基于两种靶-滤过的数字乳腺机对致密型厚乳腺摄影结果的对比研究

目的 探讨对模拟致密型厚乳腺（压迫厚度>65 mm）的模体行全景数字乳腺X射线摄影（FFDM）检查，钼-铑（Mo-Rh）和钨-铑（W-Rh）两种靶-滤过组合对其辐射剂量及图像质量的影响。方法 用聚甲基丙烯酸甲酯有机玻璃（PMMA）模拟标准乳腺，再将铝片置于PMMA板中模拟致密型乳腺，对两组不同致密型（分别放置0.1和0.2 mm铝片）厚度为68 mm的模体进行自动、半自动曝光以及手动曝光，记录靶-滤过（T-F）组合方式、管电压、管电流、平均腺体剂量（AGD）、表面入射剂量（ESE）和图像质量因子反数值（IQFInv）。采用Pearson相关及回归分析评价AGD对IQFInv的影响，两组模体的靶-滤过组合对IQFInv和AGD的差异采用配对样本t检验。结果 AGD和IQFInv具有正相关（r=0.806~0.953，P<0.05）。对于0.1 mm铝片的模体，固定100 mAs或固定28 kVp，两组靶-滤过组合的AGD差异和IQFInv差异均具有统计学意义（t=3.162~8.028，P<0.05）。对于0.2 mm铝片的模体，固定100 mAs时，AGD差异和IQFInv差异均具有统计学意义（t=8.028、4.768，P<0.05）；固定28 kVp时，AGD差异具有统计学意义（t=7.730，P<0.05），IQFInv差异没有统计学意义（P>0.05）。此外，固定100 mAs时，采用W-Rh，两组模体的IQFInv差异具有统计学意义（t=2.345，P<0.05）。结论 对致密型厚乳腺模体采用W-Rh组合较Mo-Rh组合能在保证影像质量的前提下降低辐射剂量。相同管电流时，W-Rh组合在高管电压下对致密程度较高的乳腺模体的影像显示更佳。

Comparative study of the findings in thick dense breasts based on two target-filters in digital mammography: a phantom study

Objective To investigate the radiation dose to phantoms of thick dense breasts (compression thickness > 65 mm) and the influence of Molybdenum-Rhodium (Mo-Rh) and Wolfram-Rhodium (W-Rh)) target-filter combination on image quality in full field digital mammography (FFDM). Methods An aluminium plate was placed on polymethyl methacrylate (PMMA) plates to simulate dense breasts. Two of 68 mm in-depth phantoms were used to simulate photography condition of thick dense breasts with 0.1 and 0.2 mm aluminium plates respectively. The two phantoms were exposed automatically, half-automatically and manually. The parameters were recorded for each exposure including the target-filter(T-F), tube voltage (kV), tube current (mAs), average glandular dose (AGD), entrance surface dose (ESD) and the image quality figure inverse (IQFInv). Pearson correlation and regression was used to analyze the influence of AGD on IQFInv. Paired sample t-test was used to analyze the influence of different target-filters on IQFInv and AGD. Results AGD had a positive correlation with IQFInv (r=0.806-0.953, P<0.05). For the phantom of 0.1 mm aluminium, when the tube current was fixed at 100 mAs or the tube voltage was fixed at 28 kVp, AGD and IQFInv had statistically significant difference for two target-filters(t=3.162-8.028, P<0.05). For the phantom with 0.2 mm aluminium, when the tube current was fixed at 100 mAs under different tube voltage, AGD and IQFInv had statistically significant difference for two target-filters(t=4.768-8.028, P<0.05); when tube voltage was fixed at 28 kVp under different tube current, AGD had statistically significant difference for two target-filters(t=7.730, P<0.05), while there was no statistical difference in IQFInv(P>0.05). In addition, when tube current was 100 mAs, IQFInv had statistically significant difference for two phantoms in W-Rh(t=2.345, P<0.05). Conclusions W-Rh target-filter combination can achieve lower radiation dose under the guarantee of the image quality compared with Mo-Rh target-filter combination. At the same tube current, W-Rh target-filter combination can provide a better image quality under a relatively high tube voltage.