摘要
目的通过阶梯式扫描协议探寻头颈部CTA的优化扫描剂量。方法连续选择临床怀疑头颈部血管病变并行256层CTA检查的269例患者,从200 mA s原始条件开始,按检查时间顺序分别采用10 mA s阶梯式降低管电流量扫描至130 mA s共8组,分别测量并评估各组患者图像的背景软组织噪声(CT值的标准差)、目标血管的信噪比(SNR)、对比噪声比(CNR)、图像质量评分以及射线剂量指标[CT剂量指数(CTDI)、剂量长度乘积(DLP)、有效剂量(ED)]。采用统计学检验评价各组间的差异。结果实验总共历时8周,于130 mA s触发实验终止条件,并返回至140 mA s。随管电流阶梯式调整,辐射剂量线性下降,按周次顺序CTDI分别为13.50、12.84、12.18、11.49、10.80、10.12、9.44 mG y,有效剂量ED平均值分别为4.39、4.21、3.97、3.75、3.49、3.29、3.09 mS v。其中第7周140 mA s管电流量组的CTDI、DLP、ED平均值最低,分别为:CTDIVol 9.44 mG y,DLP 423.42 mG y/cm,ED 3.09mS v,较基础条件200 mA s相比,剂量降低比例达30%,各组患者射线剂量指标CTDI、DLP、ED之间的差异均有统计学意义(P<0.05);各组患者的目标血管SNR、血管-背景CNR之间的差异无统计学意义(P>0.05)。结论阶梯式参数优化方法可以科学、有效的摸索出扫描剂量与图像质量的最佳平衡点,优化现有设备的合理低剂量扫描;以本单位为例,256层CT头颈部血管成像检查,采用9.44 mG y扫描剂量(140 mA s管电流)既可满足临床诊断要求,又能降低受检群体接受的辐射剂量。
Objective To explorer and optimize the dose of cerebral＆carotid CT angiography imaging by staged protocols. Methods Continuous patients with clinically-suspected cerebral vascular diseases were enrolled and performed staged tube current scanning start from original 200 mA s to 130 mA s with 10 mA s decrease weekly,The background soft tissue and Target vascular segments were evaluated including Noise（ SD） 、SNR、CNR、Image quality Score as well as the CTDI、DLP and ED. Results The experiment lasted for 8 weeks and enrolled 269 patients totally; 130 mA s triggered the termination of the experiment and return to 140 mA s. With the tube current adjustment,the radiation dose decreased linearly,according to time sequence the CTDI is 13. 50,12. 84,12. 18,11. 49,10. 80,10. 12,9. 44 mG y respectively,the effective dose average 4. 39,4. 21,3. 97,3. 75,349,3. 29,3. 09 mS v respectively. The 140 mA s tube current group have the lowest CTDI,DLP and ED. respectively： CTDIVol 9. 44 mG y,DLP 423. 42 mG y / cm,ED 3. 09 mS v. compared to the original conditions 200 mA s,dose reduced 30%. The CTDI,DLP,ED were statistically lower than that of original group（ P 〈0. 05）; while the value of target vessel SNR,target vessel-background CNR have no statistically significant different（ P 〉0. 05）. Conclusion The staged protocols systematically optimize the system parameter gradually can easily find the best point between radiation dose and image quality,it’s a feasible method and has high clinical value for patient dose management. In this study 256-slice CT carotid and cerebral CT angiography,9. 44 mG y scanning dose（ 140 mA s） can meet clinical diagnosis requirement while greatly reduce the radiation dose by 30%.
出处
《临床放射学杂志》
CSCD
北大核心
2015年第8期1297-1301,共5页
Journal of Clinical Radiology
