中华放射医学与防护杂志

赵永霞,常津,左紫薇,张畅达,张天乐.胸主动脉CT血管造影自适应性统计迭代重建权重和低剂量扫描条件的优化[J].中华放射医学与防护杂志,2014,34(11):867-869

胸主动脉CT血管造影自适应性统计迭代重建权重和低剂量扫描条件的优化

Optimization of low-dose protocol in thoracic aorta CTA: weighting of adaptive statistical iterative reconstruction (ASIR) algorithm and scanning parameters

投稿时间：2013-11-13

DOI：10.3760/cma.j.issn.0254-5098.2014.11.019

中文关键词: 适应性统计迭代重建辐射剂量影像质量胸主动脉CT血管造影

英文关键词:Adaptive statistical iterative reconstruction Radiation dose Image quality Thoracic aorta CTA

基金项目:

作者	单位	E-mail
赵永霞	天津大学精密仪器与光电子工程学院, 天津 180072
常津	天津大学精密仪器与光电子工程学院, 天津 180072	jinchang@tju.edu.cn
左紫薇	河北大学附属医院
张畅达	河北大学附属医院
张天乐	河北大学附属医院

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中文摘要:

目的探讨胸主动脉CT血管造影(CTA)成像时的适应性统计迭代重建(ASIR)的最佳权重和优化低剂量扫描参数.方法将体质量指数为19~24 kg/m²的120例患者随机数字表法分成6组,用宝石能谱CT进行胸主动脉CTA扫描,扫描范围为290~330 mm,第1组扫描条件为机器默认的100 kV、240 mAs,使用10%~100%权重的适应性统计迭代重建,对图像进行重建并计算信噪比(SNR)及对比度噪声比(CNR),请两位影像学家对图像进行5分值主观评价,优选出最佳图像质量的ASIR权重,在此权重基础上固定100 kV,用210、180、 150、120 及90 mAs对其他5组患者进行扫描,记录不同mAs的CTDI_vol及DLP,并转换为有效剂量E.计算上述图像的SNR及CNR,并进行主观评价.结果 100 kV、240 mAs 扫描条件下图像的最佳ASIR权重为60%.ASIR权重为60%、100 kV下240~90 mAs扫描产生图像进行主观评价分值分别为(4.78±0.30)~(3.15±0.23);其CTDI_vol、DLP平均值分别为: 12.64~4.41 mGy和331.81~128.27 mGy,并将DLP转换为E为4.98~1.92 mSv.120~240 mAs各组的影像质量差异无统计学意义(F＝5.365,P>0.05),但120 mAs的CTDI_vol、DLP及E较240 mAs分别低53.4%、48.5%及49.9%. 结论在进行胸主动脉低剂量CTA成像时最佳的ASIR权重为60%.体质量指数为19~24 kg/m²的被检者胸主动脉低剂量CTA扫描的最佳mAs 为120 mAs (100 kV时).

英文摘要:

Objective To investigate the best weighting of adaptive statistical iterative reconstruction (ASIR) algorithm and optimized low-dose scanning parameters in thoracic aorta CT angiography(CTA). Methods Totally 120 patients with the body mass index (BMI) of 19-24 were randomly divided into 6 groups. All patients underwent thoracic aorta CTA with a GE Discovery CT 750 HD scanner (ranging from 290-330 mm). The default parameters (100 kV,240 mAs) were applied in Group 1. Reconstructions were performed with different weightings of ASIR(10%-100% with 10%), and the signal to noise ratio (S/N) and contrast to noise ratio(C/N) of images were calculated. The images of series were evaluated by 2 independent radiologists with 5-point-scale and lastly the best weighting were revealed. Then the mAs in Group 2-6 were defined as 210,180,150,120 and 90 with the kilovoltage 100. The CTDI_vol and DLP in every scan series were recorded and the effective dose (E) was calculated. The S/N and C/N were calculated and the image quality was assessed by two radiologists. Results The best weighing of ASIR was 60% at the 100 kV,240 mAs. Under 60% of ASIR and 100 kV, the scores of image quality from 240 mAs to 90 mAs were(4.78±0.30)-(3.15±0.23). The CTDI_vol and DLP were 12.64-4.41 mGy and 331.81-128.27 mGy, and the E was 4.98-1.92 mSv. The image qualities among Group 1-5 were nor significantly different (F＝5.365,P>0.05), but the CTDI_vol and DLP of Group 5 were reduced by 37.0% and 36.9%,respectively compared with Group 1. Conclusions In thoracic aorta CT Angiography, the best weighting of ASIR is 60%, and 120 mAs is the best mAs with 100 kV in patients with BMI 19-24.

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