Med Phys. 2012 Jul;39(7):4239-44. doi: 10.1118/1.4729838.
The high breast density is one of the biggest risk factors for breast cancer. Identifying patient having persistent high breast density is important for breast cancer screening and prevention. In this work the authors propose for the first time an x-ray phase-shifts-based method of breast density measurement.
When x ray traverses the breast, x ray gets not only its intensity attenuated but also its phase shifted. Studying the x-ray phase-shifts generated by the breast tissues, we derived a general formula for determining the volumetric breast density from the breast phase map. The volumetric breast density is reconstructed by retrieving the breast phase map from just a single phase-sensitive projection of the breast, through the use of an innovative phase retrieval method based on the phase-attenuation duality. In order to numerically validate this phase-shifts-based method for measuring the volumetric breast density, the authors performed computer simulations with a digitally simulated anthropomorphic breast phantom.
Using the proposed phase-shifts-based method, we reconstructed the breast phantom's volumetric breast density, which differs from the phantom's intrinsic breast density by only 0.06%. In the presence of noises in the projection image, the reconstructed volumetric breast density differs from the phantom's intrinsic breast density by only 1.79% for a projection signal-to-noise-ratio (SNR) of 34. The error in reconstructed breast density is further reduced to 1.61% and 1.55% for SNR = 68 and SNR = 134, respectively, achieving good accuracies in the breast density determination.
The authors proposed an x-ray phase-shifts-based method of measuring the volumetric breast density. The simulation results numerically validated the proposed method as a novel method of breast density measurement with good accuracies.
高乳房密度是乳腺癌的最大风险因素之一。确定持续存在高乳房密度的患者对于乳腺癌筛查和预防非常重要。在这项工作中，作者首次提出了一种基于 X 射线相移的乳房密度测量方法。
当 X 射线穿过乳房时，X 射线不仅会衰减其强度，还会改变其相位。通过研究乳房组织产生的 X 射线相移，我们从乳房相位图中推导出了一种确定体积乳房密度的通用公式。通过使用基于相位衰减对偶性的创新相位恢复方法，从乳房的单个相敏投影中检索乳房相位图，重建体积乳房密度。为了数值验证这种基于相移的测量体积乳房密度的方法，作者使用数字模拟的人体乳房模型进行了计算机模拟。
使用提出的基于相移的方法，我们重建了乳房模型的体积乳房密度，与模型的固有乳房密度仅相差 0.06%。在投影图像存在噪声的情况下，对于 SNR = 34 的投影信号噪声比，重建的体积乳房密度与模型的固有乳房密度相差仅 1.79%。对于 SNR = 68 和 SNR = 134，重建的乳房密度误差分别进一步降低到 1.61%和 1.55%，在乳房密度确定方面具有良好的准确性。
作者提出了一种基于 X 射线相移的测量体积乳房密度的方法。模拟结果数值验证了该方法作为一种具有良好准确性的新型乳房密度测量方法的有效性。
