螺旋CT对塑料球并突起模型的成像观察  

The experimental observation of image quality of spiral CT in plastic ball phantom

作　　者：柳学国[1] 洪国斌[1] 王坚 王颖[1] 谈高[1] 李占军[1] 

机构地区：[1]珠海市医疗中心医学影像中心

出　　处：《中华放射学杂志》1998年第1期36-40,共5页Chinese Journal of Radiology

摘　　要：目的比较螺旋ＣＴ（ＳＣＴ）不同层厚及床速对塑料球及突起模型成像的还原准确性及多平面成像（ＭＰＲ）的影响。材料与方法自制塑料球（直径１５ｍｍ）上置２４根突起（长１、３、５ｍｍ，直径２ｍｍ），长短相间排列，并在其旁置不同走行方向的１ｍｍ和２．７ｍｍ导管若干根，模拟结节旁肺血管。层厚（ｍｍ）、每秒进床速度（ｍｍ／ｓ）、重建间隔（ｍｍ）分别以１０、１０、１ｍｍ，１０、１０、１ｍｍ，５、５、１ｍｍ，３、６、１ｍｍ，２、２、１ｍｍ，和高分辨率ＣＴ（ＨＲＣＴ）扫描，比较横断面及ＭＰＲ图像质量。结果各组扫描横断成像均能显示突起存在和数目，只是≤３、３、１ｍｍ时显示突起的位置和方向性及清晰度更优。床速≥５ｍｍ／ｓ时ＭＰＲ的球及突起明显拉长、模糊，不宜评价。螺距为０．５时采用１８０内插法（ｓｌｉｍ）对于提高ＭＰＲ质量是必要的。床速≥１０ｍｍ／ｓ时，横断面图像上紧邻突起、球或相互交叉的斜行导管可能被误解为有侵蚀。结论若要ＭＰＲ评价球灶、突起及周围导管更为精确，ＳＣＴ扫描参数应≤３、６、１ｍｍ，螺距＜１时重建内插算法务必采用１８０°内插算法。进床速为１０～２０ｍｍ／ｓ的ＳＣＴ可作为筛选病灶及初步定性的方法。Purpose Comparing the effect of different beam width and table speed on spiral CT image quality of transverse section and multiplanar reconstruction (MPR) in plastic ball phantom with projections. Materials and methods The phantom consisted of a plastic ball (1.5 cm) with 24 projections (1,3,5 mm long, 2 mm in diameter, 3 rows×8 projections). Some catheters of 3F (1 mm) and 7F (2.7 mm) were put on the phantom in different orientations in order to simulate pulmonary vessels. The scan parameters were (beam width/table speed/reconstruction interval, mm) 10、20、1, 10、10、1, 5、5、1, 3、61,3、3、1, and 2、2、1 in spiral CT. The images were compared in regard to quality of transversal sections and MPR on ball, projection and vessel. Results The identification and number of projection were displayed in each technique, but the position and orientation of projection were shown more accurately and clealy in ≤3、6、1 and a bit more noise in 10、20、1 or 10、10、1. The MPR of ball and projection was not siutable for evaluation in ≥5、5、1, because of obvious “tail like” artifact. It was nessesary to use slim (180°) interpolation for better MPR when pitch=1∶2[pitch=beam width(mm): table speed(mm/s). the oblique oriented vessel could be mis interpreted as being invaded in transverse section of ≥10、10、1. Conclusion The spiral CT with table speed of 10～20 mm/second was a method of screening and preliminary characterization. For accurate evaluation of MPR of ball, projection and vessels, the scan parameter must be less than 3、6、1. It was nessesary to use slim interpolation when pitch<1.

关 键 词：影像学诊断 CT 螺旋CT 塑料球 突起模型 

分 类 号：R814.42[医药卫生—影像医学与核医学]