CBCT X射线图像引导技术在直肠癌IMRT放疗中的应用

Application of CBCT X-Ray Image-Guided Technique in IMRT Radiotherapy for Rectal Cancer

摘要: 目的：探讨锥体束计算机断层扫描(CBCT) X射线图像引导技术在直肠癌调强放疗(IMRT)中的作用。方法：回顾性分析2022年1月至2023年6月于日照市人民医院放疗科行IMRT放疗的15例直肠癌患者的临床资料。病人治疗摆位完成后采用CBCT X射线图像引导获得扫描图像，与数字重建放射影像(DRR)进行匹配，得到3个方向的平移摆位误差和3个方向的旋转摆位误差，并进行统计分析，最后得出锥体束计算机断层扫描(CBCT) X射线图像引导技术在直肠癌调强放疗(IMRT)中的作用。结果：15例患者的位置验证均采用CBCT扫描，共获取375组X射线图像，分别与治疗计划DRR进行图像配准然后得出每次治疗的摆位误差。平移方向上Y (头、脚)方向的平移摆位误差最大，摆位误差为(2.245 ± 0.709) cm；X (左、右)方向次之，摆位误差为(0.623 ± 0.203) cm；Z (胸、背)方向最小，摆位误差为(0.492 ± 0.163) cm。旋转方向上RTN (左、右)方向的旋转摆位误差最大，摆位误差为(4.333 ± 1.121)˚；ROLL (胸、背)方向次之，摆位误差为(3.94 ± 0.809)˚；PITCH (头、脚)方向最小，摆位误差为(2.94 ± 1.195)˚。结论：患者治疗前先做CBCT X射线图像引导可观察到摆位误差之大，待修正之后再行放疗可以进一步减小摆位误差，提高放疗的精确度。

Abstract: Objective: To investigate the role of cone beam computed tomography (CBCT) X-ray image-guided technique in intensity-modulated radiotherapy (IMRT) for rectal cancer. Methods: The clinical data of 15 patients with rectal cancer who underwent IMRT radiotherapy in the radiotherapy depart-ment of Rizhao People’s Hospital from January 2022 to June 2023 were retrospectively analyzed. After the patient’s treatment positioning was completed, the CBCT X-ray image guidance was used to obtain the scanning image, which was matched with the digital reconstruction radiography (DRR) to obtain the translation positioning error in three directions and the rotation positioning error in three directions, and statistical analysis was performed. Finally, the role of cone beam computed tomography (CBCT) X-ray image guidance technology in intensity-modulated radiotherapy (IMRT) for rectal cancer was obtained. Results: CBCT scan was used to verify the position of 15 patients. A total of 375 sets of X-ray images were obtained, which were registered with the treatment plan DRR respectively, and then the setup error of each treatment was obtained. In the translation direction, the translation positioning error in the Y (head and foot) direction was the largest, and the posi-tioning error was (2.245 ± 0.709) cm. The X (left and right) direction was the second, and the setup error was (0.623 ± 0.203) cm. The Z (chest and back) direction was the smallest, and the positioning error was (0.492 ± 0.163) cm. In the rotation direction, the rotation positioning error in the RTN (left and right) direction was the largest, and the positioning error is (4.333 ± 1.121) degrees. The ROLL (chest and back) direction was the second, and the setup error was (3.94 ± 0.809) degrees. The direction of PITCH (head and foot) was the smallest, and the positioning error was (2.94 ± 1.195) degrees. Conclusions: CBCT X-ray image guidance before treatment can observe the large setup error. Radiotherapy after correction can further reduce the setup error and improve the ac-curacy of radiotherapy.