超低管电压（70 kVp）联合FLASH技术在儿童鼻旁窦CT中的应用

目的 探讨双源CT超低管电压（70 kVp）联合FLASH的扫描技术在儿童鼻旁窦检查中的可行性。方法 选取80例临床怀疑鼻旁窦炎的患儿随机分成A、B两组，实验组（A组） 40例：管电压70 kVp，螺距3.0，所得数据采用迭代算法（SAFIRE） 重建；对照组（B组）40例：管电压80 kVp，螺距1.5，所得数据采用滤波反投影算法（FBP）重建。分析比较2组不同扫描方式的主、客观图像质量以及辐射剂量，包括容积CT剂量指数（CTDIvol）、剂量长度乘积（DLP），并计算有效辐射剂量（ED）。结果 患者所受的辐射剂量，实验组的CTDIvol （mGy）、DLP （mGycm）和ED （mSv）较对照组显著降低（CTDIvol：0.39 ±0.004 vs 1.57 ±0.009 mGy，P < 0.001；DLP：6.31 ±0.52 vs 19.88 ±2.01 mGycm，P < 0.001；ED：0.024 ±0.005 vs 0.079 ±0.016 mSv，P < 0.001）。较对照组，试验组的图像噪声及SNR_硬组织均有所增加，SNR_软组织则有所下降。2名医师对2组图像质量的主观评分无统计学差异（P ＞0.05）。结论 超低管电压（70 kVp）联合FLASH扫描技术可明显降低儿童鼻旁窦CT扫描剂量，且图像质量均满足诊断要求。

Application of 70 kVp tube voltage combined with the FLASH in low-dose CT of pediatric paranasal sinus

Objective To evaluate the feasibility of dual-source low-dose computed tomography (CT) of the paranasal sinus in children, with acquisition at an ultra-low tube voltage (70 kVp) combined with the Flash scan.Methods CT scans of the paranasal sinus were performed on 80 pediatric patients who were divided into two groups according to different protocols (70 kVp protocol with Flash scan mode and the iterative reconstruction, pitch 3, the experimental group (group A), n = 40; 80 kVp protocol with conventional spiral mode, pitch 1.5, control group (group B), n = 40). For each examination, the CT dose index (CTDIvol), dose-length product (DLP) and effective dose (ED) were estimated. The image noise, signal-to-noise ratio (SNR) and overall subjective diagnostic image quality were also evaluated.Results The images of these two groups were all satisfied for the clinical diagnosis. For radiation dose, the CTDIvol (mGy), DLP (mGycm) and ED (mSv) values of the 70 kVp protocol were significantly lower than those of the 80 kVp protocol [CTDIvol: 0.39 ±0.004 vs1.57 ±0.009 mGy, P < 0.001; DLP: 6.31 ±0.52 vs 19.88 ±2.01 mGycm, P < 0.001; ED: 0.024 ±0.005 vs 0.079 ±0.016 mSv, P < 0.001. Compared with those of the 80-kVp protocol, the image noise and the SNR_bone increased, the SNR_soft-tissue decreased. There was no statistical difference in the subjective scores of the two groups of image quality by the two physicians (P > 0.05).Conclusion When diagnosing the paranasal sinus in children, an ultralow tube voltage (70 kVp) combined with the Flash scan technique can reduce the radiation dose significantly while maintaining diagnostic image quality with clinically acceptable image noise.