en Radiation Biology Radiation Biology تحقيق بديع Original Research <div style="text-align: justify;"><span style="font-size:10pt"><span style="text-justify:inter-word"><span style="line-height:90%"><span style="font-family:Calibri"><span style="color:black"><span lang="en-US" style="font-size:9.0pt"><span style="line-height:90%"><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><span lang="en-US" style="font-size:9.0pt"><span style="line-height:90%"><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> <span lang="en-IN" style="font-size:9.0pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="color:#1c1d1e"><span style="language:en-IN">Treatment planning for Hippocampal avoidance whole-brain radiotherapy (ha-WBRT) is demanding and time-consuming due to the position of the Hippocampus and low dose tolerances. This study evaluates the feasibility of fixed field volumetric modulated arc therapy (fVMAT) for ha-WBRT using the Elekta Agility&trade; collimator system and Monaco treatment planning system. </span></span></span></span></span><span lang="en-IN" style="font-size:9.0pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-style:italic"><span style="font-weight:bold"><span style="language:en-IN">Materials and Methods</span></span></span></span></span></span></span><span lang="en-IN" style="font-size:9.0pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-weight:bold"><span style="language:en-IN">: </span></span></span></span></span></span><span lang="en-IN" style="font-size:9.0pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="color:#1c1d1e"><span style="language:en-IN">Fifteen patients treated for WBRT were subjected to fVMAT and conventional VMAT (cVMAT) planning with similar optimisation criteria. Jaws were restricted above and below the Hippocampus for the fVMAT plans with isocenter positioned at the brain&#39;s center, dividing the brain target into two. In contrast, Jaws were not restricted for cVMAT plans. Plans were compared in terms of dose constraints, dose conformity, and dose homogeneity. Plan complexity was compared in terms of modulation degree (MD), and delivery efficiency was checked by performing patient-specific quality assurance. </span></span></span></span></span><span lang="en-IN" style="font-size:9.0pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-style:italic"><span style="font-weight:bold"><span style="language:en-IN">Results</span></span></span></span></span></span></span><span lang="en-IN" style="font-size:9.0pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-weight:bold"><span style="language:en-IN">:</span></span></span></span></span></span> <span lang="en-IN" style="font-size:9.0pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="color:#1c1d1e"><span style="language:en-IN">Both plans met the RTOG-0933 dose requirements. The fVMAT plans showed statistically significant improved target coverage (D</span></span></span></span></span><span lang="en-IN" style="font-size:5.9939pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="color:#1c1d1e"><span style="language:en-IN">_98%,</span></span></span></span></span><span lang="en-IN" style="font-size:9.0pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="color:#1c1d1e"><span style="language:en-IN">V</span></span></span></span></span><span lang="en-IN" style="font-size:5.9939pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="color:#1c1d1e"><span style="language:en-IN">_30Gy</span></span></span></span></span><span lang="en-IN" style="font-size:9.0pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="color:#1c1d1e"><span style="language:en-IN">), </span></span></span></span></span><span lang="en-IN" style="font-size:9.0pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="language:en-IN">target homogeneity, and conformity. There was no statistically significant change in hippocampus doses between the two plans. The fVMAT plans showed lesser plan complexity with average MD of 3.34&plusmn;0.5 compared to cVMAT plans (average MD of 4.21&plusmn;0.4, p=0.00011).</span></span></span></span><span lang="en-IN" style="font-size:9.0pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="color:#1c1d1e"><span style="language:en-IN"> The increased plan complexity was reflected in the delivery efficiency as cVMAT showed higher average gamma failure for patient3.84%(p=0.0004) and a target volume 7.13% (p=0.0359) structures. </span></span></span></span></span><span lang="en-IN" style="font-size:9.0pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-style:italic"><span style="font-weight:bold"><span style="language:en-IN">Conclusions</span></span></span></span></span></span></span><span lang="en-IN" style="font-size:9.0pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-weight:bold"><span style="language:en-IN">:</span></span></span></span></span></span> <span lang="en-IN" style="font-size:9.0pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="language:en-IN">According to the obtained results, the </span></span></span></span><span lang="en-IN" style="font-size:9.0pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="color:#1c1d1e"><span style="language:en-IN">Elekta Agility&trade; collimator system and Monaco treatment planning system</span></span></span></span></span><span lang="en-IN" style="font-size:9.0pt"><span style="line-height:90%"><span style="font-family:Calibri"><span style="language:en-IN"> can generate better ha-WBRT plans using the fVMAT technique.</span></span></span></span></span></span></span></span></span></div> Treatment planning, VMAT, whole brain radiotherapy, hippocampus sparing. 105 109 http://ijrr.com/browse.php?a_code=A-10-1-1012&slc_lang=en&sid=1 R. Vysakh vysakhraveendran92@gmail.com 7900319475328460023113 7900319475328460023113 Yes Department of Physics, Noorul Islam Centre for Higher Education, Kumaracoil- 629 180, Kanyakumari District, Tamil Nadu, India R. Ganapathi Raman 7900319475328460023114 7900319475328460023114 No Department of Medical Physics, MVR Cancer Centre & Research Institute, Calicut, India S.O. Muhammed 7900319475328460023115 7900319475328460023115 No Department of Medical Physics, Anna University, Chennai, India N. Puzhakkkal 7900319475328460023116 7900319475328460023116 No Department of Physics, Noorul Islam Centre for Higher Education, Kumaracoil- 629 180, Kanyakumari District, Tamil Nadu, India