宫颈癌患者调强放疗中放疗设备间的系统误差探究

目的:分析宫颈癌患者调强放疗（intensity-modulated radiotherapy，IMRT）中不同的治疗直线加速器存在的系统误差与随机误差。方法:选择2019年10月至2021年11月在中山大学肿瘤防治中心Varian Vital_Beam加速器和Elekta Versa_HD加速器接受IMRT的宫颈癌患...

Exploring the systematic error of radiotherapy equipment in intensity-modulated radiotherapy for patients with cervical cancer

Objective To analyze the systematic and random errors of different treatment linear accelerators in intensity-modulated radiotherapy (IMRT) for patients with cervical cancer. Methods From October 2019 to November 2021, 320 cervical cancer patients who were 32-75 years old and received IMRT with Varian Vital_Beam accelerator and Elekta Versa_HD accelerator in Sun Yat-sen University Cancer Center were selected. After the design of the radiotherapy plan was completed, we performed the X-ray simulation positioning machine reset verification according to the bed moving parameters of the treatment plan for each patient, and used the cone beam CT (CBCT) for body position verification during the treatment, including 960 CBCT positioning error data. The body position error data after CBCT calibration were recorded and analyzed by paired t-test. Results The positioning errors of the Varian Vital_Beam and Elekta Versa_HD linear accelerators in the superior-inferior (SI), left-right (LR), and anterior-post (AP) translation directions were (0.00±0.32) cm, (0.00±0.25) cm, (0.04±0.24) cm and (0.08±0.40) cm, (0.02±0.33) cm, (0.04±0.25) cm; there were statistically significant differences in the SI and AP directions (both P<0.05), while there was no statistically significant difference in the LR direction (P> 0.05). The positioning errors of the Varian Vital_Beam and Elekta Versa_HD linear accelerators in the RTN, Pitch, and Roll rotation directions were (0.12±1.00)°, (0.81±1.33)°, (0.32±0.64)° and (0.24± 0.73)°, (0.28±1.64)°, (0.01±0.80)°; there were statistically significant differences (all P<0.05). The total systematic error errors of Varian Vital_Beam linear accelerator in the SI, LR, AP, RTN, Pitch, and Roll directions were 0.29 cm, 0.22 cm, 0.22 cm, 0.81°, 1.46°, and 0.63°; the total systematic error errors of Elekta Versa_HD linear accelerator in the SI, LR, AP, RTN, Pitch, and Roll directions were 0.37 cm, 0.30 cm, 0.23 cm, 0.69°, 1.44°, and 0.72°. The total random errors of Varian Vital_Beam linear accelerator in the SI, LR, AP, RTN, Pitch, and Roll directions were 0.23 cm, 0.18 cm, 0.14 cm, 0.98°, 0.87°, and 0.55°; the total random errors of Elekta Versa_HD linear accelerator in the SI, LR, AP, RTN, Pitch, and Roll directions were 0.28 cm, 0.23 cm, 0.15 cm, 0.54°, 1.02°, and 0.56°. Conclusions The systematic errors of different radiotherapy equipment are different. In the SI, LR, AP, and Roll directions, the systematic error of Varian Vital_Beam is smaller than that of Elekta Versa_HD; while in the RTN and Pitch directions, the systematic error of Varian Vital_Beam is greater than that of Elekta Versa_HD.