dc.date.accessioned | 2024-03-18T18:04:49Z | |
dc.date.available | 2024-03-18T18:04:49Z | |
dc.date.created | 2023-09-05T10:34:03Z | |
dc.date.issued | 2023 | |
dc.identifier.citation | Mikalsen, Lars Tore Gyland Kvassheim, Monika Stokke, Caroline . Optimized SPECT Imaging of 224Ra α-Particle Therapy by 212Pb Photon Emissions. Journal of Nuclear Medicine. 2023, 64(7), 1131-1137 | |
dc.identifier.uri | http://hdl.handle.net/10852/109779 | |
dc.description.abstract | In preparation for an α-particle therapy trial using 1–7 MBq of 224Ra, the feasibility of tomographic SPECT/CT imaging was of interest. The nuclide decays in 6 steps to stable 208Pb, with 212Pb as the principle photon-emitting nuclide. 212Bi and 208Tl emit high-energy photons up to 2,615 keV. A phantom study was conducted to determine the optimal acquisition and reconstruction protocol. Methods: The spheres of a body phantom were filled with a 224Ra-RaCl2 solution, and the background compartment was filled with water. Images were acquired on a SPECT/CT system. In addition, 30-min scans were acquired for 80- and 240-keV emissions, using triple-energy windows, with both medium-energy and high-energy collimators. Images were acquired at 90–95 and 29–30 kBq/mL, plus an explorative 3-min acquisition at 20 kBq/mL (using only the optimal protocol). Reconstructions were performed with attenuation correction only, attenuation plus scatter correction, 3 levels of postfiltering, and 24 levels of iterative updates. Acquisitions and reconstructions were compared using the maximum value and signal-to-scatter peak ratio for each sphere. Monte Carlo simulations were performed to examine the contributions of key emissions. Results: Secondary photons of the 2,615-keV 208Tl emission produced in the collimators make up most of the acquired energy spectrum, as revealed by Monte Carlo simulations, with only a small fraction (3%–6%) of photons in each window providing useful information for imaging. Still, decent image quality is possible at 30 kBq/mL, and nuclide concentrations are imageable down to approximately 2–5 kBq/mL. The overall best results were obtained with the 240-keV window, medium-energy collimator, attenuation and scatter correction, 30 iterations and 2 subsets, and a 12-mm gaussian postprocessing filter. However, all combinations of the applied collimators and energy windows were capable of producing adequate results, even though some failed to reconstruct the 2 smallest spheres. Conclusion: SPECT/CT imaging of 224Ra in equilibrium with daughters is possible, with sufficient image quality to provide clinical utility for the current trial of intraperitoneally administrated activity. A systematic scheme for optimization was designed to select acquisition and reconstruction settings. | |
dc.language | EN | |
dc.rights | Attribution 4.0 International | |
dc.rights.uri | https://creativecommons.org/licenses/by/4.0/ | |
dc.title | Optimized SPECT Imaging of 224Ra α-Particle Therapy by 212Pb Photon Emissions | |
dc.title.alternative | ENEngelskEnglishOptimized SPECT Imaging of 224Ra α-Particle Therapy by 212Pb Photon Emissions | |
dc.type | Journal article | |
dc.creator.author | Mikalsen, Lars Tore Gyland | |
dc.creator.author | Kvassheim, Monika | |
dc.creator.author | Stokke, Caroline | |
cristin.unitcode | 185,53,63,0 | |
cristin.unitname | Klinikk for radiologi og nukleærmedisin | |
cristin.ispublished | true | |
cristin.fulltext | original | |
cristin.qualitycode | 2 | |
dc.identifier.cristin | 2172410 | |
dc.identifier.bibliographiccitation | info:ofi/fmt:kev:mtx:ctx&ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=Journal of Nuclear Medicine&rft.volume=64&rft.spage=1131&rft.date=2023 | |
dc.identifier.jtitle | Journal of Nuclear Medicine | |
dc.identifier.volume | 64 | |
dc.identifier.issue | 7 | |
dc.identifier.startpage | 1131 | |
dc.identifier.endpage | 1137 | |
dc.identifier.doi | https://doi.org/10.2967/jnumed.122.264455 | |
dc.type.document | Tidsskriftartikkel | |
dc.type.peerreviewed | Peer reviewed | |
dc.source.issn | 0161-5505 | |
dc.type.version | PublishedVersion | |