Department of Diagnostic Physics, Oslo University Hospital, Oslo, Norway. Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
Phys Med Biol. 2018 Jan 25;63(3):035006. doi: 10.1088/1361-6560/aaa614.
The main purpose was to compare average glandular dose (AGD) for same-compression digital mammography (DM) and digital breast tomosynthesis (DBT) acquisitions in a population based screening program, with and without breast density stratification, as determined by automatically calculated breast density (Quantra). Secondary, to compare AGD estimates based on measured breast density, air kerma and half value layer (HVL) to DICOM metadata based estimates. AGD was estimated for 3819 women participating in the screening trial. All received craniocaudal and mediolateral oblique views of each breasts with paired DM and DBT acquisitions. Exposure parameters were extracted from DICOM metadata. Air kerma and HVL were measured for all beam qualities used to acquire the mammograms. Volumetric breast density was estimated using Quantra. AGD was estimated using the Dance model. AGD reported directly from the DICOM metadata was also assessed. Mean AGD was 1.74 and 2.10 mGy for DM and DBT, respectively. Mean DBT/DM AGD ratio was 1.24. For fatty breasts: mean AGD was 1.74 and 2.27 mGy for DM and DBT, respectively. For dense breasts: mean AGD was 1.73 and 1.79 mGy, for DM and DBT, respectively. For breasts of similar thickness, dense breasts had higher AGD for DM and similar AGD for DBT. The DBT/DM dose ratio was substantially lower for dense compared to fatty breasts (1.08 versus 1.33). The average c-factor was 1.16. Using previously published polynomials to estimate glandularity from thickness underestimated the c-factor by 5.9% on average. Mean AGD error between estimates based on measurements (air kerma and HVL) versus DICOM header data was 3.8%, but for one mammography unit as high as 7.9%. Mean error of using the AGD value reported in the DICOM header was 10.7 and 13.3%, respectively. Thus, measurement of breast density, radiation dose and beam quality can substantially affect AGD estimates.
目的是比较基于人群的筛查计划中同一压缩数字乳腺摄影术（DM）和数字乳腺断层合成术（DBT）采集的平均腺体剂量（AGD），并比较自动计算的乳腺密度（Quantra）确定的有和无乳腺密度分层的情况下的 AGD。其次，比较基于测量的乳腺密度、空气比释动能和半价层（HVL）以及基于 DICOM 元数据的 AGD 估计值。对参加筛查试验的 3819 名女性进行了 AGD 估计。所有女性均接受了双侧 craniocaudal 和 mediolateral 斜位 DM 和 DBT 采集。从 DICOM 元数据中提取曝光参数。测量了所有用于获取乳房 X 线照片的射线质的空气比释动能和 HVL。使用 Quantra 估计容积乳腺密度。使用 Dance 模型估计 AGD。还评估了直接从 DICOM 元数据报告的 AGD。DM 和 DBT 的平均 AGD 分别为 1.74 和 2.10 mGy。DBT/DM 的平均 AGD 比值为 1.24。对于脂肪性乳房：DM 和 DBT 的平均 AGD 分别为 1.74 和 2.27 mGy。对于致密性乳房：DM 和 DBT 的平均 AGD 分别为 1.73 和 1.79 mGy。对于厚度相似的乳房，致密性乳房的 DM 平均 AGD 较高，而 DBT 的 AGD 相似。与脂肪性乳房相比，致密性乳房的 DBT/DM 剂量比明显较低（1.08 与 1.33）。平均 c 因子为 1.16。使用以前发表的多项式从厚度估计腺体，平均低估了 c 因子 5.9%。基于测量值（空气比释动能和 HVL）与 DICOM 标头数据之间的 AGD 估计值之间的平均误差为 3.8%，但对于一个乳房 X 线摄影单位，误差高达 7.9%。使用 DICOM 标题中报告的 AGD 值的平均误差分别为 10.7%和 13.3%。因此，乳腺密度、辐射剂量和射束质量的测量会极大地影响 AGD 估计值。
