不同放疗定位CT扫描条件对气管支架图像质量影响的研究

Study on Effects of CT Image Quality Which Contain Tracheal Stent Under Different Scanning Conditions in Radiotherapy Simulation Positioning

目的比较不同扫描条件下气管支架的定位CT图像,探讨适合含有气管支架的放疗病人的模拟定位CT扫描条件。方法将气管支架放入自制的泡沫管套中,一起放入非均匀模体中进行CT定位扫描,扫描条件为80kV/120mAs、120kV/80mAs、120kV/120mAs,扫描方式为轴向扫描和螺旋扫描,扫描层厚分别为0.6、1、2、3mm,扫描完成后传到治疗计划系统,两名有经验的放疗科医生对各组图像进行评分,使用Matlab8.3数据处理软件读取各组图像同一层面支架的CT值。结果相同条件下轴向扫描比螺旋扫描图像更清晰;扫描层厚越小,图像伪影越少,图像越清晰;管电流对支架CT值没有影响,管电压越小,支架CT值越大。结论在条件允许情况下,含有气管支架的肿瘤病人放疗CT定位时扫描方式选择螺旋扫描,扫描层厚选择1mm,选择固定的管电压。

Objective To evaluate the tumor localization CT scan conditions suitable for patients with tracheal stent,by comparing the CT images of tracheal stents under different scanning conditions.Methods The tracheal stent was placed in a self-made foamed tube,with which the stent was then placed in a non-homogeneous phantom for CT positioning scanning.The scanning conditions were 80 kV/120 mAs,120 kV/80 mAs,120 kV/120 mAs,and the scanning methods were axial scanning and helical scanning.The slice thickness of scanning were 0.6,1,2 and 3 mm.After the scanning,the images were sent to the treatment planning system.Two experienced radiologists rated the images for each group.CT values of the tracheal stent at the same level in each group of images were read using Matlab 8.3 data processing software.Results Under the same condition,the axial scan is clearer than the spiral scan.The smaller the scanning slice thickness,the less the artifacts and the clearer the image.The tube current had no effect on the CT value of the stent.The smaller the tube voltage,the larger the CT value of the stent.Conclusion In the radiotherapy CT localization of tumor patients with tracheal stent,spiral scan should be selected as the scanning mode,the slice thickness of scanning should be 1 mm,and the fixed tube voltage should be selected.