Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden.
Med Phys. 2012 May;39(5):2431-7. doi: 10.1118/1.3694105.
To investigate the visibility of simulated lesions in digital breast tomosynthesis (BT) image volumes compared with 2D digital mammography (DM).
Simulated lesions (masses and microcalcifications) were added to images of the same women acquired on a DM system (Mammomat Novation, Siemens) and a BT prototype. The same beam quality was used for the DM and BT acquisitions. The total absorbed dose resulting from a 25-projection BT acquisition and reconstruction (BT(25)) was approximately twice that of a single DM view. By excluding every other projection image from the reconstruction (BT(13)), approximately the same dose as in DM was effected. Simulated microcalcifications were digitally added with varying contrast to the DM and BT images. Simulated masses with 8 mm diameter were also added to BT images. A series of 4-alternative forced choice (4AFC) human observer experiments were conducted. Four medical physicists participated in all experiments, each consisting of 60 trials per experimental condition. The observers interpreted the BT image volumes in cine-mode at a fixed image sequence speed. The required threshold contrast (S(t)) to achieve a detectability index (d') of 2.5 (i.e., 92.5% correct decisions) was determined.
The S(t) for mass detection in DM was approximately a factor of 2 higher than required in BT indicating that the detection of masses was improved under BT conditions compared to DM. S(t) for microcalcification detection was higher for BT than for DM at both BT dose levels (BT(25) and BT(13)), with a statistically significant difference in S(t) between DM and BT(13). These results indicate a dose-dependent decrease in detection performance in BT for detection of microcalcifications.
In agreement with previous investigations, masses of size 8 mm can be detected with less contrast in BT than in DM indicating improved detection performance for BT. However, for the investigated microcalcifications, the results of this study indicate potentially worse performance for BT than for DM at the same dose level.
与二维数字乳腺摄影术（DM）相比，研究数字乳腺断层合成（BT）图像体积中模拟病变的可视性。
在 DM 系统（西门子 Mammomat Novation）和 BT 原型上获取同一女性的图像，添加模拟病变（肿块和微钙化）。DM 和 BT 采集使用相同的射线质。从重建中排除 BT（25）的每两个投影图像（BT（13）），可实现与 DM 相同的剂量。模拟微钙化用不同的对比度数字添加到 DM 和 BT 图像中。还将 8 毫米直径的模拟肿块添加到 BT 图像中。进行了一系列四择一强迫选择（4AFC）人类观察者实验。四名医学物理学家参加了所有实验，每个实验条件下包含 60 次试验。观察者在固定的图像序列速度下以电影模式解释 BT 图像体积。确定达到检出率（d'）为 2.5（即 92.5%正确决策）所需的阈值对比度（S(t)）。
DM 中肿块检测的 S(t)大约是 BT 所需的两倍，表明与 DM 相比，BT 条件下肿块的检测得到改善。在两种 BT 剂量水平（BT（25）和 BT（13））下，BT 中的微钙化检测的 S(t)均高于 DM，BT（13）与 DM 之间的 S(t)存在统计学差异。这些结果表明在 BT 中检测微钙化的检测性能随剂量呈下降趋势。
与先前的研究一致，8 毫米大小的肿块在 BT 中可以用比 DM 更少的对比度检测到，表明 BT 的检测性能有所提高。然而，对于研究中的微钙化，本研究的结果表明，在相同的剂量水平下，BT 的性能可能比 DM 差。
