A list-mode multi-energy window low-count SPECT reconstruction method for isotopes with multiple emission peaks

Md Ashequr Rahman, Zekun Li, Zitong Yu, Richard Laforest, Daniel L.J. Thorek, Abhinav K. Jha

Research output: Contribution to journalArticlepeer-review


Background: Single-photon emission computed tomography (SPECT) provides a mechanism to perform absorbed-dose quantification tasks for α -particle radiopharmaceutical therapies (α -RPTs). However, quantitative SPECT for α -RPT is challenging due to the low number of detected counts, the complex emission spectrum, and other image-degrading artifacts. Towards addressing these challenges, we propose a low-count quantitative SPECT reconstruction method for isotopes with multiple emission peaks. Methods: Given the low-count setting, it is important that the reconstruction method extracts the maximal possible information from each detected photon. Processing data over multiple energy windows and in list-mode (LM) format provide mechanisms to achieve that objective. Towards this goal, we propose a list-mode multi energy window (LM-MEW) ordered-subsets expectation–maximization-based SPECT reconstruction method that uses data from multiple energy windows in LM format and include the energy attribute of each detected photon. For computational efficiency, we developed a multi-GPU-based implementation of this method. The method was evaluated using 2-D SPECT simulation studies in a single-scatter setting conducted in the context of imaging [223 Ra]RaCl 2 , an FDA-approved RPT for metastatic prostate cancer. Results: The proposed method yielded improved performance on the task of estimating activity uptake within known regions of interest in comparison to approaches that use a single energy window or use binned data. The improved performance was observed in terms of both accuracy and precision and for different sizes of the region of interest. Conclusions: Results of our studies show that the use of multiple energy windows and processing data in LM format with the proposed LM-MEW method led to improved quantification performance in low-count SPECT of isotopes with multiple emission peaks. These results motivate further development and validation of the LM-MEW method for such imaging applications, including for α -RPT SPECT.

Original languageEnglish
Article number40
JournalEJNMMI Physics
Issue number1
StatePublished - Dec 2023


  • List-mode data
  • Objective task-based evaluation
  • Quantitative SPECT
  • Radium-223
  • Reconstruction
  • Theranostics
  • α-particle radiopharmaceutical therapies


Dive into the research topics of 'A list-mode multi-energy window low-count SPECT reconstruction method for isotopes with multiple emission peaks'. Together they form a unique fingerprint.

Cite this