论文部分内容阅读
目的本研究探讨使用热塑面罩固定的鼻咽癌患者,在治疗过程的摆位不确定度。方法选择首次放疔的早期鼻咽癌患者19例,仰卧体位,个体化泡沫头枕,热塑面膜固定,将等中心点置于鼻咽腔附近,由三维激光灯在而罩上定出左、中、右3个原始十字标志点,并贴上直径约为0．3 mm的铅珠作为显像标记,然后行CT扫描。将CT图像通过网络传到Peacock的逆向计划系统进行计划设计,然后实施治疗。在治疗的一至六周,每周在CT模拟机进行重复扫描,共85次,扫描及固定和摆位方法都与进行计划CT时相同。将每周验证体位重复性的CT图像与计划CT图像通过读图软件进行比较。结果通过对19例患者的85次重复CT与计划CT比较,得出使用本面罩系统时,等中心点的平均位置坐标为(-0．84,+0．65,+0．01)mm；不同解剖骨性标记点在x、y、z 3个轴向的绝对位移值分别为(0．89±0．69),(0．82±0．79),(0．95±1．24)mm；等中心点三维矢量位移的平均值为1．87mm；等中心点三维矢量位移的95%可信区间(CI)最大值7．24mm,最小值2．03mm,平均值3．82mm；第一周到第三周等中心点二维矢量位移95%CI的平均值是4．17mm,第四周到第六周的平均值是5．12mm。结论使用连续CT多次重复扫描的方法来研究鼻咽癌治疗过程中的摆位不确定度是可行的。
OBJECTIVE: This study explored the uncertainty of the positioning of patients with nasopharyngeal carcinoma using a thermoplastic mask. Methods Nineteen patients with early nasopharyngeal carcinoma were selected for the first time. Supine position, individualized head foam and thermoplastic mask were fixed. The isocenter was placed near the nasopharyngeal cavity, , The middle and the right of the three original cross mark points, and paste the diameter of about 0.3 mm lead as the imaging mark, and then line CT scan. The CT images were sent to Peacock’s reverse planning system through the internet for planning and planning and then treatment. One week to six weeks of treatment, CT scans were repeated weekly for a total of 85 scans, and the fixation and placement procedures were the same as for planned CT. Weekly verification of position-repeat CT images and planning CT images were compared using chart reading software. Results The average position coordinates of isocenters were (-0.84, +0.65, +0.01) mm when using this mask system compared with planned CT in 85 cases of 19 patients. The absolute displacements in three axial directions of x, y and z were (0.89 ± 0.69), (0.82 ± 0.79) and (0.95 ± 1.24 ) mm; the average value of the three-dimensional vector displacements at isocenter is 1.87mm; the 95% confidence interval (CI) maximum is 7.24mm, the minimum is 2.03mm and the average is 3.82mm; From the first week to the third week, the average 95% CI of the two-dimensional vector displacements at the isocenter is 4.17 mm, and the average value from the fourth week to the sixth week is 5.12 mm. Conclusion It is feasible to study the setup uncertainty of nasopharyngeal carcinoma by using the method of continuous CT multiple repeat scan.