数字乳腺X线摄影曝光模式对乳腺体模图像质量和辐射剂量的影响

Effect of digital mammography exposure modes on image quality and radiation dose of breast phantom

目的:比较数字乳腺X线摄影曝光模式对乳腺体模图像质量和辐射剂量的影响,为乳腺癌的影像诊断提供依据。方法:将乳腺体模一次成像。自动曝光模式,分别应用低剂量(Dose)、标准(STD)和高对比度(CNT)3种曝光模式;手动曝光模式,固定管电流量32 mAs,分别改变管电压为25、26、27、28、29、30、32、34、36、38和40kV曝光11次;固定管电压29kV,分别改变管电流量为20、32、40、45、56、63、80、100、125、160和200mAs曝光11次。记录各曝光参数下平均腺体剂量(AGD)值,并根据美国放射学会(ACR)评分标准对图像质量进行评价。结果:3种自动曝光模式下,模拟纤维组织的图像质量评分比较差异有统计学意义(P=0.00),模拟钙化和模拟团块的图像质量评分比较差异无统计学意义(P=0.37)。手动曝光模式下,固定管电流量32mAs,改变管电压或固定管电压29kV,改变管电流量曝光,3种模拟病变图像质量评分比较差异均有统计学意义(P=0.00),但3种模拟病变的图像质量评分受管电压或管电流量增加而且引起的变化趋势不同。管电流量或管电压变化对模拟纤维组织的图像评分影响最大,对模拟钙化的图像评分影响最小。自动曝光模式以低剂量模式AGD值最低,高对比度模式AGD最高;手动曝光模式时,AGD随管电压和管电流量增加而增加,均呈正相关关系(R2=0.998,P=0.000;R2=0.979,P=0.000)。结论:数字乳腺X线摄影时,可采用自动曝光的低剂量模式行乳腺癌筛查。使用手动曝光模式行常规临床检查能有效降低辐射剂量。

Objective To compare the effect of different digital mammography exposure modes on the image quality and radiation dose of the breast phantom,and to provide the basis for diagnosis of breast cancer.Methods A breast phantom was exposed by using automatic exposure mode and manual exposure mode,respectively.There were three automatic exposure modes including DOSE,STD,and CNT.About manual exposure mode,at first,the tube voltage was changed,such as 25,26,27,28,29,30,32,34,36,38,and 40 kV,when the tube loading was 32 mAs.Then the tube loading was changes,such as 20,32,40,45,56,63,80,100,125,160,and 200 mAs,when the tube voltage was 29 kV.According to American College of Radiology（ACR）criteria,the average glandular dose（AGD） and image quality score were recorded for each image.Results Among the three automatic exposure modes,there were no statistical difference of the quality score of images of the simulated specks and the simulated masses（P=0.37）,while there was statistical difference of the quality score of images of the simulated fibers（P=0.00）.When exposuring with the manual mode,there were statistical differences of the quality scores of images of three simulated lesions（P=0.00）.However,there were different trend changes in the quality scores of images of three simulated lesions.The imaging of simulated fibers was most susceptible by changing of tube voltage or tube loading,while the imaging of simulated specks was least susceptible by changing of tube voltage or tube loading.AGD value will be increasd with the increasing of tube voltage or tube loading,whenever the automatic exposure mode or manual exposure mode.Conclusion When digital mammography being,it must be executed to the breast cancer screened with the low dose model of automatic exposure.And the manual mode can effectively reduce the radiation dose without sacrifice image quality.