图像引导下头颈部肿瘤固定装置改良的误差分析

Error Coparison of Image Guided Head Neck Tumor Improved Fixing Device

目的:在调强放射治疗过程中,采用同样的放射治疗手段(高能X线或电子线治疗),而通过改良头颈部体位的固定装置,能有效减少放射治疗摆位中产生的随机误差。方法:随机选取不同固定装置的两组鼻咽癌患者各82人,应用Varian Trilogy直线加速器对每位患者进行一周一次的CBCT扫描,并与计划系统的定位CT图像进行在线校准匹配,得到X(左右)、Y(头脚)、Z(腹背)三个方向上的实时摆位误差。采集两组患者所有的摆位误差数据进行对比分析。结果:旧固定装置摆位误差X方向约0.0984 cm,Y方向0.1870 cm,Z方向约0.0979 cm;新固定装置摆位误差X方向约0.0801cm,Y方向0.1027 cm,Z方向约0.0889 cm(注:X代表Lateral,Y代表Longitudinal,Z代表Vertical)。两组固定装置在X方向和Z方向上摆位误差区别不大,但新固定装置在Y方向上明显提高了放射治疗的精确性,大大减少了随机误差。结论:有效地使正常组织受到最少照射和提高肿瘤的局部控制率,减少正常组织并发症,治疗体位的精确最为关键。通过改良体位固定装置,严格按照CBCT验证后的数据摆位,能有效减少来自摆位的随机误差。同时,保证了治疗体位的精确性和重复性,提高了放疗精度。

Objective：in the process of intensity-modulated radiotherapy,using the same radiation treatment（the high energy X-ray or electron beam therapy）,and through the improvement of head and neck position fixing device,can reduce the random errors caused by radiotherapy in placement effectively.Methods：randomly selected from different fixing device of two groups of patients with nasopharyngeal carcinoma,82 each,application of Varian trilogy linear accelerator for each patient CBCT scanning once a week,and the positioning ofthe CT images and planning system for on-line calibration match,get X（or so）,Y（head）,Z（under） the real-time beam position error on the three directions.The positioning error of two groups of patients with all data were analyzed.Results：the old fixed device placement error is about 0.0984 cm X direction,Y direction is 0.1870 cm,Z direction is about 0.0979 cm;New fixtures beam position error is about 0.0801 cm X direction,Y direction is 0.1027 cm,Z direction is about 0.0889 cm（note：on behalf of the Lateral X,Y represents the Longitudinal,Z represents the Vertical）.Two sets of fixtures in the X direction and Z direction on bit error difference is not big,but the new fixtures in the Y direction obviously improves the accuracy of radiation treatment,greatly reduce the random error.Conclusions：make normal tissue is the least illuminate effectively and improve the local control of tumor,reduce normal tissue complications,treatment of preciselythe most critical position.Through improved position fixing device,in strict accordance with the CBCT validated data placement,can effectively reduce the random error from the placement.At the same time,guarantee the accuracy and repeat ability of treatment position,improved the precision of radiotherapy.