arXiv subjects

Anzhelika N. Moiseeva

Publications and source records attributed to Anzhelika N. Moiseeva.

2 recordsLinked to original sources

arXiv2026

Quantitative Imaging of Scandium Isotopes with a Long Axial Field-of-View PET/CT

Objective. $^{43}$Sc and $^{44}$Sc are positron-emitting isotopes of scandium that have attracted growing interest for theranostic applications in conjunction with the therapeutic isotope $^{47}$Sc. Both isotopes are non-pure positron emitters, and the associated prompt-gamma emission together with the high positron energy introduce complexities in achieving precise quantitative imaging. Approach. We evaluated the quantitative imaging performance of $^{44}$Sc and a $^{43/44}$Sc mixture on a long axial field-of-view (LAFOV) PET/CT using a NEMA IEC body phantom. We assessed contrast recovery coefficients, image noise and bias for different numbers of iterations and for absolute versus relative scatter correction, and implemented an isotope-specific point-spread-function (PSF) correction based on FLUKA-simulated positron ranges. Main results. The quantitative imaging performance of both isotopes is comparable to $^{18}$F, and the vendor's prompt-gamma correction effectively suppresses the additional random coincidences and lung error caused by prompt-gamma emission. The isotope-specific PSF correction further improves contrast recovery. While the bias obtained for $^{44}$Sc meets the EARL acceptance criterion for non-standard radionuclides, the bias for the $^{43/44}$Sc mixture exceeds it, which we attribute to the mixture-specific cross-calibration of the dose calibrators rather than to the PET imaging. Significance. Our results support the use of LAFOV PET/CT for quantitative imaging of scandium isotopes and provide practical reconstruction recommendations for clinical protocols.

physics.med-ph↗

arXiv2026

Terbium-149 PET/CT: First Quantitative Imaging with a Clinical Long-Axial Field-of-View Scanner

Introduction: Terbium-149 ($^{149}$Tb) is a promising radionuclide for targeted $α$ therapy that has a non-zero branching ratio (BR) for positron decay. However, its relatively low positron branching fraction and multiple prompt $γ$ emissions may challenge quantitative imaging. This study evaluates, for the first time, the imaging performance and quantitative accuracy of $^{149}$Tb using a clinical long axial field-of-view (LAFOV) PET/CT system. Methods: Quantitative accuracy of $^{149}$Tb was assessed with a NEMA IEC body phantom, which was filled with about 45 MBq $^{149}$Tb and a sphere-to-background ration of 10:1. The phantom was scanned for 20 min and shorter scan times and lower activities were simulated. Recovery coefficients, coefficient of variation, and lung residual error were evaluated for different reconstruction settings and compared to the EARL standard 2 for $^{18}$F. Results: High-quality PET images of $^{149}$Tb were obtained, even with a simulated total activity of 4.5 MBq. The 20 min and full activity scan yielded a mean recovery coefficient $RC_\textit{mean}$ of $0.55$, $0.69$, $0.73$, $0.76$, $0.79$, and $0.81$ for the six phantom spheres. Despite the low count statistics, the coefficient of variation stays mostly below $15\,\%$. Relative scatter correction combined with prompt $γ$ modeling provided robust quantification. Conclusion: $^{149}$Tb can be imaged using a commercial LAFOV PET/CT with a quantitative accuracy comparable to the EARL standard 2 for $^{18}$F. These findings demonstrate the feasibility of PET-based treatment verification and dosimetry for targeted $α$ therapy with $^{149}$Tb.

physics.med-ph↗