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Bergeron DE, Cessna JT, Broder BA, Pibida L, Fitzgerald RP, DiGiorgio M, Napoli E, Zimmerman BE. Activity standard and calibrations for 227Th with ingrowing progeny. Appl Radiat Isot 2024; 209:111326. [PMID: 38701595 DOI: 10.1016/j.apradiso.2024.111326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 03/10/2024] [Accepted: 04/10/2024] [Indexed: 05/05/2024]
Abstract
Thorium-227 was separated from its progeny and standardized for activity by the triple-to-double coincidence ratio (TDCR) method of liquid scintillation counting. Confirmatory liquid scintillation-based measurements were made using efficiency tracing with 3H and live-timed anticoincidence counting (LTAC). The separation time and the efficiency of the separation were confirmed by gamma-ray spectrometry. Calibrations for reentrant pressurized ionization chambers, including commercial radionuclide calibrators, and a well-type NaI(Tl) detector are discussed.
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Affiliation(s)
- Denis E Bergeron
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
| | - Jeffrey T Cessna
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Brittany A Broder
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Leticia Pibida
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Ryan P Fitzgerald
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Morgan DiGiorgio
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | | | - Brian E Zimmerman
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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Fung EK, Zanzonico PB. Monitoring the biodistribution of radiolabeled therapeutics in mice. Methods Cell Biol 2023; 180:93-111. [PMID: 37890935 DOI: 10.1016/bs.mcb.2023.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/29/2023]
Abstract
Radiopharmaceutical therapy is a rapidly growing field for the treatment of cancer due to its high specificity and ability to target individual affected cells. A key component of the pre-clinical development of a new therapeutic radiopharmaceutical is the determination of its time-dependent distribution in tumors, normal tissues, and the whole body in mouse tumor models. Here, we provide an overview of the available instrumentation for the novice in radiation measurement. We also detail the methodology for assessing distribution and kinetics of a radiopharmaceutical and calculating radiation absorbed dose in mice using a gamma counter or a PET or SPECT camera.
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Affiliation(s)
- Edward K Fung
- Department of Radiology, Weill Cornell Medicine, New York, NY, United States.
| | - Pat B Zanzonico
- Department of Medical Physics, Memorial Sloan Kettering Medical Center, New York, NY, United States
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Castillo Seoane D, De Saint-Hubert M, Ahenkorah S, Saldarriaga Vargas C, Ooms M, Struelens L, Koole M. Gamma counting protocols for the accurate quantification of 225Ac and 213Bi without the need for a secular equilibrium between parent and gamma-emitting daughter. EJNMMI Radiopharm Chem 2022; 7:28. [PMID: 36274098 PMCID: PMC9588853 DOI: 10.1186/s41181-022-00174-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 08/22/2022] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Quantification of actinium-225 through gamma counter measurements, when there is no secular equilibrium between actinium-225 and its gamma emitting daughters bismuth-213 and/or francium-221, can provide valuable information regarding the possible relocation of recoiled daughters such that related radiotoxicity effects can be evaluated. This study proposes a multiple time-point protocol using the bismuth-213 photopeak with measurements before secular equilibrium between actinium-225 and bismuth-213, and a single time-point protocol using both the francium-221 and bismuth-213 photopeak while assuming secular equilibrium between actinium-225 and francium-221 but not between bismuth-213 and actinium-225. RESULTS Good agreement (i.e. 3% accuracy) was obtained when relying on a multiple time-points measurement of bismuth-213 to quantify both actinium-225 and excess of bismuth-213. Following scatter correction, actinium-225 can be accurately quantified using the francium-221 in a single time-point measurement within 3% of accuracy. The analysis performed on the stability data of [225Ac]Ac-DEPA and [225Ac]Ac-DOTA complexes, before secular equilibrium between bismuth-213 and actinium-225 was formed, revealed considerable amounts of unbound bismuth-213 (i.e. more than 90%) after 24 h of the radiolabeling most likely due to the recoiled daughter effect. CONCLUSION Both protocols were able to accurately estimate 225Ac-activities provided the francium-221 energy window was corrected for the down scatter of the higher-energy gamma-emissions by bismuth-213. This could prove beneficial to study the recoiled daughter effect and redistribution of free bismuth-213 by monitoring the accumulation or clearance of bismuth-213 in different tissues during biodistribution studies or in patient samples during clinical studies. On the other hand, the single gamma counter measurement protocol, although required a 30 min waiting time, is more time and cost efficient and therefore more appropriate for standardized quality control procedures of 225Ac-labeled radiopharmaceuticals.
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Affiliation(s)
- Dayana Castillo Seoane
- Unit of Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, Katholieke Universiteit Leuven (KUL), Louvain, Belgium.
- Research Unit in Dosimetric Applications, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium.
| | - Marijke De Saint-Hubert
- Research Unit in Dosimetric Applications, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Stephen Ahenkorah
- NURA Research Group, Belgian Nuclear Research Center (SCK CEN), Mol, Belgium
- Unit of Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, Katholieke Universiteit Leuven (KUL), Louvain, Belgium
| | - Clarita Saldarriaga Vargas
- Research Unit in Dosimetric Applications, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
- Department of Medical Imaging, Laboratory for In Vivo Cellular and Molecular Imaging, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Maarten Ooms
- NURA Research Group, Belgian Nuclear Research Center (SCK CEN), Mol, Belgium
| | - Lara Struelens
- Research Unit in Dosimetric Applications, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Michel Koole
- Unit of Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, Katholieke Universiteit Leuven (KUL), Louvain, Belgium
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Espagnet R, Frezza A, Martin JP, Hamel LA, Lechippey L, Beauregard JM, Després P. A CZT-based blood counter for quantitative molecular imaging. EJNMMI Phys 2017; 4:18. [PMID: 28577291 PMCID: PMC5457380 DOI: 10.1186/s40658-017-0184-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 05/02/2017] [Indexed: 11/30/2022] Open
Abstract
Background Robust quantitative analysis in positron emission tomography (PET) and in single-photon emission computed tomography (SPECT) typically requires the time-activity curve as an input function for the pharmacokinetic modeling of tracer uptake. For this purpose, a new automated tool for the determination of blood activity as a function of time is presented. The device, compact enough to be used on the patient bed, relies on a peristaltic pump for continuous blood withdrawal at user-defined rates. Gamma detection is based on a 20 × 20 × 15 mm3 cadmium zinc telluride (CZT) detector, read by custom-made electronics and a field-programmable gate array-based signal processing unit. A graphical user interface (GUI) allows users to select parameters and easily perform acquisitions. Results This paper presents the overall design of the device as well as the results related to the detector performance in terms of stability, sensitivity and energy resolution. Results from a patient study are also reported. The device achieved a sensitivity of 7.1 cps/(kBq/mL) and a minimum detectable activity of 2.5 kBq/ml for 18F. The gamma counter also demonstrated an excellent stability with a deviation in count rates inferior to 0.05% over 6 h. An energy resolution of 8% was achieved at 662 keV. Conclusions The patient study was conclusive and demonstrated that the compact gamma blood counter developed has the sensitivity and the stability required to conduct quantitative molecular imaging studies in PET and SPECT.
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Affiliation(s)
- Romain Espagnet
- Department of Physics, Engineering Physics and Optics and Cancer Research Center, Université Laval, Quebec City, G1V 0A6, QC, Canada
| | - Andrea Frezza
- Department of Physics, Engineering Physics and Optics and Cancer Research Center, Université Laval, Quebec City, G1V 0A6, QC, Canada
| | - Jean-Pierre Martin
- Department of Physics, Université de Montréal, C.P. 6128, Montréal, H3C 3J7, QC, Canada
| | - Louis-André Hamel
- Department of Physics, Université de Montréal, C.P. 6128, Montréal, H3C 3J7, QC, Canada
| | - Laëtitia Lechippey
- Department of Physics, Engineering Physics and Optics and Cancer Research Center, Université Laval, Quebec City, G1V 0A6, QC, Canada
| | - Jean-Mathieu Beauregard
- Department of Medical Imaging and Research Center of CHU de Québec - Université Laval, Quebec City, G1R 2J6, QC, Canada.,Department of Radiology and Nuclear medicine and Cancer Research Center, Université Laval, Quebec CityQC, G1V 0A6, Canada
| | - Philippe Després
- Department of Physics, Engineering Physics and Optics and Cancer Research Center, Université Laval, Quebec City, G1V 0A6, QC, Canada. .,Department of Radiation Oncology and Research Center of CHU de Québec - Université Laval, Quebec City, G1R 2J6, QC, Canada.
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Lodge MA, Holt DP, Kinahan PE, Wong DF, Wahl RL. Performance assessment of a NaI(Tl) gamma counter for PET applications with methods for improved quantitative accuracy and greater standardization. EJNMMI Phys 2015; 2. [PMID: 26046011 PMCID: PMC4452125 DOI: 10.1186/s40658-015-0114-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Background Although NaI(Tl) gamma counters play an important role in many quantitative positron emission tomography (PET) protocols, their calibration for positron-emitting samples has not been standardized across imaging sites. In this study, we characterized the operational range of a gamma counter specifically for positron-emitting radionuclides, and we assessed the role of traceable 68Ge/68Ga sources for standardizing system calibration. Methods A NaI(Tl) gamma counter was characterized with respect to count rate performance, adequacy of detector shielding, system stability, and sample volume effects using positron-emitting radionuclides (409- to 613-keV energy window). System efficiency was measured using 18F and compared with corresponding data obtained using a long-lived 68Ge/68Ga source that was implicitly traceable to a national standard. Results One percent count loss was measured at 450 × 103 counts per minute. Penetration of the detector shielding by 511-keV photons gave rise to a negligible background count rate. System stability tests showed a coefficient of variation of 0.13% over 100 days. For a sample volume of 4 mL, the efficiencies relative to those at 0.1 mL were 0.96, 0.94, 0.91, 0.78, and 0.72 for 11C, 18F, 125I, 99mTc, and 51Cr, respectively. The efficiency of a traceable 68Ge/68Ga source was 30.1% ± 0.07% and was found to be in close agreement with the efficiency for 18F after consideration of the different positron fractions. Conclusions Long-lived 68Ge/68Ga reference sources, implicitly traceable to a national metrology institute, can aid standardization of gamma counter calibration for 18F. A characteristic feature of positron emitters meant that accurate calibration could be maintained over a wide range of sample volumes by using a narrow energy window centered on the 511-keV peak.
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Affiliation(s)
- Martin A Lodge
- Division of Nuclear Medicine, The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Daniel P Holt
- Division of Nuclear Medicine, The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Paul E Kinahan
- Department of Radiology, University of Washington, Seattle, WA, USA
| | - Dean F Wong
- Division of Nuclear Medicine, The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Richard L Wahl
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, USA
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