数字乳腺X线摄影平均腺体剂量与腺体密度及压迫厚度的关系研究

摘要

目的：分析数字乳腺X线摄影平均腺体剂量（AGD）与乳腺密度及压迫厚度之间的关系，探讨乳腺密度、压迫厚度对AGD的影响。方法回顾性分析2008年10月在我院就诊的600例女性病人的600幅单侧乳腺头尾位影像资料，均采用自动曝光模式。按照BI-RADS标准将腺体分为<25%、25%～50%、51%～75%和>75%共4型，每型150例，每型按照乳腺压迫厚度又分为<35 mm、35～50 mm 和51～64 mm 组，每组各50例。采用 SPSS 17.0统计学软件对不同压迫厚度、腺体密度的病人的 AGD 进行单因素方差分析，对不同压迫厚度、腺体密度与AGD间的关系采用Spearman相关性分析。结果不同压迫厚度、腺体密度的病人，其AGD的差异均具有统计学意义（P=0.000），且AGD随着乳腺压迫厚度和腺体密度的增加而增加；同时，腺体密度与AGD的相关性（r=0.674， P=0.000）高于压迫厚度（r=0.456，P=0.000）。结论乳腺密度及压迫厚度与数字乳腺X线摄影AGD关系密切，有利于在手动曝光模式或某些特殊情况下根据乳腺类型（腺体密度、厚度等）选择适当的曝光参数，以最低的辐射剂量获得最优质的影像，减少病人的辐射损伤。%Objective To investigate the effect of mammographic density and compression thickness on average glandular dose (AGD). Methods Unilateral breast craniocaudal imaging data and adopt automatic exposure mode from 600 female patients which were collected in October 2008 in our hospital were retrospectively analyzed. According to the BI-RADS standard, the gland densities were divided into four types, including<25%, 25%~50%, 51%~75%, and>75%, with 150 cases each. Each type was divided into < 35 mm, 35~50 mm, and 51~64 mm, according to the breast compression thickness, 50 cases in each group. SPSS 17.0 was used to test the differences in AGD between types/groups of compression thickness and gland density with single factor analysis of variance. Spearman coefficient was used to test the correlation between different gland density, compression thickness, and AGD. Results AGD values were statistically significant different between types/groups of compression thickness and gland density(P<0.001). The values of AGD were increased when increasing breast compression thickness and glandular density. The gland density had greater influence on AGD (r=0.674, P<0.001) than compression thickness did (r=0.456, P<0.001). Conclusion Breast density and compression thickness have close relationship with the AGD in digital mammography. In manual exposure mode or some special circumstances, exposure parameters should be adjusted based on the breast type (gland density and thickness) to reduce the radiation injury without compromising image quality.