Assessment of scintigraphic imaging with Terbium-161: A visual and quantitative analysis

The Auger emitter ¹⁶¹Tb is an increasingly discussed radionuclide for targeted radionuclide therapy. The aim of this study was to assess the feasibility of scintigraphic imaging with ¹⁶¹Tb in terms of image quality and quantitative capabilities by phantom measurements and to evaluate the suitability of this radionuclide for clinical use. Phantom measurements were conducted using a standardized NEMA IEC body phantom filled with activity concentrations ranging from 2.5 GBq to 100 MBq. Both visual and quantitative analyses were performed, including assessment of the image calibration factor (CF), as well as the recovery coefficient (RC) and the contrast-to-noise ratio (CNR) of the individual spheres. The results observed in this study demonstrate that quantitative SPECT/CT imaging with ¹⁶¹Tb is feasible over a wide range of activity making this radionuclide suitable for clinical applications. Acquiring a total of at least 5 million photopeak counts enables visual detectability of lesions of diameter lower than 20 mm and quantitative calibration for dosimetry purposes.