Setup error in three-dimensional conformal radiotherapy for thoracic esophageal carcinoma
10.3760/cma.j.issn.1004-4221.2009.03.182
- VernacularTitle:胸段食管癌三维适形放疗摆位误差研究
- Author:
Jinsheng HONG
;
Weijian ZHANG
;
Jinmei CHEN
;
Chuanshu CAI
;
Chunlin KE
;
Xiuying CHEN
;
Bin WU
;
Feibao GUO
- Publication Type:Journal Article
- Keywords:
Esophageal neoplasm/radiotherapy;
Radiotherapy,three-dimensional conformal;
Setup error;
Electronic portal imaging device
- From:
Chinese Journal of Radiation Oncology
2009;18(3):182-185
- CountryChina
- Language:Chinese
-
Abstract:
Objective To study the setup errors in three-dimensional conformal radiotherapy (3DCRT) for thoracic esophageal carcinoma using electronic portal imaging device(EPID) and calculate the margins from CTV to PTV. Methods Forty-one patients with thoracic esophageal carcinoma who received 3DCRT were continuously enrolled into this study. The anterior and lateral electronic portal images (EPI) were aquired by EPID once a week. The setup errors were obtained through comparing the difference between EPI and digitally reconstructed radiographs(DRR). Then the setup margins from CTV to PTV were calculat-ed. By using self paired design,22 patients received definitive radiotherapy with different margins. Group A: the margins were 10 mm in all the three axes;Group B: the margins were aquired in this study. The differ-ence were compared by Paired t-test or Wilcoxon signed-rank test. Results The margins from CTV to PTV in x,y and z axes were 8.72 mm, 10.50 mm and 5.62 mm, respectively. Between the group A and group B, the difference of the maximum dose of the spinal cord was significant(4638.7 cGy±1449.6 cGy vs. 4310.2 cGy±1528.7 cGy; t=5.48, P=0.000), and the difference of NTCP for the spinal cord was also significant (4.82%±5.99% vs. 3.64%±4.70%;Z=-2.70,P=0.007). Conclusions For patients with tho-racic esophageal carcinoma who receive 3DCRT in author's department,the margins from CTV to PTV in x, y and z axes were 8.72 mm, 10.50 mm and 5.62 mm, respectively. The spinal cord could be better protected by using these setup margins than using 10 mm in each axis.
