Scatter correction for clinical cone beam CT breast imaging based on breast phantom studies
Scatter correction for clinical cone beam CT breast imaging based on breast phantom studies
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DOI：
10.3233/xst-2010-0280
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发表时间：
2011-01-01
影响因子：
3
通讯作者：
Conover, David
中科院分区：
文献类型：
--
作者：
Cai, Weixing;Ning, Ruola;Conover, David
在基于平板探测器的锥束CT乳腺成像(CBCTBI)系统中，散射是影响成像质量的一个重要因素。在患者研究中测量所有视角的乳房散射分布是不现实的，但有可能开发一种基于从乳房模型研究中获得的信息来估计散射分布的方法。提出了一种新的用于临床CBCTBI的散射校正方法。对三个不同大小的拟人化未压缩乳房模型的散射分布进行了深入的研究，结果表明，虽然模型的大小不同，但散射分布主要由局部乳房直径决定，乳房局部直径是乳房冠状切片垂直于乳头至胸壁方向的近似直径。因此，为了散射校正的目的，有可能建立位置乳房直径和局部散射分布之间的关系，即，散布比(SPR)和归一化散射辐射(NSR)的拟合平滑曲线。在临床CBCTBI研究中，在投影图像上采样和测量局部乳房直径后，可以根据建立的关系生成每个投影图像的散射图，并可以使用基于SPR的方法或基于NSR的方法对投影图像进行校正。体模研究和临床研究表明，SPR和NSR方法均能纠正拔火罐伪影，减少重建误差。SPR方法不会增加组织对比度或噪声，而NSR方法会增加两者。
In flat-panel detector-based cone beam CT breast imaging (CBCTBI) systems, scattering is an important factor that degrades image quality. It is not practical to measure the scattering profiles of a breast for all view angles in a patient study, but it is possible to develop a method to estimate the scattering profiles based on information acquired from breast phantom studies. A new scattering correction method is proposed for clinical CBCTBI in this study. The scattering profiles of three anthropomorphic uncompressed breast phantoms of different sizes were thoroughly investigated, and the results indicated that though phantom size differed, the scattering profiles were mainly determined by local breast diameters, which are the approximate diameters of coronal slices that are perpendicular to the nipple-to-chestwall direction. Thus for scattering correction purposes it is possible to establish a relationship between location breast diameters and local scattering profiles, namely the fitted smooth curves of scatter-to-primary ratios (SPR) and normalized scattered radiations (NSR). In clinical CBCTBI studies, after the local breast diameters are sampled and measured on projection images, the scattering image for every projection image can be generated based on the established relationship, and the projection images can be corrected using either the SPR based method or the NSR based method. Phantom studies and clinical studies showed that both the SPR and NSR methods are able to correct cupping artifacts and reduce reconstruction error. The SPR method does not increase tissue contrast or noise while the NSR method increases both.