Evaluation of respiratory-induced target motion for esophageal tumors at the gastroesophageal junction

摘要: Abstract Purpose To quantify the internal motion margin requirements for radiotherapy of tumors near gastroesophageal junction (GEJ). Methods and materials Four-dimensional computed tomography (4DCT) scans were obtained 25 patients with primary located GEJ. The gross tumor volume (GTV) was manually contoured on exhale-phase image from 4DCT set. A deformable registration method used to automatically propagate contours other phases images. target motion, we measured displacement GTV centroid variations in boundary volume. Internal margins calculated lateral (RL), anterior–posterior (AP), superior–inferior (SI) directions. Results mean ± standard deviation peak-to-peak 0.39 ± 0.27 cm (range, 0.04–1.09 cm) RL, 0.38 ± 0.23 cm 0.10–0.94 cm) AP, 0.87 ± 0.47 cm 0.43–2.63 cm) SI directions, respectively. On average, 72% 9–172%) larger than defined a single-phase CT image. Variations boundaries due tissue deformation suggested asymmetric margins: 1.0 cm left [toward stomach], 0.8 cm right, 1.1 cm anterior, 0.6 cm posterior, superior (toward distal esophagus), 1.6 cm inferior stomach). Conclusion Because GEJ are subject marked but amount respiratory-induced intrafractional use may be beneficial.