Detection of esophageal fiducial marker displacement during radiation therapy with a 2-dimensional on-board imager: analysis of internal margin for esophageal cancer.

摘要: Purpose To quantify the interfraction displacement of esophageal fiducial markers for primary cancer radiation therapy. Methods and Materials Orthogonal 2-dimensional (2D) matching records fused to vertebrae were analyzed in clinically staged T1/2N0 patients undergoing endoscopic clipping as metal markers. Displacement between digitally reconstructed radiographs on-board kilovoltage images during therapy was according direction site. Results Forty-four patients, with 81 (10 proximal, 42 middle, 29 distal), underwent 367 2D sessions The mean (SD) absolute marker 0.26 (0.30) cm right–left (RL), 0.50 (0.39) superior–inferior (SI), 0.24 (0.21) anterior–posterior (AP) direction. significantly larger SI than RL AP directions ( P Conclusions magnitude clips direction, particularly distal esophagus, but substantial observed other at sites. It is practical take estimated movements into account internal margins, even if vertebrae-based performed.