ABSTRACT
@#<b>Objective</b> To compare the set up errors derived from different registration methods of the X-ray volume imaging (XVI) system for radiotherapy in the treatment of middle/lower-segment esophageal cancer, and to provide a reference for radiation treatment of esophageal cancer. <b>Methods</b> We randomly selected 63 patients with middle/lower-segment esophageal cancer, and obtained their reconstructed XVI images at the first therapy to perform automatic registration with gray-value and bone registration methods. We acquired and compared the three translation errors (along <i>x</i> [left to right], <i>y</i> [head to feet], and <i>z</i> [front to back] axes) and three rotation errors (around the <i>x</i>, <i>y</i>, and <i>z</i> axes) derived from the two registration methods. <b>Results</b> Gray-value registration had significantly smaller translation errors along the <i>x</i> and <i>z</i> axes than bone registration (<i>x</i> azes <i>t</i> = −2.78, <i>z</i> azes <i>t</i> = −2.15, <i>P</i> < 0.05), but there was no significant difference along the <i>y</i> axes (<i>P</i> > 0.05). The rotation errors around the three axes were all smaller than 1°, and were smaller with gray-value registration than with bone registration, but without significant differences (<i>P</i> > 0.05). <b>Conclusion</b> We recommend gray-value registration for radiotherapy in the treatment of middle/lower-segment esophageal cancer. Manual verification or fine-tuning is recommended after automatic registration in clinical practice. Besides translation errors, rotation errors should also be paid attention to.