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Updated: Jul 28, 2025
07:05
Correlative Optical Spectroscopy and Mass Spectrometry Imaging Methodology to Visualise Drug Distribution in a Soft Tissue Section
Published on: June 20, 2025
849
Optimized SPECT Imaging of
Lars Tore Gyland Mikalsen1,2, Monika Kvassheim3,4, Caroline Stokke3,5
1Division of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway; ltmikals@ous-hf.no.
Summary
This study demonstrates that SPECT/CT imaging is feasible for Radium-224 (224Ra) therapy, enabling visualization of therapeutic nuclide concentrations. Optimized protocols achieve sufficient image quality for clinical trials.
Area of Science:
- Nuclear Medicine
- Radiopharmaceutical Therapy Imaging
- Medical Physics
Background:
- Radium-224 (224Ra) is used in alpha-particle therapy, necessitating effective imaging for treatment monitoring.
- 224Ra decays through several daughter nuclides, emitting photons that complicate SPECT/CT imaging.
- Optimizing SPECT/CT protocols is crucial for visualizing 224Ra and its daughters in vivo.
Purpose of the Study:
- To determine the feasibility and optimal protocol for SPECT/CT imaging of 224Ra.
- To assess image quality and achievable nuclide concentration detection limits.
- To guide SPECT/CT acquisition and reconstruction for upcoming 224Ra therapy trials.
Main Methods:
- A phantom study using 224Ra-RaCl2 solution in a body phantom was conducted.
- SPECT/CT scans were acquired using various energy windows, collimators, and acquisition times.
- Image reconstruction involved attenuation and scatter correction, postfiltering, and iterative updates.
- Monte Carlo simulations were used to analyze photon contributions.
Main Results:
- Secondary photons from 208Tl (2,615 keV) dominate the energy spectrum, with only 3-6% useful photons.
- Decent image quality was achieved at 30 kBq/mL, with detection down to 2-5 kBq/mL.
- Optimal results used a 240-keV window, medium-energy collimator, scatter correction, 30 iterations, and a 12-mm Gaussian filter.
Conclusions:
- SPECT/CT imaging of 224Ra in equilibrium with its daughters is clinically viable.
- Sufficient image quality is achievable for monitoring intraperitoneally administered 224Ra activity.
- A systematic optimization scheme was developed for SPECT/CT acquisition and reconstruction settings.
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