摘要
背景:在CT图像中,图像噪声水平与影像质量密切相关,它直接影响和限制着CT对低对比度物质的分辨力。目的:通过图像空间添加噪声软件模拟低剂量CT图像,分析模拟噪声指数与不同组织噪声的相关性及胸部不同组织的噪声变化特点。方法:利用图像空间添加噪声软件对20名自愿者在常规参数下扫描获得的原始图像进行噪声添加,模拟10,30,50,80,100,120,150,180及240mA共9组胸部低剂量图像,记录每幅图像噪声指数,测量主动脉弓层面、心脏层面、肺底3个层面的胸壁软组织、主动脉、脊柱、肺组织及空气中CT值的标准差。结果与结论:图像添加法计算的模拟噪声指数与主动脉弓及其他组织噪声实测噪声差异有显著性意义(P<0.05),呈线性相关。胸部低剂量扫描时,当管电流在10～50mA时噪声显著增加,80～240mA时模拟噪声值随着管电流增高降低幅度逐渐减低。胸部各组织120mA组与180mA组图像噪声差异无显著性意义(P>0.05)。提示图像空间添加噪声软件的噪声指数反映了图像不同组织的整体噪声水平。胸部低剂量CT检查时采用管电流120～180mA时能够保证各组织噪声无明显变化的同时又可以降低辐射剂量。
BACKGROUND：Image noise level is closely related with the image quality in the CT images,it directly affects and limits of CT resolution of low-contrast material.OBJECTIVE：To evaluate the correlation of estimated noise with the noise of different tissues and to analyze characteristic of different tissues noise on low dose chest scan by adding noise on raw data to simulate low dose scan.METHODS：The noise was artificially introduced to the images of 20 volunteers using an image space noise addition tool to simulate nine groups of low dose scans with tube current of 10,30,50,80,100,120,150,180 and 240 mA.The estimated noise of images was recorded.The noise of aorta,tissue of chest wall,vertebra,lung and air on levels of aortic arch,heart and liver were measured.RESULTS AND CONCLUSION：There was significant statistical difference between the estimated noise and the measured noise in the index of aortic artery and other tissues estimated noise （P〈0.05）,which had linear correlation.The noise of different tissues increased significant in groups of 10-50 mA,and decreased gradually with the increase of current in groups of 80-240 mA.There was no statistical difference of the estimated noise value between the noise of 120 and 180 mA groups （P〈0.05）.The estimated noise of noise addition tool can be used to evaluate the image noise of different tissues.The tube current of 120 mA to 180 mA in low dose chest CT scan can reduce radiation dose and keep the image quality of different tissues.
出处
《中国组织工程研究》
CAS
CSCD
2012年第9期1577-1580,共4页
Chinese Journal of Tissue Engineering Research
基金
重庆市卫生局科研基金资助项目(08-2-29)~~
