nacional de Energia Nuclear (CNEN), Av. Salvador Allende, s/no-Barra da Tijuca, CEP 22783-127, Rio de Janeiro, Brazil
| | - R Poledna
- Laboratório Nacional de Metrologia das Radiações Ionizantes (LNMRI), Instituto de Radioproteção e Dosimetria (IRD), Comissão Nacional de Energia Nuclear (CNEN), Av. Salvador Allende, s/no-Barra da Tijuca, CEP 22783-127, Rio de Janeiro, Brazil
| | - Antônio E de Oliveira
- Laboratório Nacional de Metrologia das Radiações Ionizantes (LNMRI), Instituto de Radioproteção e Dosimetria (IRD), Comissão Nacional de Energia Nuclear (CNEN), Av. Salvador Allende, s/no-Barra da Tijuca, CEP 22783-127, Rio de Janeiro, Brazil
| | - Denise S Moreira
- Laboratório Nacional de Metrologia das Radiações Ionizantes (LNMRI), Instituto de Radioproteção e Dosimetria (IRD), Comissão Nacional de Energia Nuclear (CNEN), Av. Salvador Allende, s/no-Barra da Tijuca, CEP 22783-127, Rio de Janeiro, Brazil
| | - Ronaldo L da Silva
- Laboratório Nacional de Metrologia das Radiações Ionizantes (LNMRI), Instituto de Radioproteção e Dosimetria (IRD), Comissão Nacional de Energia Nuclear (CNEN), Av. Salvador Allende, s/no-Barra da Tijuca, CEP 22783-127, Rio de Janeiro, Brazil
| | - Regio dos Santos Gomes
- Laboratório Nacional de Metrologia das Radiações Ionizantes (LNMRI), Instituto de Radioproteção e Dosimetria (IRD), Comissão Nacional de Energia Nuclear (CNEN), Av. Salvador Allende, s/no-Barra da Tijuca, CEP 22783-127, Rio de Janeiro, Brazil
| | - Eduardo V de Veras
- Laboratório Nacional de Metrologia das Radiações Ionizantes (LNMRI), Instituto de Radioproteção e Dosimetria (IRD), Comissão Nacional de Energia Nuclear (CNEN), Av. Salvador Allende, s/no-Barra da Tijuca, CEP 22783-127, Rio de Janeiro, Brazil
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8
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Fitzgerald R, Zimmerman BE, Bergeron DE, Cessna JC, Pibida L, Moreira DS. A new NIST primary standardization of 18F. Appl Radiat Isot 2014; 85:77-84. [PMID: 24384397 DOI: 10.1016/j.apradiso.2013.11.116] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 11/26/2013] [Accepted: 11/27/2013] [Indexed: 11/15/2022]
Abstract
A new primary standardization of (18)F by NIST is reported. The standard is based on live-timed beta-gamma anticoincidence counting with confirmatory measurements by three other methods: (i) liquid scintillation (LS) counting using CIEMAT/NIST (3)H efficiency tracing; (ii) triple-to-double coincidence ratio (TDCR) counting; and (iii) NaI integral counting and HPGe γ-ray spectrometry. The results are reported as calibration factors for NIST-maintained ionization chambers (including some "dose calibrators"). The LS-based methods reveal evidence for cocktail instability for one LS cocktail. Using an ionization chamber to link this work with previous NIST results, the new value differs from the previous reports by about 4%, but appears to be in good agreement with the key comparison reference value (KCRV) of 2005.
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Affiliation(s)
- R Fitzgerald
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), 100 Bureau Drive, Gaithersburg, MD 20899, USA.
| | - B E Zimmerman
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), 100 Bureau Drive, Gaithersburg, MD 20899, USA
| | - D E Bergeron
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), 100 Bureau Drive, Gaithersburg, MD 20899, USA
| | - J C Cessna
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), 100 Bureau Drive, Gaithersburg, MD 20899, USA
| | - L Pibida
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), 100 Bureau Drive, Gaithersburg, MD 20899, USA
| | - D S Moreira
- Laboratório Nacional de Metrologia das Radiações Ionizantes, Comissão Nacional de Energia Nuclear, Avenida Salvador Allende, s/n, Recreio dos Bandeirantes, CEP 22783-127 Rio de Janeiro, RJ, Brazil
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9
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Sahagia M, Luca A, Antohe A, Ivan C. Standardization of 64Cu and 68Ga by the 4π(PC)β-γ coincidence method and calibration of the ionization chamber. Appl Radiat Isot 2012; 70:2025-30. [DOI: 10.1016/j.apradiso.2012.02.043] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 02/19/2012] [Indexed: 11/24/2022]
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Wurdiyanto G, Marsoem P, Candra H, Wijono P. Radioactivity measurement of 18F in 16ml vials for calibration of radionuclide calibrators. Appl Radiat Isot 2012; 70:2237-9. [DOI: 10.1016/j.apradiso.2012.02.111] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 02/22/2012] [Indexed: 10/28/2022]
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Hasegawa T, Sato Y, Oda K, Wada Y, Murayama H, Yamada T. Semi-quantitative and simulation analyses of effects of γ rays on determination of calibration factors of PET scanners with point-like22Na sources. Phys Med Biol 2011; 56:6031-45. [DOI: 10.1088/0031-9155/56/18/016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Nedjadi Y, Bailat C, Caffari Y, Bochud F. Standardisation of 18F by a coincidence method using full solid angle detectors. Appl Radiat Isot 2010; 68:1309-13; discussion 1313. [PMID: 20106673 DOI: 10.1016/j.apradiso.2010.01.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A solution of (18)F was standardised with a 4pibeta-4pigamma coincidence counting system in which the beta detector is a one-inch diameter cylindrical UPS89 plastic scintillator, positioned at the bottom of a well-type 5''x5'' NaI(Tl) gamma-ray detector. Almost full detection efficiency-which was varied downwards electronically-was achieved in the beta-channel. Aliquots of this (18)F solution were also measured using 4pigamma NaI(Tl) integral counting and Monte Carlo calculated efficiencies as well as the CIEMAT-NIST method. Secondary measurements of the same solution were also performed with an IG11 ionisation chamber whose equivalent activity is traceable to the Système International de Référence through the contribution IRA-METAS made to it in 2001; IRA's degree of equivalence was found to be close to the key comparison reference value (KCRV). The (18)F activity predicted by this coincidence system agrees closely with the ionisation chamber measurement and is compatible within one standard deviation of the other primary measurements. This work demonstrates that our new coincidence system can standardise short-lived radionuclides used in nuclear medicine.
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Affiliation(s)
- Youcef Nedjadi
- Institut de Radiophysique Appliquée, Lausanne, Switzerland.
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