The effects of mismatch between SPECT and CT images on quantitative activity estimation - A simulation study.

Background: Quantitative activity estimation is essential in nuclear medicine imaging. Mismatch between SPECT and CT images at the same imaging time point due to patient movement degrades accuracy in both diagnostic studies and target radionuclide therapy dosimetry. This work aims to study the mismatch effects between CT and SPECT data on attenuation correction (AC), volume-of-interest (VOI) delineation, and registration for activity estimation.

Technical note: Respiratory impacts on static and respiratory gated Tc-MAA SPECT/CT for liver radioembolization: A simulation study.

Purpose: We aimed to evaluate respiratory impacts on static and respiratory gated (RG) Tc-MAA SPECT in terms of respiratory motion (RM) blur, attenuation correction (AC), and volume-of-interest (VOI) segmentation on lung shunt faction (LSF) and tumor-to-normal liver ratio (TNR) estimation for liver radioembolization therapy planning.

Methods: The XCAT phantom was used to simulate a population of 300 phantoms, modeling various anatomical variations, tumor characteristics, RM amplitudes, LSFs, and TNRs. One hundred and twenty noisy projections of average activity maps near end-expiration (End-EX) and whole respiratory cycle were simulated analytically, modeling attenuation and geometric collimator-detector-response (GCDR).