Dual-energy digital mammography for calcification imaging: noise reduction techniques.
Dual-energy digital mammography for calcification imaging: noise reduction techniques.
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DOI：
10.1088/0031-9155/53/19/010
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发表时间：
2008-10-07
影响因子：
3.5
通讯作者：
Shaw CC
中科院分区：
文献类型：
--
作者：
Kappadath SC;Shaw CC
我们之前已经开发了一种双能量数字乳腺X射线摄影（DEDM）技术，用于使用市售平板数字乳腺X射线摄影系统在全视野成像条件下进行钙化成像。虽然双能量成像可以抑制组织结构背景对钙化点的遮蔽，但它也增加了DE图像中的固有噪声。在这里，我们报告三种不同的降噪技术对DE钙化图像的影响：一个简单的平滑（boxcar）滤波器应用于DE图像，一个中值滤波器应用于HE图像之前的DE图像的计算和适应的Kalender的相关降噪（KNR）技术DEDM。我们比较了不同的降噪技术，通过评估其对DE钙化图像的影响，5 cm厚的乳房组织等效板，连续变化的腺体组织比例叠加各种大小的碳酸钙晶体，模拟钙化。通过比较DE钙化图像背景区域（不存在钙化）中的均方根信号和DE钙化图像中钙化的对比噪声比（CNR），对不同降噪技术进行评价。在本研究评价的不同降噪技术中，发现KNR方法在降低图像噪声和增加钙化可见性（或CNR）方面最有效，紧随其后的是HE中值滤波技术。虽然简单的平滑（矩形波串）滤波器减少了噪声，但它并没有改善钙化的可见性。假设CNR阈值为4，采用HE中值滤波器和KNR技术，在筛查乳腺X线摄影剂量下，在平滑变化的背景上，DEDM的可见钙化阈值大小估计为约250 μm。使用动物组织体模的DE图像验证了基于体模研究的降噪技术的DE图像质量，该体模由叠加在更真实组织结构上的钙化组成。
We have previously developed a dual-energy digital mammography (DEDM) technique for calcification imaging under full-field imaging conditions using a commercially available flat-panel based digital mammography system. Although dual-energy (DE) imaging could suppress the obscuration of calcifications by tissue-structure background, it also increases the intrinsic noise in the DE images. Here we report on the effects of three different noise reduction techniques on DE calcification images: a simple smoothing (boxcar) filter applied to the DE image, a median filter applied to the HE image prior to the computation of the DE image and an adaptation of the Kalender’s correlated-noise reduction (KNR) technique for DEDM. We compared the different noise reduction techniques by evaluating their effects on DE calcification images of a 5 cm thick breast-tissue-equivalent slab with continuously varying glandular-tissue ratio superimposed with calcium carbonate crystals of various sizes that simulate calcifications. Evaluations of different noise reducing techniques were performed by comparison of the root-mean-square signal in background regions (no calcifications present) of the DE calcification images and the contrast-to-noise ratios (CNR) of the calcifications in the DE calcification images. Amongst the different noise reduction techniques evaluated in this study, the KNR method was found to be most effective in reducing the image noise and increasing the calcification visibility (or CNR), closely followed by the HE median filter technique. Although the simple smoothing (boxcar) filter reduced the noise, it did not improve calcification visibility. The visible calcification threshold size with DEDM over smoothly varying background at screening mammography doses, assuming a CNR threshold of 4, was estimated to be around 250 μm with both the HE median filter and the KNR techniques. The quality of DE images with noise reduction techniques based on phantom studies were verified with DE images of an animal-tissue phantom that consisted of calcifications superimposed over more realistic tissue structures.
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影响因子：
3.8
作者：
Vedantham, S;Karellas, A;Hendrick, RE
通讯作者：
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