en Radiation Biology Radiation Biology تحقيق بديع Original Research <div style="text-align: justify;"><span style="font-size:10pt"><span style="text-justify:newspaper"><span style="text-kashida-space:50%"><span style="line-height:119%"><span style="font-family:Calibri"><span style="color:black"><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-style:italic"><span style="font-weight:bold"><span style="language:en-US">Background</span></span></span></span></span></span><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-weight:bold"><span style="language:en-US">:</span></span></span></span></span> <span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="language:en-US">This study aims to investigate voxel-level dose calculation methods and improve its calculation efficiency in nuclear medicine that can consider animal-specific heterogeneous tissue compositions and radiopharmaceutical biodistributions simultaneously. </span></span></span><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-style:italic"><span style="font-weight:bold"><span style="language:en-US">Materials and Methods</span></span></span></span></span></span><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-weight:bold"><span style="language:en-US">:</span></span></span></span></span> <span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="language:en-US">The voxelized mouse phantom was constructed from real mouse CT images and simulated using the Monte Carlo GEANT4 code. According to the dynamic PET images of real mouse, the real distribution of radiopharmaceutical activity was set in the Monte Carlo simulation. The sampling method to improve the calculation efficiency was proposed. Two voxel-level dose calculation methods were implemented in this study. The average absorbed dose in vital target organs and the tumor was calculated by the proposed voxel-level dose calculation methods and the traditional MIRD method respectively. The results of the average absorbed dose calculated by the two methods were compared. Based on the voxel-level dose calculation method, the three-dimensional dose distribution in organs and the tumor was obtained and evaluated</span></span></span><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="font-weight:bold"><span style="language:en-US">. </span></span></span></span><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-style:italic"><span style="font-weight:bold"><span style="language:en-US">Results</span></span></span></span></span></span><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-weight:bold"><span style="language:en-US">:</span></span></span></span></span> <span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:black"><span style="language:en-US">The relative difference of average absorbed dose between the two voxel-level dose calculation methods was</span></span></span></span> <span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:black"><span style="language:en-US">mostly less than 10%. The sampling method proposed to improve calculation efficiency for the voxel-level dose calculation can decrease the calculation time by ~34% with less deviation. </span></span></span></span><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-style:italic"><span style="font-weight:bold"><span style="language:en-US">Conclusion</span></span></span></span></span></span><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-weight:bold"><span style="language:en-US">: </span></span></span></span></span><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="language:en-US">The results confirmed that </span></span></span><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:black"><span style="language:en-US">the voxel-level dose calculation methods proposed in this study allow for more accurate and efficient assessment of the internal radiation dose.</span></span></span></span></span></span></span></span></span></span></div> <span style="font-size:10pt"><span style="line-height:119%"><span style="font-family:Calibri"><span style="color:black">&nbsp;</span></span></span></span><br> &nbsp; Internal dosimetry, radiopharmaceutical, Monte Carlo simulation, MIRD. 317 322 http://ijrr.com/browse.php?a_code=A-10-1-910&slc_lang=en&sid=1 H. Liu 7900319475328460021552 7900319475328460021552 No Department of Nuclear Science and Technology Nanjing University of Aeronautics and Astronautics,29 General Road, Jiangning District, Nanjing 211106, China C. Geng gengchr@nuaa.edu.cn 7900319475328460021553 7900319475328460021553 Yes Department of Nuclear Science and Technology Nanjing University of Aeronautics and Astronautics,29 General Road, Jiangning District, Nanjing 211106, China X. Tang 7900319475328460021554 7900319475328460021554 No Department of Nuclear Science and Technology Nanjing University of Aeronautics and Astronautics,29 General Road, Jiangning District, Nanjing 211106, China L. Tang 7900319475328460021555 7900319475328460021555 No MITRO Biotech Co., Ltd, Building 8, No.5 Qiande Road, Nanjing 211106, 211106, China X. Li 7900319475328460021556 7900319475328460021556 No MITRO Biotech Co., Ltd, Building 8, No.5 Qiande Road, Nanjing 211106, 211106, China P. Xu 7900319475328460021557 7900319475328460021557 No Department of Nuclear Science and Technology Nanjing University of Aeronautics and Astronautics,29 General Road, Jiangning District, Nanjing 211106, China