两种数字乳腺X射线摄影系统的比较

Full-field digital mammography versus computed radiology mammography： comparison in image quality and radiation dose

目的 探讨比较全视野数字乳腺X射线摄影系统（FFDM）与计算机乳腺X射线摄影系统（CRM）在影像质量与辐射剂量方面的差异。方法 用FFDM对ALVIM乳腺摄影体模TRM进行自动曝光控制（AEC）摄影，再用CRM专用成像板（IP）在同一摄影机上用相同条件对体模摄影。固定AEC摄影时的kV值，选用曝光量数值14、16、18、22和24mAs，在FFDM机上对模体摄影，记录上述摄影条件和入射皮肤剂量（ESD）及平均腺体剂量（AGD）。由5位影像科资深医师分别在相同条件下对所得影像进行软阅读，按照5分值判断法评判，然后绘制受试者工作特征曲线（ROC）曲线，计算出每种信号的判断概率值（Pdet），对所得数据进行统计学分析。结果 在辐射剂量均为1．36mGy时，FFDM对模体内钙化点和肿块灶Pdet值比CRM高，尤其是微小钙化点和小肿块灶，微小钙化点最大差值为0．215，小肿块灶最大差值为0．245。在相同的Pdet值下，FFDM的辐射剂量比CRM低，ESD的值降低了26％，腺体平均剂量降低了41％。在使用FFDM摄影时，当mAs值超过AEC值时，Pdet值没有明显改变。结论在相同曝光条件下，FFDM对乳腺钙化点和肿块灶的检出率高于CRM；在获得相似图像质量时，FFDM的辐射剂量明显低于CRM。

Objective To investigate the differences in image quality and radiation dose between fullfield digital mammography （FFDM） system and compute radiology mammography （CRM） system. Methods The ALVIM mammographic phantom was exposed by FFDM system with automatic exposure control （AEC） and then exposed by CRM system with the unique imaging plank on the same condition. The FFDM system applied the same kV value and the different mAs values （14, 16, 18, 22 and 24 mAs）, and the emission skin dose （ESD） and the average gland dose （AGD） were recorded for the above-mentioned exposure factors. All images were read by five experienced radiologists under the same condition and judged based on 5-point scales. And then receive operating characteristic （ROC） curve was drawn and the probability （Pdo,） values were calculated. The data were statistically processed with ANOVA. Results The Pdet, values of calcifications and lesion lump were higher with FFDM system than with CRM system at the same dose （1.36 mGy）. Especially, for microcalcifications and lesion lump, the largest difference of the Pdet, value was 0.215, and that of lesion lump was 0.245. In comparison with CRM system, the radiation dose of FFDM system could be reduced at the same Pdet, value. The ESD value was reduced by 26%, and the AGD value was reduced by 41% . When the mAs value exceed AEC value, the pdet, value almost had no change, though the radiation dose was increased. Conclusions The detection rates of microcalcifications and lesion lump with FFDM system are proven to be superior to CRM system at the same dose. The radiation dose of FFDM system was less than CRM system for the same image quality.