自适应统计迭代重建技术在降低学龄前儿童胸部CT检查辐射剂量的应用研究

发布时间：2018-09-01 05:23

【摘要】：目的:探讨自适应统计迭代重建技术(ASiR)在学龄前儿童胸部CT扫描中的应用价值。方法:临床预试验:选取0-1岁胸部CT检查患儿80名,随机分为4组,每组20名;1-3岁胸部CT检查患儿140名,随机分为7组,每组20名;3-6岁胸部CT检查患儿180名,随机分为9组,每组20名;预设噪声指数范围为9-17,均采用Z轴自动管电流调节技术、管电压100KV,管电流20-150 m A,FBP重建,比较分析不同噪声指数条件下影像SNR、影像噪声、CTDIvol、DLP、ED等,并对影像质量进行评价,寻找满足诊断要求各年龄段患儿噪声指数的最大临界值。临床试验:选取0-1岁、1-3岁、3-6岁行胸部CT平扫+增强检查患儿各30名;平扫序列,0-1岁患儿预设噪声指数为12,1-3岁患儿预设噪声指数为15,3-6岁患儿预设噪声指数为17,采用Z轴自动管电流调节技术、管电压100KV,管电流20-150m A;增强扫描序列,0-6岁患儿预设噪声指数均为9,其余扫描参数与平扫序列相同;患儿增强扫描序列数据采用FBP重建算法;患儿胸部平扫序列数据采用自适应统计迭代重建技术(ASiR)进行图像重建,以10%为步涨值,重建为0%-100%等11组图像,0%即为传统的FBP重建算法,比较分析不同权重ASi R重建技术条件下影像SNR、影像噪声等,并分析比较各组影像的主观质量,探求出0-6岁患儿在各个年龄阶段行胸部CT扫描时不同权重ASiR重建技术与胸部CT影像质量的关系,并探求其ASiR重建技术的最佳权重范围。结果:临床预试验:0-1岁、1-3岁、3-6岁的患儿采用噪声指数分别为11、14、16时所扫描重建的图像既满足诊断需求,又显著降低患儿单次辐射剂量,为各年龄阶段噪声指数的最大临界值。临床试验:影像噪声随着ASi R重建技术权重的增加而降低,影像SNR随着ASi R重建技术权重的增加而增加,影像主观质量评价得分先随着ASi R重建技术权重的增加而增加,当达到最佳权重范围后会随着ASiR重建技术权重的增加而降低;0-1岁患儿影像ASiR最佳权重肺窗为50%、纵隔窗为40%;1-3岁患儿影像ASiR最佳权重肺窗为60%、纵隔窗为50%;3-6岁患儿影像ASiR最佳权重肺窗为70%、纵隔窗为60%。结论:在学龄前儿童胸部低剂量CT扫描中,应用ASiR迭代重建技术能显著提高影像图像质量,降低影像噪声,0-1岁患儿影像ASiR最佳权重肺窗为50%、纵隔窗为40%;1-3岁患儿影像ASiR最佳权重肺窗为60%、纵隔窗为50%;3-6岁患儿影像ASiR最佳权重肺窗为70%、纵隔窗为60%。
[Abstract]:Objective: to evaluate the value of adaptive statistical iterative reconstruction technique (ASiR) in chest CT scanning of preschool children. Methods: clinical preclinical trial: 80 children aged 0-1 years old with CT were randomly divided into 4 groups, each group consisted of 20 children aged 1-3 years with chest CT, and were randomly divided into 7 groups, each group consisted of 20 children aged 3 to 6 years old, 180 children with chest CT were randomly divided into 9 groups. The preset range of noise index is 9-17. All of them adopt Z-axis automatic tube current regulation technique, the voltage of the tube is 100kV, the current of the tube is 20-150m Agna FBP reconstruction, the noise of image SNR, image is compared and analyzed under different noise index conditions, and the image quality is evaluated. To find the maximum critical value of noise-index to meet the diagnostic requirements of children with different age groups. Clinical trial: 30 cases of children aged 0-1 years old and 1-3 years old and 3-6 years old were examined by plain enhanced chest CT. The preset noise index of children aged 0-1 years was 12 ~ 1-3 years old. The preset noise index of children aged 153-6 years was 17. The Z-axis automatic tube current regulation technique was used. The voltage of the tube is 100kV, the current of the tube is 20-150mA, the default noise index of the children aged 0-6 years is 9, the other scanning parameters are the same as those of the plain scan sequence, the data of the enhanced scan sequence are reconstructed by FBP algorithm. Using adaptive statistical iterative reconstruction technique (ASiR) to reconstruct children's chest plain scan sequence data, 11 groups of images, such as 0% -100%, were reconstructed with 10% step value and 0% 0% respectively, which was the traditional FBP reconstruction algorithm. Comparing and analyzing the image SNR, image noise under the condition of different weight ASi R reconstruction technology, and analyzing and comparing the subjective quality of each group of images, To explore the relationship between ASiR reconstruction techniques with different weights and the quality of chest CT images in children aged 0-6 years, and to find out the best weight range of ASiR reconstruction techniques. Results: in clinical pre-trial, the noise index of children aged 1-3 years and 3-6 years were 1114, respectively. The reconstructed images scanned at 16:00 not only satisfied the diagnostic needs, but also significantly reduced the single dose of radiation, which was the maximum critical value of noise index in each age stage. Clinical trial: the image noise decreased with the increase of the weight of ASi R reconstruction technology, the image SNR increased with the increase of the weight of ASi R reconstruction technology, and the evaluation score of image subjective quality first increased with the increase of the weight of ASi R reconstruction technology. When the optimal weight range is reached, it will be reduced with the increase of the weight of ASiR reconstruction technique. The best weight lung window of ASiR for children aged 0-1 years is 50, the mediastinal window is 400-1-3 years old, the best weight lung window of ASiR is 60th and the mediastinal window is 500-6 years old. The best weight for ASiR is 70 for lung window and 60 for mediastinal window. Conclusion: in low dose CT scanning of preschool children, the application of ASiR iterative reconstruction technique can significantly improve the image quality. The best weight lung window of ASiR for children aged 0-1 years was 50g, the best weighted lung window of ASiR for children aged 1-3 years was 600.The best weighted lung window of ASiR for children aged 3-6 years was 700.The best weight lung window for mediastinal window was 600.The best weight lung window for mediastinal window was 60mm for children aged 3-6 years.
【学位授予单位】：西南医科大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R816.92

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