Comparison of ¹¹¹In Human Dosimetry Estimates Derived from Preclinical SPECT Imaging and Gamma Counting

Evaluating longitudinal SPECT imaging as an alternative approach to preclinical dosimetry and human absorbed dose estimation.

Accurate absorbed dose estimation is critical to radiopharmaceutical development, helping researchers understand tissue exposure and inform clinical translation. While ex vivo gamma counting remains the gold standard for preclinical biodistribution assessment, longitudinal SPECT imaging offers an alternative approach that enables repeated measurements within individual animals.

In this study, researchers from Perceptive Discovery and Barts Cancer Institute at Queen Mary University of London compared human absorbed dose estimates derived from ¹¹¹In-labeled Dinutuximab-Beta using longitudinal SPECT/CT imaging and ex vivo gamma counting. The findings demonstrated strong correlation between the two approaches, while highlighting important differences in lung dose estimates and the need to account for slow antibody clearance.

The results support the potential of longitudinal SPECT imaging as a valuable tool for estimating absorbed doses to dose-limiting organs, helping researchers refine preclinical dosimetry strategies and generate evidence to guide radiopharmaceutical development.

What You’ll Learn:

• Comparing dosimetry approaches: How longitudinal ¹¹¹In SPECT imaging compares with ex vivo gamma counting for estimating human absorbed doses.
• Understanding organ-specific differences: Key findings in lung, heart and liver biodistribution, including factors influencing absorbed dose estimates.
• Informing clinical translation: How imaging-based dosimetry can support longitudinal assessment and guide study design for radiopharmaceutical development.