16排CT对副鼻窦低剂量扫描的临床研究

Study of Effect on Image Quality in Low-dose CT of Paranasal Sinuses

目的：探讨16排CT对副鼻窦低剂量扫描的可行性,寻找合适的低剂量扫描条件。方法：从2008-01—2010-01,将210名来科检查的患者随机分4组（其他条件不变）：125mAs标准组29人、50mAs低剂量第1组95人、30mAs低剂量第2组62人、20mAs低剂量第3组24人。使用CTDIvol值评价各组受到的剂量。测量各组剂量、采用不同算法（软组织算法和骨算法）时图像的SD值,并对各组扫描图像的质量进行评价。评价指标：上颌窦开口、中鼻甲、下鼻甲、钩突、筛泡、筛漏斗。评价标准：清晰显示2分,显示但不清晰1分,未见显示0分。左右分别评分。对以上数据分别进行统计学分析。结果：扫描剂量加权指数（CTDIvol）与扫描剂量呈正性相关,1~3组患者所受剂量与标准组比较,剂量降低,有统计学意义（P〈0.05）。图像噪声SD值骨算法1组与标准组比较无统计学意义（P〉0.05）,软组织算法1~3组与标准组比较无统计学意义（P〉0.05）;图像质量评分1~3组与标准组差异无统计学意义（P〉0.05）。结论：单纯降低管电流条件,受检者所受剂量的减少有统计学意义,50mAs低剂量1组图像噪声及质量与标准组比较均无明显降低,能够满足诊断要求。选择合适的扫描条件,16排CT低剂量检查副鼻窦,完全可行。

Objective To determine the effect of reducing scanning dose on the diagnostic quality of images by accessory nasal sinus coronal CT, and seek for the proper scanning methods of low dose. Methods 210 patients were examined, who suffered the accessory nasal sinus disease, by using different scanning dose scanning sequence by chance, including 29 cases for 125 mAs, 95 cases for 50 mAs, 62 cases for 30 mAs, 24 cases for 20 mAs. CTDIvol was used to measure the dose in each group. SD quantity of images was measured under different scanning dose and different calculating methods as well as evaluate the quality of kinds of dose scanning images. Evaluating reference： maxillary ostium, middle turbinate, below turbinate, uncinate process, cribriform and ethmoid infundibulum. Evaluating standard： clearly demonstrated （2 points）; demonstrated but not clearly visualized （1 point）; not seen （0 point）. The left side was distinguished from the right and the data was analyzed in statistics. Results The CTDIvol value related to radiation dose when they turned out to be directly proportional. The statistics meaning existed when the scanning dose equaled or less than 50 mAs （P0.05）. The SD values had the statistics meanings under the high-resolution; 50mAs under t the soft arithmetic didn＇t have the statistics meanings, either（P0.05）; nor did the images quality of 50mAs, 30 mAs and 20 mAs（P0.05）. Conclusion The dose that the patients suffered decreases clearly only by lowering the mA. The noise and the quality of the scanning image remain the same when using the 50 mAs, which can satisfy the diagnosis demands. It is feasible to examine paranasal sinuses by using 16- slice CT in low dose under proper condition.