Application of radiotherapy with the extension of spinal cord for esophageal cancer / 中华放射肿瘤学杂志

ABSTRACT

Objective:To analyze the setup and residual errors of spinal cord during online CT-guided radiotherapy for patients with esophageal cancer, and to discuss the necessity of segmental extension of spinal cord.Methods:According to the radiotherapy site, 60 cases of esophageal cancer were divided into the neck, chest and abdomen groups, 20 cases in each group. Cervical pleura or vacuum bag was fixed, IMRT technology was adopted, and pre-treatment CT images were obtained by CT Vision, and 20 consecutive CT scans were collected for each case. CT images were imported into MIM software. The parameters of the setup errors were processed and extracted. The CT spinal cord was delineated for verification and planning, and the Dice coefficient, Hausdorff maximum distance and centroid coordinate of the delineated spinal cord were processed and extracted. Compatibility anova data were adopted. The calculation formula of the extension margin is M PRV= 1.3 ∑ total+ 0.5 σ total. Results:Residual centroid method was employed. Non-on-line and on-line CT-guided radiotherapy, the extension margins of neck, chest, abdominal spinal cord in the x-, y-and z-axis were 3.86, 5.37, 6.36 mm; 3.45, 3.83, 4.51 mm; 4.05, 4.83, 7.06 mm, vs, 2.85, 2.19, 2.83 mm; 2.32, 2.20, 2.16 mm; 2.86, 2.21, 2.83 mm, respectively. During residual Hausdorff distance method, non-on-line and on-line CT guided radiotherapy, the extension margins of neck, chest, abdominal spinal cord in the x-, y-and z-axis were 3.10, 5.33, 6.15 mm; 3.30, 3.77, 4.61 mm; 3.35, 4.76, 6.87 mm, vs, 2.12, 2.06, 2.32 mm; 2.12, 2.06, 2.32 mm; 2.12, 2.06, 2.32 mm, respectively.Conclusion:The setup errors and residual errors are different in each segment of spinal cord. Henc, different extension margins should be given.