Reliable (accurate and precise) quantification of dose requires reliable absolute quantification of regional activity uptake. This is especially challenging for alpha-particle emitting radiopharmaceutical therapies due to the complex emission spectra, the very low number of detected counts, the impact of stray-radiation-related noise at these low counts, and other image-degrading processes such as attenuation, scatter, and collimator-detector response. To address these challenges, we are developing ultra-low-count quantitative SPECT methods that  directly estimates the regional activity uptake from the projection data, obviating the reconstruction step. This makes the problem more well-posed and avoids reconstruction-related information loss. These methods compensate for radioisotope and SPECT physics, including the isotope spectra, scatter, attenuation, and collimator-detector response, using Monte Carlo-based approaches. Our results based on validations with physical phantoms and virtual imaging trials are showing the accurate performance of these methods, as detailed in the references and the presentations below.




  • Z. Li, N. Benabdallah, D. Abou, B. Baumann, R. Wahl, D. Thorek, A. K. Jha, “A projection domain low-count quantitative SPECT method for alpha-particle emitting radiopharmaceutical therapy”, IEEE Trans. Rad. Plasma Med. Sci.,  2022 (Press release)
  • Z. Li, N. Benabdallah, D. Thorek, A. K. Jha, “A multiple-energy-window projection-domain quantitative SPECT method for joint regional uptake quantification of Th-227 and Ra-223”, Proceedings of the International Conference on Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine, 2021 (Oral Award Nominee
  • N Benabdallah, W Scheve, N Dunn, D Silvestros, P Schelker, R Laforest, R F Hobbs, Z Li, N M Maughan, U Jammalamadaka, J Michalski, B C Baumann, B Rogers, H Gay, D Abou, A Iravani, K. Jha, F. Dehdashti, D. L. J. Thorek, “Practical considerations for quantitative clinical SPECT/CT imaging of alpha particle emitting radioisotopes”, Theranostics
  • Z. Li, N. Benabdallah, D. Abou, B. Baumann, R. Wahl, D. Thorek, A. K. Jha, “A projection-domain quantification method for absolute quantification with low-count SPECT for alpha-particle radiopharmaceutical therapy”, Journal of Nuclear Medicine May 2021, 62 (supplement 1) 1539 (Best poster award nominee)
  • D. S. Abou, A. Rittenbach, R. E. Tomlinson, P. A. Finley, B. Tsui, B. W. Simons, A. K. Jha, D. Ulmert, R. C. Riddle, and D. L.J. Thorek, “Preclinical Single Photon Emission Computed Tomography of Alpha Particle-Emitting Radium-223”, Cancer Biotherapy & Radiopharmaceuticals, 35(7), pp. 520-529, 2020