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-GB" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:black"><span style="language:en-GB">The aim of this study was to evaluate interfractional esophageal motions using kilovoltage cone-beam computed tomography (kV-CBCT) in patients who underwent chemoradiotherapy for esophageal cancer. </span></span></span></span><span lang="en-GB" 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-GB">Materials and Methods: </span></span></span></span></span></span><span lang="en-GB" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:black"><span style="language:en-GB">Sixteen patients treated with intensity modulated radiation therapy or volume modulated arc therapy were included. For each patient, one kV-CBCT per week was used for the assessments. Upper, middle, distal thoracic esophagus and abdominal esophagus was contoured on planning CT (pCT) and each kV-CBCT images. Each kV-CBCTs was fused with the&nbsp; pCT after automatic vertebrae-matching rigid registration, thus only esophageal motion was taken into account. The displacement of the esophageal center points was calculated on the left-right (LR), anterior-posterior (AP), cranio-caudal (CC) directions. It was investigated whether the outer contour of the esophagus remained within the 95% isodose line in the treatment plan. </span></span></span></span><span lang="en-GB" 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-GB">Results: </span></span></span></span></span></span><span lang="en-GB" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:black"><span style="language:en-GB">The interfractional displacement of the abdominal esophagus in all directions was found statistically significantly higher than other part of the esophagus. The minimum PTV&nbsp; margin of 1.03 cm for AP, 1.03 cm for CC and 1.05 cm for LR direction was required. The minimum margin needed for covering 95% of the tumor motion in LR, AP, CC directions, respectively, were 0.8, 0.8 and 0.7 cm for the abdominal esophagus. Isodose coverage of 95% were similar for all esophageal segments in pCT and combined kV-CBCT volume. </span></span></span></span><span lang="en-GB" 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-GB">Conclusion: </span></span></span></span></span></span><span lang="en-GB" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:black"><span style="language:en-GB">Interfractional position changes were largest in all directions in the abdominal esophagus. Reducing of PTV margin for the distal thoracic and abdominal esophagus may not be suitable for clinical practice.</span></span></span></span></span></span></span></span></span></span></div> Esophageal cancer, interfractional esophageal motion, CBCT. 129 134 http://ijrr.com/browse.php?a_code=A-10-1-1466&slc_lang=en&sid=1 E.S. Akovalı eminesedef88@gmail.com 7900319475328460032875 7900319475328460032875 Yes Istanbul University-Cerrahpaşa, Cerrahpaşa Medical Faculty, Department of Radiation Oncology, Istanbul,Turkey G. Can 7900319475328460032876 7900319475328460032876 No Istanbul University-Cerrahpaşa, Cerrahpaşa Medical Faculty, Department of Public Health, Istanbul,Turkey S. Karaçam 7900319475328460032877 7900319475328460032877 No Istanbul University-Cerrahpaşa, Cerrahpaşa Medical Faculty, Department of Radiation Oncology, Istanbul,Turkey D.Ç. Öksüz 7900319475328460032878 7900319475328460032878 No Istanbul University-Cerrahpaşa, Cerrahpaşa Medical Faculty, Department of Radiation Oncology, Istanbul,Turkey