Characterization of X-ray scattering for various phantoms and clinical breast geometries using breast CT on a dedicated hybrid system.
Characterization of X-ray scattering for various phantoms and clinical breast geometries using breast CT on a dedicated hybrid system.
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DOI：
10.3233/xst-16202
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发表时间：
2017
影响因子：
3
通讯作者：
Tornai MP
中科院分区：
文献类型：
--
作者：
Shah JP;Mann SD;Tornai MP
这项研究的目的是利用专用的乳腺CT系统，使用2D波束停止阵列来物理地评估不同几何模型和预期获得的临床患者数据的散布与基色比(SPR)。包括临床上无法实现的100%腺体和100%脂肪的成分，使用三个几何上不同的模型来获取投影图像，其中填充了模拟乳房组织的液体。采用波束阻挡阵列法测量投影空间的散射度，生成散射校正后的原始图像。计算二维SPR。此外，还计算了一个新的优值因子--三维归一化散射贡献(NSC)体积。2DSPR值(0.52-1.10)主要取决于模体的几何形状，其次是由于其均匀的密度；2DSPR是低频的，在均匀填充的模体中平稳变化。临床患者数据的SPR与体模的趋势相似，但由于腺体组织的不均匀分布，SPR具有明显的偏差和高频成分。即使是最大直径的乳房，测量的患者2D SPR的最大值也是0.6。这些结果表明，随着物体几何形状和密度的变化，适度的散射分量；具有较高频率分量的3D NSC体积有助于可视化重建图像体积中的散射分布。此外，等密度、均匀填充的模体低估了异质性临床乳腺病例的SPR。这些结果为在考虑模拟时使用均匀分布的密度和不同形状的模体提供了指导。他们还清楚地表明，患者的结果可能与统一模拟模型的2D SPR有很大不同。
The purpose of this study was to utilize a dedicated breast CT system using a 2D beam stop array to physically evaluate the scatter to primary ratios (SPRs) of different geometric phantoms and prospectively acquired clinical patient data. Including clinically unrealizable compositions of 100% glandular and 100% fat, projection images were acquired using three geometrically different phantoms filled with fluids simulating breast tissue. The beam stop array method was used for measuring scatter in projection space, and creating the scatter corrected primary images. 2D SPRs were calculated. Additionally, a new figure of merit, the 3D normalized scatter contribution (NSC) volumes were calculated. The 2D SPR values (0.52–1.10) were primarily dependent on phantom geometry; a secondary dependence was due to their uniform density; 2D SPRs were low frequency and smoothly varying in the uniformly filled phantoms. SPRs of clinical patient data followed similar trends as phantoms, but with noticeable deviations and high frequency components due to the heterogeneous distribution of glandular tissue. The maximum measured patient 2D SPRs were all <0.6, even for the largest diameter breast. These results demonstrate modest scatter components with changing object geometries and densities; the 3D NSC volumes with higher frequency components help visualize scatter distribution throughout the reconstructed image volumes. Furthermore, the SPRs in the heterogeneous clinical breast cases were underestimated by the equivalent density, uniformly filled phantoms. These results provide guidance on the use of uniformly distributed density and differently shaped phantoms when considering simulations. They also clearly demonstrate that results from patients can vary considerably from 2D SPRs of uniformly simulated phantoms.