摘要
目的探索64层螺旋以CT低剂量扫描在儿童鼻窦中的应用,获得不同参数的辐射剂量并对图像质量进行评估。方法采用Toshiba 64排螺旋DT,分别选择管电压为120和100 kV时,转速0.5 s/rot,螺距41,用80、40、30、20、10mA的剂量对1具儿童尸体头颅标本鼻窦进行扫描,比较不同参数时的图像质量。选取能满足临床需求的最低辐射剂量作为扫描参数。并用该参数对33例儿童鼻窦炎患者进行扫描。评价图像的质量和显示精细结构的能力。结果当毫安值从100mA降到30mA时,辐射剂量明显下降,保持30mA不变,100 kV时有效CT剂量指数(DTDIvol)明显小于120 kV(3.1mGy比4.8mGy)。当mA降至20mA以下,图像质量明显变差。用100 kV、30mA进行33例儿童鼻窦扫描,鼻窦内各结构显示清晰,所有图像均满足临床需求。DTDI_(VOL)平均为3.03±0.09(mGy),剂量长度乘积(DLP)为30.63±2.58(mGy·cm),有效辐射剂量为0.07±0.003(mSv),仅为常规剂量的1/10。结论采用64层螺旋CT以100kV、30mA(15mAs)作为扫描条件检查儿童鼻窦,可能是满足临床要求的最低剂量。
Objective To optimize radiation dose of multi-detector row CT （MDCT） of the paranasal sinuses in children. Methods 64-detector row spiral CT scans （Toshiba Aquilion） of a pediatric cadaver head were performed with 0.5 s/rot, pitch 41 at tube potential of 120 kV and 100 kV respectively using varying tube current of 80, 40, 30, 20, and 10 mA. The CT dose indexes and images were compared among the different tube current groups. The minimum kV and mA values were determined. Thirty-three children were then examined to test the clinical validity of the minimum 100 kV and 30 mA values. Results The CT radiation dose was significantly lower when the tube current was reduced from 80 to 10 mA. At the same 30 mA, the CT radiation dose of 100 kV （3.1mGy） was less than that of 120 kV （4.8 mGy）. Below 20 mA, the image quality was poor. At 100 kV and 30 mA, the image quality of the paranasal sinuses in 33 children was satisfactory for diagnosis. The average CTDIVOL was 3.03±0.09 mGy and average DLP was 30.63±2.58 mGy. cm. The effective radiation dose was 0.07±0.003 mSv, which was only 1/10 of the routine radiation dosage. Conclusion Reduced CT radiation dose with diagnostic image quality of paranasal sinuses in children can be achieved at tube voltage of 100 kV and current of 30mA on a Toshiba Aquilion 64detector row spiral CT scanner.
出处
《影像诊断与介入放射学》
2012年第1期3-6,共4页
Diagnostic Imaging & Interventional Radiology
基金
教育部博士点基金新教师项目(编号200805581135)
