数字乳腺摄影机3种阳极靶滤过组合影像质量与辐射剂量的对比研究

Comparison of different anode filter combination with full-field digital mammography： imaging quality versus radiation dose

目的探讨数字乳腺摄影机钼／钼（Mo／Mo）、钼／铑（Mo／Rh）、铑／铑（Rh／Rh）阳极靶滤过组合影像质量与辐射剂量的差异。方法用全数字乳腺X线摄影机的Mo／Mo、Mo／Rh、Rh／Rh阳极靶滤过组合对FLUKE NA18—220乳腺模体进行摄影，摄影采用自动曝光模式，4名医师分别扫描3次，分别记录摄影条件和辐射剂量，计算平均值。所得图像在相同条件下进行阅读，并按照美国放射学院（ACR）的评分标准对模体中的钙化点、纤维组织、肿块灶进行评分，并计算平均值，并采用方差分析对评分进行比较。结果Mo／Mo、Mo／Rh和Rh/Rh阳极靶滤过组合在自动曝光模式下，对模体影像中纤维组织的评分分别为（5．50±2．12）、（5．38±1．98）和（5．38±1．98）分，差异无统计学意义（F=4．56，P〉0．05）；对钙化点的评分分别为（4．50±1．85）、（4．25±1．56）和（4．38±1．68）分，差异也无统计学意义（F=4．32，P〉0．05）；对肿块灶的评分分别为（4．38±1．38）、（4．38±1．38）和（4．25±1．56）分，差异有统计学意义（F=36．65，P〈0．05）。Rh／Rh的表面入射剂量和平均腺体剂量分别为（5．11±1．89）和（1．08±0．13）mCy，Mo／Mo分别为（6．66±2．33）和（1．29±0．38）mGy，Mo／Rh分别为（5．67±2．02）和（1．29±．38）mGy，Rh／Rh较Mo／Mo及Mo／Rh的表面入射剂量和平均腺体剂量均低。Mo／Rh阳极靶滤过组合较Mo／Mo表面入射剂量低。结论Rh／Rh和Mo／Rh靶滤过组合由于辐射剂量低且能清晰显示乳腺内的病变，因此适合大多数乳腺腺体进行摄影，Rh／Rh靶滤过组合的电压较高，穿透力较强，因此在腺体厚度较厚时首选Rh／Rh靶滤过组合。Mo／Mo靶滤过组合对肿块灶的显示较高，因此在需要高分辨率影像时选用Mo／Mo靶滤过组合。

Objective To compare imaging quality and radiation dose of different anode filter combination for full-field digital mammography. Methods The image of FLUKE NA 18-220 phantom were taken at full-field digital mammography （FFDM）, system with Mo/Mo, Mo/Rh, Rh/Rh anode/filter combination by automatic exposure control, record the exposure factors and doses. The images on monitor with the best window width and window level were read by 4 independent radiologists, the images of specks groups, nylon fibers and masses was assessed by the 4 experienced readers at the criterion of American College of Radiology 1999 mammography quality control manual. Statistical analysis was performed using analysis of variance. Results The nylon fibers scores of Mo/Mo, Mo/Rh and RE/Rh were 5.50 ± 2. 12, 4. 50 ± 1.85 and 4. 38 ± 1.38 ; the specks groups scores of Mo/Mo, Mo/Rh and Rh/Rh were 5.38 ± 1.98, 4. 25 ± 1.56 and 4. 38 ± 1.38 ;the masses scores of Mo/Mo,Mo/Rh and Rh/Rh were 5.38 ± 1.98, 4. 38 ± 1.68 and 4. 25 ± 1.56, the detection of specks groups, nylon fibers was not statistically significant （ F = 4. 56 and 4. 32 ,P 〉 0. 05 ）, but the detection of masses was statistically significant （ F = 36. 65 ,P 〈 0. 05 ）. The radiation doses were different, the entrance surface dose （ESD） and average glandular dose （AGD） of Rh/Rh were （5. 11 ± 1.89） and （1.08 ±0. 13） mGy, the ESD and AGD of Mo/Mo were （6. 66 ±2. 33） and （ 1.29 ± 0. 38 ） mGy, the ESD and AGD of Mo/Rb anode/filter combination were （ 5.67 ± 2.02 ） and （ 1.29 ± 0. 38 ） mGy. Conclusions The radiation dose of Rh/Rh and Mo/Rh anode/filter combination of FFDM were lower, and the imaging was clear, so Rh/Rh and Mo/Rh anode/filter combination of FFDM prefer to mostly patients, especially when the thinkness is large, Rh/Rh anode/filter combination is preferred, because the kV values was higher, the penetration of X-ray was stronger. The Mo/Mo anode/filter combination was used when the needs of high-resolution, because the detection of masses of it was better.