双源 CT 大螺距扫描模式在儿童胸部低剂量成像中的应用价值

目的：探讨双源C T 大螺距扫描模式在儿童胸部成像中的辐射剂量及图像质量的应用价值。方法将80例行双源C T胸部检查的患儿随机分为A、B两组。其中A组40例，行大螺距模式扫描，螺距3.0；B组40例，行常规模式扫描，螺距1.2。对A、B两组图像质量、辐射剂量（CT容积剂量指数CTDIvol值、剂量长度乘积DLP值及有效剂量 E）及扫描时间进行对比分析。结果 A、B两组均获得了满足临床诊断的图像，图像质量差异无统计学意义（Z＝－1.75，P＝0.08）；A、B两组患儿的CTDIvol值分别平均为1.82 mGy、4.50 mGy ，差异具有统计学意义（t＝－32.50，P＝0．00），A组患儿较B组患儿下降59.56％。A、B两组患儿的DLP值分别平均为38.41 mGy／cm、82.74 mGy／cm ，差异具有统计学意义（t＝－37.94，P＝0.00）， A组患儿的DLP值较B组患儿下降53.58％。A组患儿的平均扫描时间（0.27 s）明显短于B组患儿（2.60 s），差异有统计学意义（t＝41.31，P＝0.00），A组扫描时间仅为B组的10.38％。结论双源CT 大螺距扫描模式具有扫描速度快、辐射剂量低等优点，在儿童胸部低剂量扫描中具有重要价值。

The application value of low-dose of high-pitch scan mode of dual-source computed tomography in the chest of children

Objective To evaluate the radiation dose and image quality of the application of high‐pitch scan mode of dual -source computed tomography in the chest of children .Methods 80 sick children who were going to do chest CT examination by dual‐source CT system were randomly divided into two groups of A B .40 children of group A were examined with a in high‐pitch scan mode(pitch=3.0);40 patients of group B were examined with in conventional pitch mode(pitch=1.2) .The image quality ,radiation dose(CTDIvol ,DLP) and scaning time between the two groups were analysed .Results The Image quality of group A and B meet the requirements of the clinical diagnosis .There is no significant difference in the image quality of group A and B(Z= -1.75 ,P=0.08);The average CTDIvol value of group A and B was 1.82 mGy、4.50 mGy .The CTDIvol value of group A was less than group B(t= -32.5 ,P=0.00) .The CTDIvol value of group A was decreased by 59.56% than group B . The average DLP value of group A and B was 38.41 mGy、82.74 mGy/cm .The average DLP value of group A and B was 38.41 mGy、82.74 mGy .The DLP value of group A was less than group B(t= -37.94 ,P=0.00) .The DLPl value of group A was decreased by 53.58% than group B .The scanning time of group A(0.27 s) was shorter than group B(2.60 s) (t=41.00 ,P=0.00) .The scanning time of group A(0.27 s) was less than group B(2.60 s)(t=41.34 ,P=0.00) .The scanning time of group A was accounted for only 10.38% of group B .Conclusion The high‐pitch scan mode of dual‐source computed tomography has higher scanning speed ,lower radiation dose in the chest ,there is important value in the loe‐dose scanning of children's chest .