锥形束CT在精确放射治疗摆位中的应用研究

发布时间：2018-03-04 15:13

本文选题：机载影像系统OBI　切入点：锥形束CT　出处：《青岛大学》2017年硕士论文　论文类型：学位论文

【摘要】：目的:应用瓦里安直线加速器的机载影像系统(on board imager,OBI)的二维正侧位拍片模式和三维锥形束CT(cone beam computed tomography,CBCT)模式分别分析头颈部、体部及盆腔肿瘤在精确放射治疗中的摆位误差,对比这两种模式验证在首次验证时人体各部位的定位精度,探讨人体不同部位肿瘤摆位验证工作中,两者的优缺点,为指导临床工作中不同部位选取哪种模式获益最大提供可靠依据。方法:应用VarianClinaciX医用直线加速器的机载影像验证系统,对我科精确放射治疗的60例病人做对比研究,头颈部、体部、盆腔部各20例。全部病人均采用热塑料体(面、头颈肩)模固定,行CT模拟定位,贴金属标记点、扫描CT图像传至计划系统,经医生勾画肿瘤靶区,物理师进行个体化计划设计,每个计划包含OBI正侧位平片摆位野和CBCT摆位野,首次治疗前复位移至等中心点,分别采集DR正侧位片和CBCT图像,分别与计划系统所生成的DRR图像和定位时CT图像进行2D/2D match和3Dmatch,采用自动匹配分析对比两组摆位误差,病人左右方向位移记为X,头脚方向记为Y,前后方向记为Z,分别记录三维方向线性位移大小。结果:用误差总体的均数描述摆位误差的平均值,记为系统误差,用误差总体的标准差描述所有分次的摆位误差的标准差,记为随机误差,X轴(左右)、Y轴(头脚)、Z轴(前后)的误差最终用系统误差±随机误差表示,即用x±s表示。首次治疗前二维OBI模式拍片验证所得头颈部肿瘤摆位误差为X:0.14±0.06cm、Y:0.27±0.09cm、Z:0.16±0.05cm,体部摆位误差为 X:0.31±0.09cm、Y:0.59±0.19cm、Z:0.27±0.08cm;盆腔摆位误差X:0.31±0.09cm、Y:0.53±0.15cm、Z:0.26±0.09cm;三维CBCT模式验证所得头颈部摆位误差X:0.13±0.05cm、Y:0.25±0.09cm、Z:0.15±0.06cm,体部摆位误差为 X:0.240±0.05cm、Y:0.44±0.16cm、Z:0.21±0.06cm,盆腔病人摆位误差 X:0.20±0.07cm、Y:0.38±0.12cm、Z:0.18±0.08cm;所有数据均采用Microsoft Excel进行录入并做简单作图分析,用SPSS21.0统计软件进行统计分析,对两种模式分别在X、Y、Z轴上进行定量资料独立t检验,头颈部在三个方向的差异无统计学意义(p0.05),体部和盆腔病人在三个方向的差异均有统计学意义(p0.05)。结论:可以看出两种模式验证在头颈部摆位验证时差异没有统计学意义,均能满足精确放射治疗对摆位验证的要求,具有相同的趋势,最大误差均出现在头脚方向Y轴,这可能与CT扫描造成的系统误差有关;而在体部盆腔患者,两种模式验证差异有统计学意义,表明在人体受呼吸运动、肠蠕动及膀胱充盈大小等影响较大的部位CBCT验证优势明显,更能实时验证肿瘤靶区大小及形状的变化以及周围危及器官的位移大小,防止靶区漏照或者正常组织接受高剂量照射,在临床上更具指导意义。
[Abstract]:Objective: to analyze the positioning errors of head and neck, body and pelvic tumors in accurate radiotherapy by using the two dimensional positive and lateral mode and the three dimensional conical beam CT(cone beam computed tomographyCBCT mode of Varian linear accelerator's airborne imaging system (OBI). Comparing the positioning accuracy of each part of human body during the first verification, and discussing the advantages and disadvantages of the two modes in the verification of tumor pendulum in different parts of human body. In order to guide the clinical work to choose which mode to benefit the most in clinical work. Methods: using the airborne image verification system of VarianClinaciX medical linear accelerator, 60 patients who received accurate radiotherapy in our department were studied, head and neck, head, neck, head, neck, head, neck, head, neck, head, neck, head, neck, head and neck, All the patients were fixed with thermoplastic body (face, head, neck and shoulder), were imitated by CT, attached metal marks, scanned CT images were transmitted to the planning system, and the tumor target area was drawn by doctors. The physicist designed the individual plan. Each plan consisted of the OBI positive and lateral plain film pendulum field and the CBCT pendulum field. Before the first treatment, the reposition moved to the isocentric point, and the Dr positive and lateral images and CBCT images were collected, respectively. 2D / 2D match and 3D matchup were performed with the DRR images generated by the planning system and CT images respectively, and the two groups of pendulum errors were compared by automatic matching analysis. The patient's left and right direction displacement is recorded as X, head and foot direction as Y, front and rear direction as Z, three dimensional direction linear displacement is recorded separately. Results: the mean of the total error is used to describe the mean value of the pendulum error, and the system error is recorded. The standard deviation of the error population is used to describe the standard deviation of the pendulum error of all grades, which is recorded as the random error and the error of the X axis (left and right / right / right / Y axis) is finally expressed as the system error 卤random error. The error of head and neck pendulum was: X: 0.14 卤0.06 cm Y: 0.27 卤0.09 cm Z: 0.16 卤0.05 cm, X: 0.31 卤0.09 cm Y: 0.59 卤0.19 cm Z: 0.27 卤0.19 cm Z: 0.27 卤0.08 cm; pelvic position error X: 0.31 卤0.09 cm Y: 0.53 卤0.15 cm ~ (-1) Z: 0.26 卤0.09 cm; error of head and neck pendulum: X: 0.13 卤0.05 cm ~ (0.05) cm Y: 0.25 卤0.09 cm, body position error: X: 0.31 卤0.09 cm: YW: 0.26 卤0.09 cm; error of head and neck pendulum: X = 0.13 卤0.05 cm ~ 0. 05 cm Y: 0.25 卤0.09 cm. The error is: X: 0.240 卤0.05cm, Y: 0.44 卤0.16cm, Z: 0.21 卤0.06cm, X: 0.20 卤0.07cm, Y: 0.38 卤0.12cm / Z: 0.18 卤0.08cm; all data are recorded and analyzed by Microsoft Excel. The statistical analysis was carried out with SPSS21.0 software, and the independent t test of quantitative data was carried out on the XG YZ axis of the two models, respectively. There was no significant difference between head and neck in three directions, but there was no significant difference between body and pelvic patients in the three directions. Conclusion: it can be seen that there is no significant difference between the two modes in head and neck pendulum. All of them can meet the requirements of accurate radiotherapy for pendulum verification and have the same trend. The maximum errors appear in the Y axis of the head and foot direction, which may be related to the systematic errors caused by CT scan, while in patients with pelvic cavity in the body, The difference between the two models was statistically significant. The results showed that CBCT had obvious advantages in the parts of human body affected by respiratory movement, intestinal peristalsis and bladder filling size, etc. It can be used to verify the changes of tumor target size and shape and the displacement of the surrounding organs in real time, and to prevent the target area from leaking or the normal tissue to receive high dose irradiation, which is more instructive in clinical practice.
【学位授予单位】：青岛大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R730.55

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