全数字乳腺X线3种摄影模式的影像质量和辐射剂量比较

Comparison of different exposure modes with full-field digital mammography： image quality versus radiation dose

目的探讨全数字乳腺X线摄影（FFDM）不同摄影模式影像质量与辐射剂量的比较研究。方法用全数字乳腺X线摄影的对比度优先模式（CNT）、标准模式（STD）及辐射剂量优先模式（DOSE）对FLUKENA18—220乳腺模体进行摄影，摄影采用自动曝光模式（AEC），记录摄影条件和辐射剂量。由4位影像学医师在相同条件下进行软阅读，并按照美国放射学会（ACR）的评分标准对模体中的钙化点、尼龙纤维、肿块灶进行评分。结果标准模式、辐射剂量优先模式及对比度优先模式的模体影像评分值分别是j1．5、11．0和14．5，标准模式及辐射剂量优先模式与对比度优先模式的影像质量差异有统计学意义（F=41．321，P〈0．05）。标准模式与辐射剂量优先模式之间影像质量差异无统计学意义，但两种模式的辐射剂量却不相同，其表面入射剂量分别是4．5和3．15mGy，腺体平均剂量（AGD）分别是1．18和0．78mGy。结论全数字乳腺摄影的辐射剂量优先模式和标准模式适合大多数被检者，特别是辐射剂量优先模式。对比度优先模式应严格控制使用。

Objective To study the difference of image quality and radiation dose between different exposure modes with full-field digital mammography （FFDM）. Methods The Fluke18-220 mammographic phantom was exposed by FFDM system with different exposure modes at automatic exposure control （AEC）, including contrast mode, standard mode and dose mode, and the exposure factors and radiation dose were recorded. The images on monitor with the best window width and window level were read by four independent radiologists. The images of specks groups, nylon fibers and masses was assessed by the four experienced readers at the criterion of American College of Radiology. Results The detection of specks groups, nylon fibers and masses were statistically different at the contrast mode and standard mode （ F =41. 321, P 〈 0.05 ） , further at the contrast mode and dose mode. The detection of specks groups, nylon fibers and masses were not statistically different（ P 〉 0. 05 ） at standard mode and＂ dose mode, but the radiation doses were different. The ESD at standard mode and dose mode was 4.5 and 3.15 mGy, respectively. The AGD of standard mode and dose mode was 1.18 mGy and 0.78 mGy, respectively. Conclusions The standard mode and dose mode of FFDM might be fit for most patients, especially at the dose mode. Contrast mode of FFDM should be strictly controled in use.