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Investigation of interfractional esophageal motions and its dosimetric effect in patients who underwent radiochemotherapy with esophageal carcinoma
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E.S. Akovalı   , G. Can , S. Karaçam , D.Ç. Öksüz |
| Istanbul University-Cerrahpaşa, Cerrahpaşa Medical Faculty, Department of Radiation Oncology, Istanbul,Turkey , eminesedef88@gmail.com |
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Abstract: (28 Views) |
Background: 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. Materials and Methods: 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 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. Results: The interfractional displacement of the abdominal esophagus in all directions was found statistically significantly higher than other part of the esophagus. The minimum PTV 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. Conclusion: 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. |
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| Keywords: Esophageal cancer, interfractional esophageal motion, CBCT. |
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Full-Text [PDF 983 kb]
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Type of Study: Original Research |
Subject:
Radiation Biology
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