鼻咽癌调强放疗中不确定因素的临床研究

发布时间：2018-01-17 20:03

本文关键词：鼻咽癌调强放疗中不确定因素的临床研究　出处：《济南大学》2013年硕士论文　论文类型：学位论文

【摘要】：目的：鼻咽癌患者调强放疗过程中许多不确定性因素将降低放疗计划的优越性，以往大多数研究仅关注其中某一方面，本文研究放疗过程中在靶区勾画、摆位误差及器官运动方面存在的不确定性以更好的指导临床计划靶区及计划危及器官体积的确定，指导临床进行二次计划修改的最佳时机。方法：选取我院2011年11月-2012年7月首诊经病理学证实的鼻咽癌患者10例，获取其计划CT图像及放疗过程中第1-5周每周重复CT扫描图像。2位医师和1位影像医师分别勾画双侧腮腺、颌下腺和脊髓，研究不同勾画者间的勾画差异。将计划CT图像与每周重复CT图像融合，于计划系统内建立空间坐标系选取参考点观察放疗过程中每周摆位位移情况，计算摆位系统误差及摆位随机误差，进而得出计划靶区外扩范围，于计划CT和每周重复CT上逐层勾画腮腺外轮廓，于计划系统内计算每周腮腺体积、位移及实际受照剂量的变化情况，观察三者变化最显著时刻，并根据患者每周双侧腮腺空间中心点空间三维方向位移变化情况确定双侧腮腺计划危及器官体积，随访患者放疗结束后3个月口腔干燥程度并计算其与腮腺体积及实际受照剂量之间的相关性大小。结果：脊髓勾画差异最小为2.7%～4.3%，双侧颌下腺勾画差异最显著分别是5.5%～7.6%和-4.1%～6.2%，双侧腮腺勾画差异居中分别为-2.3%～5.6%和-1.4%～3.8%。侧向、上下、前后方向摆位位移分别为（0.93±0.71）mm、（1.12±0.84）mm、（1.21±1.12）mm，摆位系统误差及摆位随机误差于空间三维方向均2mm，4.5-5mmPTV边界即足够。双侧腮腺放疗5周后体积分别较放疗前缩小29%-44.9%和28%-57.1%，双侧腮腺剂量分别为放疗前的148.3%-259.4%和198.1%-274.7%，双侧腮腺中心点于三维方向位移分别为（3.86±3.39）、（4.15±2.17）、（2.89±2.84）；（3.56±2.18）、（3.83±2.96）、（3.25±2.96）。左侧腮腺体积、侧向位移及剂量均于放疗第3周变化最显著，右侧腮腺体积、侧向位移及剂量分别于放疗第4周、第2周和第3周变化最显著，且三者均为放疗过程中前3周的变化幅度大于放疗过程中后2周的变化幅度。患侧腮腺位移变化所致系统误差最大为2.19mm，健侧腮腺位移变化所致系统误差最大为2.23mm。理论上，腮腺计划危及器官体积应为6.5mm，尤其是健侧腮腺。放疗3个月后患者多为轻中度口干，无重度口干发生，其与腮腺体积、剂量变化间有明显相关性。结论：鼻咽癌患者调强放疗过程中，，应注意众多不确定因素对放疗计划实施的影响，减少靶区及危及器官的勾画差异，外扩一定计划靶体积危及器官体积将会有更好的临床获益，在放疗过程中第3周修改放射治疗计划将使腮腺实际受照剂量进一步降低。
[Abstract]:Objective: many uncertain factors in intensity modulated radiotherapy (IMRT) in nasopharyngeal carcinoma (NPC) patients will reduce the superiority of radiotherapy plan. The uncertainty of pendulum error and organ movement can better guide the target area of clinical planning and the determination of organ volume and the best time to modify the second plan. Methods: ten patients with nasopharyngeal carcinoma confirmed by pathology from November 2011 to July 2012 in our hospital were selected. During the 1-5 weeks, 2 doctors and 1 imager drew bilateral parotid gland, submandibular gland and spinal cord respectively. To study the difference of drawing between different sketchers, combine the planned CT images with the weekly repeated CT images, and set up the reference points in the planning system to select the reference points to observe the weekly displacement during radiotherapy. The systematic error of pendulum and random error of pendulum were calculated, and then the expanding range of planning target area was obtained. The outline of parotid gland was drawn layer by layer on plan CT and repeated CT every week, and the volume of parotid gland per week was calculated in planning system. The changes of displacement and actual radiation dose were observed and the most significant changes were observed. According to the change of three-dimensional displacement of the center space of bilateral parotid gland every week, the volume of organ was determined by the plan of bilateral parotid gland. The degree of oral dryness was calculated 3 months after radiotherapy and the correlation with the volume of parotid gland and the actual dose of irradiation was calculated. Results: the minimum difference of spinal cord delineation was 2.7% and 4.3.The most significant difference in bilateral submandibular gland was 5.6% and -4.1%, respectively. The difference between bilateral parotid gland drawing and parotid gland drawing was -2.3% and -1.4%, respectively. The displacement of lateral, upper-down and anteroposterior directions was 0.93 卤0.71 mm. The systematic error and random error of the pendulum were all 2mm in three dimensional direction, and 1.12 卤1.12 卤1.21 卤1.12 卤1.12 卤0.84 卤0.84 卤0.84 卤0.84 卤0.84 卤0.84 卤0.84 卤0.84 mm respectively. The volume of bilateral parotid gland decreased by 29% -44.9% and 28-57.1% respectively after 5 weeks of radiotherapy. The dosages of bilateral parotid gland were 148.3% -259.4% and 198.1%, respectively. The displacement of the central point of bilateral parotid gland in three dimensional direction was 3.86 卤3.39). 4.15 卤2.17, 2.89 卤2.84; The volume, lateral displacement and dose of the left parotid gland were the most significant at the 3rd week of radiotherapy, and the volume of the right parotid gland was the most significant. Lateral displacement and dose showed the most significant changes at week 4, week 2 and week 3, respectively. The range of change in the first three weeks of radiotherapy was greater than that in the second week of radiotherapy. The maximum systematic error caused by the change of parotid gland displacement in the affected side was 2.19 mm. The maximum systematic error caused by the displacement of the healthy parotid gland was 2.23mm. theoretically, the organ volume of the parotid gland planned to endanger should be 6.5mm, especially the healthy parotid gland. After 3 months of radiotherapy, the majority of patients were mild to moderate dry mouth. There was no severe xerostomy, and there was a significant correlation between the volume and dose of parotid gland. Conclusion: in the course of intensity-modulated radiotherapy for nasopharyngeal carcinoma patients, we should pay attention to the influence of many uncertain factors on the implementation of radiotherapy plan, and reduce the difference of target area and dangerous organs. The external expansion of target volume will have a better clinical benefit to the organ volume, and the modification of the radiotherapy plan in the third week of radiotherapy will further reduce the actual radiation dose of the parotid gland.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：R739.63

【参考文献】