Application of the double-center setup in the precise radiotherapy for middle esophageal carcinoma / 肿瘤研究与临床

ABSTRACT

Objective To compare the errors of double-center and single-center setup, and to study the role of both on reducing the rotational setup errors for the patients with esophageal carcinoma depend on rigid registration errors between online kV-cone-beam computed tomography (kV-CBCT) images and plans for CT images. Methods 20 patients with middle esophageal carcinoma received image scanning before treatment every week by using double-center setup and CBCT, and single-center setup images of 20 patients were taken from the X volume image (XVI) system. Then the images of both setup types, registration errors of CT image and rotational setup errors were compared respectively. Every patient received kV-CBCT scanning analysis before treatment every week, and 6 times in total. 240 group of kV-CBCT images from all of the patients were off-line matched with plans for CT images to calculate the errors of X-axis, Y-axis, Z-axis. Then the data of linear errors and rotational setup errors from patients were collected, aiming at putting the error data into the patients treatment program and analyzing the significances. Results The standard registration of double-center setup was as follows: T (X) (0.28 ±0.19) cm, T (Y) (0.27 ±0.19) cm, T (Z) (0.33 ±0.12) cm, R (X) (0.40 ±0.19)° , R (Y) (0.30 ±0.18)° , R (Z) (0.30 ±0.19)° . The standard registration of single-center setup was as follows:T(X) (0.32±0.20) cm, T(Y) (0.29±0.25)cm, T(Z) (0.31±0.16) cm, R(X) (2.2±0.68)°, R(Y) (0.5±0.32)°, R(Z) (2.10±0.60)°. There were statistical differences between linear errors in T(X) and rotational setup errors in R(X), R(Y) or R(Z) (P< 0.05). Conclusion Double-center position can reduce the rotational setup errors, especially in X-axis, Y-axis errors, and may provide more help for the radiation oncology departments without on-board CBCT.