不同部位肿瘤患者在立体定向放射治疗中摆位误差分析及控制方法

Setup error analysis and control methods for patients with cancer in different position in stereotactic radiotherapy

目的在立体定向放射治疗中，对不同部位肿瘤患者摆位误差进行测量与分析，探讨其影响因素及控制方法。方法选取54例肿瘤患者，其中17例脑转移患者，27例转移性或原发性肺癌患者，10例转移性肝癌患者，行立体定向放射治疗，治疗前行CBCT扫描，并结合扫描结果确定靶区，对靶区中心在X、Y、Z轴上的摆位误差进行统计分析。结果头部摆位误差较小，其误差平均值〈1mm，而胸腹部患者的摆位误差则相对较大，平均值〈3mm，但头部和胸腹部的摆位误差均控制在精确放射治疗的要求范围内；对X轴、Y轴以及Z轴三个方向的误差范围和平均值来看，胸腹部放射治疗的患者比头部放射治疗的患者摆位重复性准确率低。结论胸腹部摆位极易受患者的呼吸、体质量变化以及膀胱充盈度等因素的影响而发生变化，通过对影响因素进行综合分析，采取相应的控制措施，提高放疗重复摆位精度。

Objective To measure and analyze positioning error of stereotactic radiation therapy for patients with cancer in different position, and to investigate the influencing factors and control methods. Methods Selected 54 patients and conducted stereotactic radiotherapy treatment, including 17 cases of brain metastases, 27 cases of metastatic or primary lung cancer and l0 patients with metastatic liver cancer. CBCT scan was performed, and the target was determined according to the scan results. The positioning error of the target center in X, Y, Z axis were statistical analyzed. Results Head positioning error is small, and the error is less than the average of I mm, and the patient＇ s chest and abdomen setup errors are relatively large, in the average of within 3 mm, and the head and chest and abdomen bit errors are controlled precision radiotherapy within the required range, the X-axis, Y-axis, Z-axis and the average of the three directions, and the error range of the Z axis, the positioning repeatability in patients with thoracic and abdominal radiation therapy were in lower accuracy than patients with head radiation therapy. Conclusions Thoracic and abdominal position can be easily affected by patient breathing, weight changes, bladderand filling and other factors. Through a comprehensive analysis of the factors, appropri- ate measures are suggested to be taken to improve the accuracy of radiotherapy repeat positioning.