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="color:black"><span style="language:en-US">It has been found that the bystander effect plays a key role in the survival of cells exposed to highly non-uniform radiation beams. However, the linear-quadratic (LQ) model cannot predict these effects well. The present study aimed to explore the potential impact of the radiation-induced signaling effects on treatment plans for spatially fractionated radiation therapy (SFRT) using a numerical radiobiological model.&nbsp;</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">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>&nbsp;<span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:black"><span style="language:en-US">Two tomotherapy-based SFRT plans were created using commercially available software in this work. The tumor response to these plans was modeled by both the conventional LQ model and a bystander model incorporating the indirect effect of radiation. We have investigated how dose-volume histograms (DVHs), dose distribution, equivalent uniform dose (EUD), and mean dose change with radiation-induced signaling effects.&nbsp;</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>&nbsp;<span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:black"><span style="language:en-US">When the intercellular signaling effects are included in the predictive survival model, the cell-killing within the low-dose regions of GRID fields increases. This leads to an increase in the EUD and means dose. These effects are more striking for the LATTICE radiotherapy plan, which contains high dose gradients in three dimensions.&nbsp;</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>&nbsp;<span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:black"><span style="language:en-US">Incorporating radiation-induced signals in tumor cells response to SFRT significantly deviates from the LQ model predictions. Therefore, it is recommended to use the radiobiological models which take both the signaling and radiation effects into account to predict survival in highly modulated radiation beams, especially in LATTICE radiotherapy.</span></span></span></span></span></span></span></span></span></span></div> GRID therapy, spatially fractionated radiotherapy (SFRT), tomotherapy, bystander effect, LATTICE radiotherapy. 657 664 http://ijrr.com/browse.php?a_code=A-10-1-960&slc_lang=en&sid=1 F. Mahmoudi 7900319475328460022141 7900319475328460022141 No Department of Medical Physics, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran D. Shahbazi-Gahrouei shahbazi24@yahoo.com 7900319475328460022142 7900319475328460022142 Yes Department of Medical Physics, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran N. Chegeni 7900319475328460022143 7900319475328460022143 No Department of Medical Physics, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran M. Saeb 7900319475328460022144 7900319475328460022144 No Department of Medical Physics, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran V. Sadeghi 7900319475328460022145 7900319475328460022145 No Department of Biomedical Engineering, Faculty of Advanced Medical Technology, Isfahan University of Medical Sciences, Isfahan, Iran S. Hemati 7900319475328460022146 7900319475328460022146 No Department of Radiation Oncology, Faculty of Medicine, Seyyed Al-Shohada Hospital, Isfahan University of Medical Sciences, Isfahan, Iran