Journal article
Gamma camera imaging characteristics of 203/212 Pb as a theragnostic pair for targeted alpha therapy: a feasibility study
EJNMMI physics, Vol.12(1), 50
05/27/2025
DOI: 10.1186/s40658-025-00763-2
PMCID: PMC12106261
PMID: 40419836
Abstract
Background
203Pb and 212Pb show promise as theragnostic agents for targeted alpha therapy (TAT) because two chemically identical isotopes can be used for diagnostic imaging and treatment. In the 212Pb decay chain, in addition to alpha and beta particles, a large number of photons are emitted, those with an energy of 239 keV and the characteristic X-rays of 212Pb could be used for imaging. 203Pb decays by photon emission with an energy of 279 keV, which appears suitable for gamma camera imaging. The aim of this study was to investigate suitable imaging protocols and to characterize the scintigraphic imaging properties and their implications for the clinical feasibility as theragnostic isotopes.
Methods
Planar and SPECT/CT images were obtained with medium- and high-energy collimators on a Siemens Symbia Intevo 6 using a NEMA image quality phantom in various phantom setups and another body-shaped phantom with several inserts. Different energy windows were investigated and measurements were evaluated in terms of sensitivity, count rate performance, spatial resolution, contrast recovery, lesion detectability, and image quantification.
Results
Evaluation of image quality showed superior imaging characteristics for 203Pb compared to 212Pb regarding spatial resolution, contrast recovery, image noise, and quantification accuracy. Both medium- and high- energy collimators were suitable for 203Pb imaging, with the medium energy collimators showed slightly better imaging properties. Images obtained with the HE collimators in the 79 keV energy window showed the best visual image quality for 212Pb. Due to high-energy photon emissions from 212Pb daughter nuclides (e.g., 2.6 MeV from 208Tl), dead time related count losses occurred even at low activities (20% count loss at 20 MBq for MELP collimators).
Conclusions
According to our results and first-in-human imaging studies, SPECT/CT imaging with the 203/212Pb theragnostic pair is clinically feasible. 203Pb is an appropriate imaging surrogate to investigate pharmacokinetics and perform predictive dosimetry. The less favorable imaging characteristics of 212Pb make image quantification and post-treatment dosimetry challenging and require further research.
Details
- Title: Subtitle
- Gamma camera imaging characteristics of 203/212 Pb as a theragnostic pair for targeted alpha therapy: a feasibility study
- Creators
- David Kästner - University Hospital Carl Gustav CarusHolger Hartmann - University Hospital Carl Gustav CarusRobert Freudenberg - University Hospital Carl Gustav CarusMarc Pretze - University Hospital Carl Gustav CarusClaudia Brogsitter - University Hospital Carl Gustav CarusMichael K Schultz - Perspective Therapeutics Inc, Coralville, IA, USAJörg Kotzerke - University Hospital Carl Gustav CarusEnrico Michler - University Hospital Carl Gustav Carus
- Resource Type
- Journal article
- Publication Details
- EJNMMI physics, Vol.12(1), 50
- DOI
- 10.1186/s40658-025-00763-2
- PMID
- 40419836
- PMCID
- PMC12106261
- NLM abbreviation
- EJNMMI Phys
- ISSN
- 2197-7364
- eISSN
- 2197-7364
- Publisher
- Springer
- Grant note
- Technische Universitt Dresden (1019)
The 212Pb isotope generator and the 203Pb used in this study were provided by Perspective Therapeutics, Inc.
- Language
- English
- Date published
- 05/27/2025
- Academic Unit
- Radiology; Radiation Oncology
- Record Identifier
- 9984824173102771
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