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">The main purpose of this study is to investigate different methods of radiotherapy (RT) using coplanar three-dimensional conformal RT (3D-CRT (cp)), non-coplanar 3D-CRT RT (3D-CRT (ncp)) and helical tomotherapy (HT) techniques to find the optimal method to treat gastric cancer patients.&nbsp;</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">Twenty patients with gastric cancer were retrospectively enrolled. Three different treatment plans including HT, 3D-CRT (cp) and 3D-CRT (ncp) were generated and optimized for each patient. All plans were then evaluated with respect to dosimetric parameters exported from dose-volume histogram curves of target and organ-at-risk (OAR). SPSS software was used for statistical analysis.&nbsp;</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">The conformity index in the target was similar for all plans (p > 0.05), but HT showed significantly better homogeneity compared to the two 3D-CRT methods (p-value < 0.05). Compared to the 3D-CRT (cp) and 3D-CRT (ncp) plans, the HT plans significantly reduced the mean dose, V13 and V20 values of the kidneys (p-Value < 0.05); V5 values of both kidneys were lower in the 3D-CRT (ncp) plan compared to 3D-CRT (cp) and HT. The difference was statistically significant. Moreover, the results proved that the 3D-CRT (ncp) could better preserve kidneys rather than 3D-CRT (cp). Dmean of the liver for HT plans (20.03) was significantly higher than those for both coplanar and non-coplanar 3D-CRT plans (17.86 and 17.7, respectively). </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">Generally, HT plans appear to be the best, but in the case of selecting an optimum method, it is necessary to pay attention to the location of tumors compared to OARs.</span></span></span></span></span></span></span></span></span></div> Gastric cancer, helical tomotherapy, three‑dimensional conformal radiotherapy. 837 843 http://ijrr.com/browse.php?a_code=A-10-1-1247&slc_lang=en&sid=1 A. Kazemzadeh 7900319475328460028387 7900319475328460028387 No Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran L. Mahani 7900319475328460028388 7900319475328460028388 No Department of Radio-Oncology, Seyed-Al-Shohada Hospital, Isfahan University of Medical Sciences, Isfahan, Iran M. Kianinia 7900319475328460028389 7900319475328460028389 No Department of Radio-Oncology, Seyed-Al-Shohada Hospital, Isfahan University of Medical Sciences, Isfahan, Iran A. Shanei Shanei@med.mui.ac.ir 7900319475328460028390 7900319475328460028390 Yes Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran