全数字乳腺摄影系统与双面阅读CR乳腺摄影系统的比较

Comparison of full-field digital mammography system and dual-sided CR mammography system for imaging quality and radiation dose

目的对比研究全数字乳腺摄影系统（FFDM）与双面阅读CR乳腺摄影成像系统（DSCRM）辐射剂量与成像质量的关系。方法在相同的辐射剂量下用FFDM和DSCRM对ALVIM统计学乳腺摄影模体TRM进行曝光，记录摄影条件和模体表面入射剂量，然后固定此摄影条件kV值，选用不同mAs值用DSCRM对模体进行曝光，记录表面入射剂量，并将所获取的影像在图像诊断工作站显示器上由3位放射学专家进行视读打分，按照5分值判断法评判，绘制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。结果在辐射剂量为1．36mGy时，FFDM所摄取模体影像内容物中不同直径钙化点和肿块灶的P。值分别是0．730—0．925和0．670～0．945，DSCRM所得模体影像内容物中不同直径钙化点和肿块灶的Pd．t值分别是0．632～0．815和0．575～0．785。二者在1．35mm肿块灶和0．40mm钙化点用双因素方差分析（ANOVA）进行处理，（F=37．1，P〈0．05）。在相同的判断概率值Pdet下，DSCRM所用表面入射剂量为1．63mGy，腺体平均剂量为0．65mGy，FFDM所用的表面人射剂量为1．36mGy，腺体平均剂量为0．56mGy，FFDM较DSCRM表面入射剂量减少了19．8％，腺体平均剂量减少16．0％。结论在相同曝光条件下，FFDM对模体内容物的检出率高于DSCRM；在获得相似图像质量时，FFDM的辐射剂量明显低于DSCRM。

Objective To compare imaging quality and radiation dose on full-field digital mammography （FFDM） system and dual-sided reading CR mammography （DSCRM） system. Methods The TRM of ALVIM statistics phantom was exposed by FFDM system and （DSCRM） with the same radiation dose. The exposure parameters and the entrance surface dose （ESD） were recorded. Then, the phantom was exposed by DSCRM system with different mAs and same kV, and the ESD was recorded. The images obtained above were read by three radiologists on the monitor of diagnosis work station with the same window width and window level. The evaluation of the images were given using a five-level confidence scale. ROC curves were drawn and probability Pdo, were calculated. Results The ROC analysis of microcaleifications and masses showed A（z） values of 0. 730 -0. 925 and 0. 670 -0. 945 for FFDM, and 0. 632-0. 815 and 0. 575 -0. 785 for DSCRM when the radiation dose is 1.36 mGy. The radiation dose with DR system could be reduced compared with dual-sided reading CR system at the same probabilities Pde,, the ESD reduced from 1.63 mGy to 1.36 mGy by 19.8% , the AGD reduced from 0.65 mGy to 0.56 mGy by 16.0%. Conclusions The observable details with FFDM system were proved to be superior to DSCRM system at the same radiation dose. With the similar image quality, the radiation dose of FFDM system was less than the DSCRM system.