应用兆伏级锥形束CT校正胸部肿瘤调强放疗摆位误差的研究  

Application of MV cone-beam CT in positioning of thoracic cancer intensity modulated radiotherapy

作　　者：段诗苗[1] 李多杰[1] 张雷[1] 徐全敬[1] 李红伟[1] 

机构地区：[1]安徽省蚌埠医学院第一附属医院放疗科,233004

出　　处：《中华全科医学》2014年第11期1769-1771,共3页Chinese Journal of General Practice

摘　　要：目的应用兆伏级图像引导系统(MV-CBCT)对胸部肿瘤调强放疗摆位误差进行分析,探讨减少摆位误差的方法。方法对接受图像引导放疗的胸部肿瘤患者23例,采用锥形束CT技术采集首次摆位后、摆位误差校正后CBCT图像,并与计划系统的模拟定位CT图像进行匹配,获得首次摆位后、摆位误差校正后在X轴(左右)、Y轴(头脚)、Z轴(腹背)方向摆位误差数值。每位患者每周1次,共采集186组图像,分析校正前后摆位误差的变化情况。结果校正前系统误差±随机误差在X轴、Y轴、Z轴分别为(1.61±1.44)mm、(2.51±2.39)mm、(1.22±1.09)mm,校正后系统误差±随机误差在X轴、Y轴、Z轴分别为(0.89±0.74)mm、(1.07±0.85)mm、(0.76±0.71)mm。依据经典的van-Herk等推理公式MPTV=2.5Σ+0.7δ,计算得出X、Y、Z轴的MPTV值,校正后比校正前分别减少2.1 mm、4.6 mm、1.4 mm。结论应用兆伏级锥形束CT技术,可准确测量摆位误差,通过实时校正,可大大提高患者摆位精度,从而缩小CTV-PTV的摆位外扩边界值,提高放疗的精确性。Objective To investigate set-up errors in intensity modulated radiotherapy for thoracic cancer by using MV grade cone beam CT scanning technique in order to obtain methods to reduce the position error. Methods Patients accepted intensity modulated radiotherapy for thoracic cancer were scanned by MV cone-beam CT before the first radiotherapy and once a week afterward. The offsets of the scan gram from the target centre of treatment planning in right-left（ X ax- is）, anterior-posterior（ Y axis） and superior-interfercr（ Z axis） directions were recorded, then the accuracy of positioning was judged. There were 186 times of scanning of MV CBCT for all 23 patients of the thoracic cancer. Results The systematic and random errors on the X, Y and Z axis were （ 1.61 ± 1.44） mm, （2.51± 2.39） mm, （ 1.22 ± 1.09） mm before correction and （0.89 ± 0.74） mm, （ 1.07 ± 0.85 ） mm, （ 0.76 ± 0.71 ） mm after correction. According to the van Herk formula MPTV = 2.5∑ ± 0.78, the margins in X axis, Y axis, Z axis after auto-repositioning were reduced to 2.1 mm ,4.6 mm and 1.4 mm respectively. Conclusion Using of the MV grade cone-beam CT scan can detect and correct set-up errors accurately and rapidly, thereby it can ameliorate and advance the accuracy of positioning, with which doctors can sketching the opening margin of the target volume in accordance. Application of MV cone-beam CT technology, can accurately measure the position error, through real-time correction, which can greatly improve the patient positioning accuracy. Therefore, the margins from CTV-PTV could be reduced, so as to improve the treatment accuracy.

关 键 词：胸部肿瘤 图像引导放疗 兆伏级锥形束CT 摆位误差 

分 类 号：R734[医药卫生—肿瘤] R735[医药卫生—临床医学]