数字乳腺X线摄影中采用影像噪声特征评价图像质量的研究  

Research of using image noise characteristic to evaluation image quality in digital mammography

作　　者：康天良[1] 牛延涛[1,2] 刘云福[1,2] 张宗锐[1,2] 张永县[1,2] 李静[1,2] 李海云[1] 

机构地区：[1]首都医科大学生物医学工程学院,100069 [2]首都医科大学附属北京同仁医院放射科

出　　处：《中华放射学杂志》2012年第10期932-936,共5页Chinese Journal of Radiology

基　　金：基金项目：北京市科技新星计划资助项目（2009B43）

摘　　要：目的通过对数字乳腺X线摄影系统噪声特征的分析，评价影像噪声特性的适宜表达方式。方法采用固定管电流量90mAs，在钼（Mo）和铑（Rh）滤过下，在23—35kVp范围内共13个不同的管电压对对比度细节模体CDMAM曝光；采用固定管电压29kVp，Mo和Rh滤过下，在20-00mAs范围内10个不同的管电流量对CDMAM模体曝光。对所得CDMAM模体影像分别测量和计算信号区和信号区旁背景区域的标准差、联合标准差、相减标准差和相对标准差，并用软件计算CDMAM模体的影像质量评分。采用秩和检验比较上述不同条件下计算的背景标准差、联合标准差、相减标准差值的差异，对不同曝光模式下的Mo、Rh滤过2组图像的CDMAM影像质量评分比较采用t检验。结果在使用Mo靶、90mAs时，分别采用Mo和Rh滤过，随管电压增加，标准差逐渐增大，相对标准差逐渐减小；采用Mo滤过，背景标准差、联合标准差和相减标准差的中位数分别为10．91、10．34和9．87，采用Rh滤过，上述标准差分别为11．24、10．57和9．96，差异有统计学意义（χ^2=26．0，P〈0．01）。在使用Mo靶、29kVp时，分别选择Mo和Rh滤过，随管电流增加，标准差逐渐增大，相对标准差逐渐减小；采用Mo滤过，背景标准差、联合标准差和相减标准差的中位数分别为12．30、11．61和11．05，采用Rh滤过，上述标准差分别为12．29、11．58和10．87，差异有统计学意义（χ^2=20．0，P〈0．01）。管电流均采用90mAs，采用不同管电压，Mo滤过条件下，影像评分为（149．14±23．87）分，Rh滤过条件下影像评分为（139．16±23．14）分，差异有统计学意义（t=9．129，P〈0．01）。管电压均采用29kVp，采用不同管电流，Mo滤过条件下，影像评分为（149．75±34．85）分，Rh滤过条件下影像评分为（145．2±34．64）分，差异无统计学意义（t=1．304，P〉0．05）。相对标�Objective To find the proper way of assessing the image noise characteristic through the analysis of noise characteristic in the digital mammographic images. Methods The CDMAM phantom was firstly exposed with different filter materials and tube voltages in the range of 23 to 35 kVp at a fixed tube current 90 mAs, then exposed with different filter materials and tube current in the range of 20 to 200 mAs at a fixed tube voltage 29 kVp. The parameters such as background standard deviation ,joint standard deviation, subtracted standard deviation and relative standard deviation were calculated and measured from both 60 pixels of signal disc and background beside of the disk for all the images. The IQFinvs were calculated for the achieved images. Non-parametric rank sum tests were used to compare the difference of the background standard deviation,joint standard deviation and subtracted standard deviation, t test was used to compare the IQFinvs between Mo and Rh tilers in each group. Results With the same exposure parameters in the test above, the maximum value was the background standard deviation, while the subtracted standard deviation was the minimum, and the value of joint standard deviation was in the middle. With other parameters unchanged, the values of three kind of standard deviation increased with the increasing of tube voltage or tube current, while the differences between them getting more significant. Under the condition of 90 mAs and Mo filter material, background standard deviation, joint standard deviation, subtracted standard deviation were 10. 91,10. 34 and 9. 87,the results were 11.24, 10. 57 and 9. 96 while Rh filter material was used, significant difference was found （ χ^2 = 26. 0, P 〈 0. 01 ）. Under the condition of 29 kVp and Mo filter material, background standard deviation, joint standard deviation, subtracted standard deviation were 12. 30, 11.61 and 11.05,the results were 12. 29, 11.58 and 10. 87 while Rh filter material was used, significant difference was found（ χ^2 = 20.0, P �

关 键 词：乳房X线摄影术 噪声 对比分析 

分 类 号：R816.4[医药卫生—放射医学]