Quantitative planar imaging of silver-111 (111Ag) is feasible and reliable when optimized scatter correction is combined with multi-photopeak acquisition, according to a phantom-based validation study published in EJNMMI Physics. The work evaluated the imaging performance of the radionuclide on a preclinical planar SPECT system, with a focus on accurate activity estimation.
The study was conducted using the γ-eye preclinical planar imaging system. Imaging was performed at the three principal gamma emissions of 111Ag, at 96.7, 245.4, and 342.1 keV. All three photopeaks were clearly detected, enabling multi-energy imaging of the isotope.
Calibration measurements used activity-filled vials to assess system linearity and sensitivity. The researchers observed a strong linear relationship between count rate and activity, with an R² value greater than 0.99, indicating that the system responds predictably across the measured activity range.
Scatter correction was carried out using the Triple-Energy Window (TEW) method. The team tested different window settings and found that optimized parameters — a main window of ± 15% and side windows of ± 10 keV — offered the best balance between sensitivity, signal-to-noise ratio, and quantification accuracy.
To evaluate quantitative accuracy under more realistic conditions, the researchers employed a mouse phantom with realistic activity distributions. Quantitative analysis of the phantom demonstrated good agreement between measured and reference activity values, suggesting that the imaging protocol can estimate activity reliably in a preclinical setting.
In addition to scatter correction, the study applied a multi-photopeak acquisition approach, summing data across the three gamma emissions to improve sensitivity. This summation increased sensitivity while maintaining quantification accuracy, according to the reported results.
The authors conclude that the proposed methodology enables accurate activity estimation and provides a robust framework for preclinical dosimetry.
The findings are limited to a phantom-based preclinical evaluation on a single planar imaging system; the study reports technical performance in phantoms and vials rather than results in living organisms or patients. The article was published as open access on 1 October 2026 and is shared as an accepted manuscript version that is subject to further edits before the final version of record.
Subject of Research: Phantom validation of quantitative preclinical planar imaging of silver-111
Article Title: Quantitative preclinical planar imaging of 111Ag: phantom validation
Article References: Leso, A., Stamatelatou, A., Lamprou, E., Fysikopoulos, E., Arzenton, A., Serafini, D., Mariotti, E., & Asti, M. (2026). Quantitative preclinical planar imaging of 111Ag: phantom validation. EJNMMI Physics. https://doi.org/10.1186/s40658-026-00906-z
Image Credits: AI Generated
DOI: 10.1186/s40658-026-00906-z
Keywords: silver-111, 111Ag, planar SPECT, preclinical imaging, scatter correction, triple-energy window, multi-photopeak acquisition, quantification, dosimetry, theranostics, phantom study, gamma imaging
News Source: Denise Maddox. (October 29, 2026). Phantom study shows silver-111 can be quantitatively imaged in preclinical planar SPECT. Scienmag.
