Carl E Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, NC 27705, USA.
Phys Med Biol. 2011 Oct 7;56(19):6359-78. doi: 10.1088/0031-9155/56/19/013. Epub 2011 Sep 9.
Dual-energy contrast-enhanced breast tomosynthesis is a promising technique to obtain three-dimensional functional information from the breast with high resolution and speed. To optimize this new method, this study searched for the beam quality that maximized image quality in terms of mass detection performance. A digital tomosynthesis system was modeled using a fast ray-tracing algorithm, which created simulated projection images by tracking photons through a voxelized anatomical breast phantom containing iodinated lesions. The single-energy images were combined into dual-energy images through a weighted log subtraction process. The weighting factor was optimized to minimize anatomical noise, while the dose distribution was chosen to minimize quantum noise. The dual-energy images were analyzed for the signal difference to noise ratio (SdNR) of iodinated masses. The fast ray-tracing explored 523 776 dual-energy combinations to identify which yields optimum mass SdNR. The ray-tracing results were verified using a Monte Carlo model for a breast tomosynthesis system with a selenium-based flat-panel detector. The projection images from our voxelized breast phantom were obtained at a constant total glandular dose. The projections were combined using weighted log subtraction and reconstructed using commercial reconstruction software. The lesion SdNR was measured in the central reconstructed slice. The SdNR performance varied markedly across the kVp and filtration space. Ray-tracing results indicated that the mass SdNR was maximized with a high-energy tungsten beam at 49 kVp with 92.5 µm of copper filtration and a low-energy tungsten beam at 49 kVp with 95 µm of tin filtration. This result was consistent with Monte Carlo findings. This mammographic technique led to a mass SdNR of 0.92 ± 0.03 in the projections and 3.68 ± 0.19 in the reconstructed slices. These values were markedly higher than those for non-optimized techniques. Our findings indicate that dual-energy breast tomosynthesis can be performed optimally at 49 kVp with alternative copper and tin filters, with reconstruction following weighted subtraction. The optimum technique provides best visibility of iodine against structured breast background in dual-energy contrast-enhanced breast tomosynthesis.
双能对比增强乳腺断层合成术是一种很有前途的技术，它可以在高分辨率和高速的情况下从乳房获得三维功能信息。为了优化这种新方法，本研究寻找了在质量检测性能方面使图像质量最大化的射线质量。采用快速射线追踪算法对数字断层合成系统进行建模，该算法通过跟踪穿过包含碘化物病变的体素化解剖乳房体模的光子来创建模拟投影图像。通过加权对数减法过程将单能图像组合成双能图像。优化权重因子以最小化解剖噪声，同时选择剂量分布以最小化量子噪声。对碘化物肿块的信噪比（SdNR）进行双能图像分析。快速射线追踪探索了 523776 种双能组合，以确定哪种组合能产生最佳的肿块 SdNR。射线追踪结果使用基于硒的平板探测器的乳腺断层合成系统的蒙特卡罗模型进行了验证。从我们的体素化乳房体模获得了恒定的总腺体剂量的投影图像。使用加权对数减法组合投影，并使用商业重建软件进行重建。在中央重建切片中测量病变 SdNR。SdNR 性能在 kVp 和滤波空间上有很大差异。射线追踪结果表明，在高能钨射线 49 kVp 下使用 92.5 µm 铜过滤和在低能钨射线 49 kVp 下使用 95 µm 锡过滤时，肿块 SdNR 最大化。这一结果与蒙特卡罗的发现一致。这种乳腺摄影技术在投影中产生了 0.92±0.03 的质量 SdNR，在重建切片中产生了 3.68±0.19 的质量 SdNR。这些值明显高于非优化技术的值。我们的研究结果表明，在替代铜和锡滤过器的情况下，双能乳腺断层合成术可以在 49 kVp 下进行最佳优化，随后进行加权减法重建。最佳技术在双能对比增强乳腺断层合成术中提供了碘对结构背景乳腺的最佳可见度。
