新生儿头颅多层螺旋CT低剂量扫描的临床应用

目的：评价新生儿头颅多层螺旋CT低剂量扫描的临床价值。方法：选取头颅CT检查的新生儿80例，随机等分成2组，分别使用120kV、90mAs及120kV、260mAs各扫描40例。其余扫描参数为：准直1．5mm，层厚6mm，重建间隔6mm，床速11．7mm／r，扫描时间0．75s。分别比较2种扫描剂量产生的总mAs、CT权重剂量指数（CTDIw）及剂量长度乘积（DLP），并作t检验。由3名医师采用盲法评价CT图像。按正常图像、图像有少许伪影、图像有严重伪影的等级对每帧图像进行质量评价，并进行统计学处理。结果：90mAs、260mAs组扫描的CTDIw分别为17．28mGy、49．85mGy，DPL分别为245mGy·cm、711mGy·cm。经t检验，90mAs组的CTDIw、DLP明显低于260mAs组（P〈0．01）。满足诊断需要的低剂量扫描图像所占比例（98．6％）与常规剂量扫描（99．9％）相比无显著差异（P〉0．05）。结论：新生儿头颅多层螺旋CT低剂量扫描的辐射剂量为常规剂量扫描的35％，而且图像不影响诊断，低剂量扫描适用于新生儿头颅CT检查。

Clinical Application of Low-dose Multi-slice Spiral CT Scanning for Neonate Brain

Objective： To assess the clinical value of multi slice spiral CT （MSCT） low dose scanning for neonate brain. Methods：80 newborns going to take cerebral CT were randomly assigned into two groups, including low dose group （120kV.90mAs） and standard dose group （120kV.260mAs） ,with 40 cases for each group. The other scanning parameters including scanning time,0.75s; collimation, 1.5mm; thickness, 6mm; interval, 6mm; table speed 11.7mm/r were the same. The weighted CT dose index （CTDIw） ,dose length product （DLP） and total mAs produced by two scanning protocols were measured and compared respectively,t test was performed. CT images were evaluated by three doctors using blind method. The image quality was evaluated according to 3 grades：normal image,image with mild artifact, and image with serious arti- fact and the results were analyzed statistically. Results： The CTDIw was 17. 28mGy for 90mAs group, 49. 85mGy for 260mAs group. DPL was 245mGy · cm for 90mAs group,711 mGy · cm for 260mAs group. The CTDIw and DLP of low dose group were lower than that of standard dose group （P〈0.01）. 98.6% of the image quality of low dose group could meet the standard of diagnosis, which showed no significant statistical difference with that of standard dose group （99.9 %, P〉0.05）. Conclusion：The radiation dose produced by low dose MSCT was 35 % of that produced by standard dose in neonate cerebral CT examination. The image quality of low dose CT could meet the needs of diagnosis,so it is applicable in CT examination of neonate brain.