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="language:en-US">Inverse treatment planning provides superior dose conformity and steep dose gradients, which are essential for Stereotactic Radiosurgery and Radiotherapy (SRS/SRT). Given the critical nature of dose optimization and calculation, this study investigates how different grid sizes and photon fluence smoothing levels influence plan quality outcomes. </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="language:en-US">Using ten SRS/SRT cases, eight distinct planning scenarios were generated by cross-referencing 2 mm and 3 mm grid sizes for both optimization and final dose calculation, alongside two levels of fluence smoothing. Plan quality was evaluated via dose coverage, Homogeneity Index (HI), Conformity Index (CI), and Gradient Distance (GD). Statistical significance was assessed at a 95% confidence interval, utilizing a weighted scoring system to benchmark performance against a standard 2 mm grid protocol. </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="language:en-US">Utilizing a 3 mm grid for optimization followed by a 2 mm grid for final dose calculation yielded significantly better results for dose coverage and GD, though it produced a lower CI. Despite this, the weighted performance scores for this configuration exceeded the benchmark. Furthermore, the level of photon fluence smoothing (low vs. medium) did not significantly impact the plan quality outcome. </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="language:en-US">A larger optimization grid (3 mm) paired with a finer calculation grid (2 mm) produces plan quality comparable to using a fine grid for both stages. These results suggest that planning efficiency can be improved without compromising clinical quality, regardless of the fluence smoothing level.</span></span></span></span></span></span></span></span></span></div> Stereotactic radiosurgery, dose calculation, dose optimization, photon fluence smoothness, treatment planning. 1031 1037 http://ijrr.com/browse.php?a_code=A-10-1-1612&slc_lang=en&sid=1 A. Watcharawipha 7900319475328460034886 7900319475328460034886 No Division of Radiation Oncology, Department of Radiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand W. Nobnop wannapha.n@cmu.ac.th 7900319475328460034887 7900319475328460034887 Yes Division of Radiation Oncology, Department of Radiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand A. Bunnachak 7900319475328460034888 7900319475328460034888 No Division of Radiation Oncology, Department of Radiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand A. Chaiyapong 7900319475328460034889 7900319475328460034889 No Division of Radiation Oncology, Department of Radiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand B. Jia-Mahasap 7900319475328460034890 7900319475328460034890 No Division of Radiation Oncology, Department of Radiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand I. Chitapanarux 7900319475328460034891 7900319475328460034891 No Division of Radiation Oncology, Department of Radiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand