CT窗技术变化对模拟肺结节大小测量的影响

The effect on Diameter of Simulated Pulmonary Nodules in Different CT Window Technique

目的研究不同窗技术对模拟肺部小结节大小测量的影响趋势。方法对10mm、20mm、30mm由鲜猪瘦肉制成的模拟肺结节进行螺旋扫描,层厚3mm,1.2mm重建。分别采用多个层级固定窗位后变换窗宽、固定窗宽后变换窗位两个系列,测量模拟肺结节中心层面横径,将每组测量结果中最接近结节真实大小的窗宽、窗位视为模拟肺结节的适宜窗口组合。结果每个适宜窗口组合对不同大小模拟结节测量结果的影响程度和趋势性基本一致。窗位对模拟结节大小测量的影响程度远大于窗宽的影响。不同层级窗位上,都对应一个比较适宜测量的窗宽,反之亦然。鉴于模拟结节平均CT值为70HU,则测量结节大小的最适宜窗口范围为窗位40～100HU、窗宽600～900HU。结论显示模拟肺结节真实大小的窗宽、窗位之间存在相互匹配和相对恒定的关系,窗宽700±200HU左右、窗位70±30HU为模拟肺结节测量的首选适宜窗口。

Objective To study the effect on the size of small simulated pulmonary nodules at CT measurement with different window techniques. Methods Three simulated pulmonary nodules（10mm,20mm,30mm） made from fresh pork were scanned by multi-slice spiral CT with the slice thickness of 3mm for scan and 1.2iron for reconstruction,and each diameter in the central dimension of the nodule was measured in the different window.The multiple combinations were used for the change between WW and WL in where the measurement results were closest to the real size of the nodules was considered as a appropriate Window combination. Results The extent of the impact to the measurement results of three nodules was similar in the each appropriate window combination.WL was the main factor to influence the size of the nodule, while WW had little effect. Corresponding with the different WL, there was a appropriate WW, and vice versa.For the average CT value（70HU） of the nodules, the most suitable whldow range was WL 40- 100HU and WW 600-900HU for measuring the nodule size. Conclusion There was the matching and fixed relationship between WW and WL for displaying the real size of the nodules.The scope of the preferred combination for CT measurement of the simulated pulmonary was WW 700 ± 200HU and WL 70 ± 30HU.