目的 探讨上气道CT检查中使用管电流调制技术降低辐射剂量的可行性.方法 在管电流调制技术发展的三个阶段各选取33例成人上气道CT检查病例,共3组99例:常规剂量组,预设管电流量250 mAs;推荐剂量(Doseright)组,使用系统根据定位像和扫描范围推荐的有效mAs;Z轴管电流调制(Z-DOM)组,系统根据定位像在人体Z轴方向自动调节管电流.前两组扫描过程中mA保持不变,Z-DOM组mA改变;其他参数相同.用3mm层厚重组正中矢状面图像,测算对比噪声比(CNR);并用5分法对正中矢状面图像质量进行主观评价.对各组辐射剂量指标CT剂量指数(CTDI)、剂量长度乘积(DLP)和主客观评价指标进行统计学分析.结果 三组的CTDI分别为:(14.70±0.00) mGy、(16.50±2.59) mGy、(4.60±1.99) mGy,DLP分别为(465.87 ±31.55) mGy· cm、(526.15±98.28) mGy·cm、(147.74±67.08) mGy·cm,辐射剂量差异有统计学意义(CTDI和DLP的F值分别为381.24和270.08,P＜0.05),Doseright组的剂量高于常规剂量组10％,Z-DOM组明显低于前两组,分别为常规齐量组的30％、Doseright组的25％;三组CNR分别为523.91±80.75、540.28±117.65、511.09±107.56,差异无统计学意义(F =0.603,P=0.549 ＞0.05);三组的主观评价指标分别为10.5(10,11.5)、11(10.5,11.5)、12.5(12.25,13.0),差异有统计学意义(x2=48.373,P＜0.05),两两比较Doseright组略高于常规剂量组(x2=0.038,P＞0.017),差异无统计学意义,Z-DOM组高于常规剂量组和Doseright组(x2值分别为36.972和35.601,P＜0.017),差异有统计学意义. 结论 上气道CT检查使用Z-DOM技术可有效降低辐射剂量,且保持较高的图像质量,可在临床实践中推广应用.“,”Objective To investigate the feasibility of using tube current modulation technique to reduce the radiation dose in CT examination of upper respiratory tract.Methods A total of 99 adult patients were enrolled in this study.The patients were randomly and equally divided into three groups with 33 cases in each group.CT scanning of upper respiratory tract was performed in all patients.In the conventional dose group (group A) the preset effective mAs was 250 mAs/slice,in the Doseright group (group B) the recommended mAs (according to the surview and scanning range) was employed,while in the Z-DOM group (Z axis tube current modulation,group C) the tube current was automatically adjusted by the system according to the positioning in the Z axis direction.During the scanning course the mA value was kept stable in group A and group B,while the mA value was changing in group C; the other parameters used in all three groups were the same.All the images were reconstructed by filtered back projection (FBP) algorithm.The median sagittal images were reformatted with 3 mm thickness,and their corresponding contrast-to-noise ratios (CNR) were calculated; the median sagittal images were subjectively evaluated by five division method (subjective evaluation score).The values of CTDI,CNR,DLP and subjective evaluation score of three groups were statistically analyzed.Results For group A,B and C,the CTDI was (14.70 ± 0.00) mGy,(16.50 ± 2.59) mGy and (4.60 ± 1.99) mGy respectively ; the DLP was (465.87 ± 31.55) mGy · cm,(526.15 ±98.28) mGy · cm and (147.74 ±67.08) mGy · cm respectively; and the differences in radiation doses between each other among the three groups were statistically significant (the F values of CTDI and DLP were 381.24 and 381.24 respectively,P ＜ 0.05).The radiation dose of group B was 10％ higher than that of group A,the dose of group C was significantly lower than that of group A and group B:about 70％ lower than that of group B and 75％ lower than that of group A.The CNR of group A,B and C was 523.91 ± 80.75,540.28 ± 117.65 and 511.09 ± 107.56 respectively,and the differences in CNR between each other among the three groups were statistically significant (F =0.603,P =0.549 ＞ 0.05).The subjective evaluation scores of group A,B and C were 10.5 (10,11.5),11(10.5,11.5) and 12.5 (12.25,13.0) respectively,and the differences in subjective evaluation score between each other among the three groups were statistically significant (chi-square =48.373,P ＜ 0.05):the subjective evaluation score of group B was slightly higher than that of group A (chi-square =0.038,P ＞0.017),the subjective evaluation score of group C was higher than that of group A and group B (chi-square values were 36.972 and 36.972 respectively,P ＜ 0.017).Conclusion The use of Z-DOM technique in CT examination of upper respiratory tract can effectively reduce the radiation dose while higher image quality can be reliably preserved.Therefore,this technique should be recommended in clinical practice.