螺距优化组合对胸腹部CTA图像质量与辐射剂量探讨

Pitch Optimizing Combination of Thoracic and Abdominal CTA Image Quality and Radiation Dose Discussion

目的:探讨MSCT螺距对胸腹部CTA图像质量的影响,并比较辐射剂量。资料与方法:搜集临床拟诊为胸腹部血管病变的患者90例,按不同螺距随机分3组(n=30例):A组,螺距1.375:1、床速55mm/s;B组,螺距0.984:1、床速39.37mm/s;C组,螺距0.516:1、床速20.62mm/s;均采用相同的注射速率及对比剂量进行对比剂追踪触发扫描。获取数据后由影像主任医师和主管技师各一位在AW4.4工作站进行图像质量评价。结果:通过螺距优化后,A、B、C3组平均每位患者扫描时间分别为:(12.60±0.54)s、(17.40±0.44)s、(33.10±1.48)s。DLP分别为:(1462.50±71.56)mGy·cm、(2010.55±62.14)mGy·cm、(3821.58±198.50)mGy·cm。它们之间的差异具有明显的统计学意义(P<0.01)。3组的有效剂量(ED)分别为:24.96mSv、34.18mSv、64.97mSv。A组比B组的每位患者ED减少9.22mSv,降低了26.97%(9.22/34.18)。A组比C组的每位患者ED减少40.01mSv,明显降低了61.58%(40.01/64.97)。3组在胸主动脉、肾门水平腹主动脉、双侧髂外动脉末段平均CT值分别为:353.00Hu、350.77Hu、350.70Hu,3组间差异不具有统计学意义(P>0.05),重组血管清晰度及显示血管分支数亦无明显差异。结论:采用A组螺距优化、快的床速扫描参数可以明显地减少患者的辐射剂量,达到既保证图像质量又符合诊断要求。

Objective：To evaluate the pitch of the thoracic and abdominal MSCT CTA image quality,and compare the radiation dose.Materials and Methods：Collection of clinical suspected thoracic and abdominal vascular lesions in 90 patients,according to the different pitch were randomly divided into 3 groups（n=30）,group A：a pitch of 1.375：1,55 mm/s bed velocity;group B：a pitch of 0.984：1,39.37 mm/s bed velocity;group C：pitch,0. 516：1 bed velocity 20.62 mm/s,using the same injection rate and dose of contrast contrast tracking trigger scanning.After obtaining data from imaging director and supervisor technician in a AW4.4 workstation for image quality evaluation.Results：Through the pitch after optimization,A,B,C 3 groups average each patient scan time respectively：（12.60±0.54）s,（17.40±0.44）s,（33.10±1.48）s,DLP respectively：（1 462.50±71.56）mGy.cm, （2 010.55±62.14）mGy.cm,（3 821.58±198.50 the difference between mGy.cm）,which was statistically significant（P0.05）, recombinant vascular definition and display of vascular branching number also no difference.Conclusion：The groups A pitch optimization,fast bed velocity scanning parameters can significantly reduce the patient radiation dose,so as to ensure the image quality and meet the requirements of diagnosis.