## 5 Conclusions  
In conclusion, our study suggests that the use of \({}^{99\text{m}}\)Tc SPECT acquisitions, together with the local energy deposition dose computational method, outperforms bremsstrahlung SPECT imaging and provide results similar to Monte Carlo calculation for liver lesions exceeding the SPECT resolution limit. For liver lesions with hypoxic necrotic core or lesions whose size is close to the SPECT system resolution, a preliminary characterization of the system should be performed comparing the scanner performance against a reference phantom or geometry standard. Against this backdrop, an accurate characterization of the SPECT scanner has the potential to provide a set of quantifiable results and specific metrics that may serve as a point of reference against which clinical data can be compared. Further research is needed to extend results to different SPECT/CT systems and additional anthropomorphic phantom. In addition, further studies aiming at assessing the impact of different image processing/reconstruction software could prove quite beneficial to the literature. Conceptualization, S.U., M.D. and L.S. ; methodology, E.M., S.U. and S.U. ; validation, G.P., E.M. and S.R. ; formal analysis, S.U., M.D. and E.M.; investigation, S.U. and M.D. ; data curation, S.U., M.D., G.P., G.V. and A.S.; writing--original draft preparation, S.U., L.S., A.I. and M.D. ; writing--review and editing, E.M., M.D. and L.S. ; supervision R.S. ; project administration, R.S. and L.S. All authors have read and agreed to the published version of the manuscript. This work was partially supported by the grant from the Associazione Italiana per la Ricerca sul Cancro (AIRC) to LS (IG #20809). Not applicable. The AbdoMan phantom used in this research work was kindly provided by [PERSON] and [PERSON]. The authors declare no conflict of interest. The following abbreviations are used in this manuscript: \begin{tabular}{l l} RE & Radioembolization \\ SPECT & Single Photon Emission Computed Tomography \\ OSEM & Ordered Subset Expectation Maximization \\ CT & Computed Tomography \\ VOI & Volume of Interest \\ PET & Positron Emission Tomography \\ MAA & Macroaggregated Albumin \\ DKM & dose kernel method \\ LDM & local energy deposition method \\ DVHs & dose volume histograms \\ \(\upmu\)s & microspheres \\ EBRT & External Beam Radiotherapy \\ \end{tabular}   
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