Algorithmic scatter correction in dual-energy digital mammography.
Algorithmic scatter correction in dual-energy digital mammography.
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DOI：
10.1118/1.4826173
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发表时间：
2013-11
期刊：
影响因子：
3.8
通讯作者：
Xi Chen;R. Nishikawa;Suk-tak Chan;Beverly A. Lau;Lei Zhang;X. Mou
中科院分区：
文献类型：
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作者：
Xi Chen;R. Nishikawa;Suk-tak Chan;Beverly A. Lau;Lei Zhang;X. Mou
小钙化往往是乳腺癌的最早期和主要标志。双能量数字乳腺X射线摄影（DEDM）被认为是一种有前途的技术，以提高钙化的可检测性，因为它可以用来抑制脂肪和乳腺腺体组织之间的对比度。X射线散射导致DEDM图像的错误计算。虽然针孔阵列插值法可以估计散射辐射，但它需要额外的曝光来测量散射并应用校正。本工作的目的是设计一种算法方法，散射校正在DEDM没有额外的曝光。方法基于散射辐射的空间变异性小和乳腺X线照片中的大部分像素为非钙化像素的知识，提出了一种用于DEDM的散射校正方法。在DEDM计算中估计散射分数，并使用测量的散射分数从图像中去除散射。该散射校正方法是在一个商业化的全视野数字乳腺摄影系统与乳腺组织等效体模和钙化体模。在该系统上实现了针孔阵列插值散射校正方法。两种方法的幻影结果进行了介绍和讨论。作者比较了三种DE钙化图像中的背景DE钙化信号和钙化的对比噪声比（CNR）：未进行散射校正的图像、使用针孔阵列插值方法进行散射校正的图像和使用作者算法方法进行散射校正的图像。结果作者的研究结果表明，得到的背景DE钙化信号可以减少。采用本文提出的算法，将散射不校正的背景DE钙化信号的均方根值从1962 μ m降低到194 μ m。通过算法方法，使用散射未校正数据的背景DE钙化信号的范围减少了58%，使用散射校正数据。通过散射校正算法和去噪，最小可见钙化尺寸可以从380 μ m减小到280 μ m。结论：当对图像应用所提出的算法散射校正时，可以减少所得到的背景DE钙化信号，并且可以提高钙化的CNR。该方法具有与针孔阵列插值法相似甚至更好的散射校正性能，而且该方法使用方便，不需要对患者进行额外的曝光。虽然所提出的散射校正方法是有效的，它是通过一个5厘米厚的模型与钙化和均匀的背景进行验证。该方法应在结构化背景上进行测试，以更准确地衡量有效性。
PURPOSE Small calcifications are often the earliest and the main indicator of breast cancer. Dual-energy digital mammography (DEDM) has been considered as a promising technique to improve the detectability of calcifications since it can be used to suppress the contrast between adipose and glandular tissues of the breast. X-ray scatter leads to erroneous calculations of the DEDM image. Although the pinhole-array interpolation method can estimate scattered radiations, it requires extra exposures to measure the scatter and apply the correction. The purpose of this work is to design an algorithmic method for scatter correction in DEDM without extra exposures. METHODS In this paper, a scatter correction method for DEDM was developed based on the knowledge that scattered radiation has small spatial variation and that the majority of pixels in a mammogram are noncalcification pixels. The scatter fraction was estimated in the DEDM calculation and the measured scatter fraction was used to remove scatter from the image. The scatter correction method was implemented on a commercial full-field digital mammography system with breast tissue equivalent phantom and calcification phantom. The authors also implemented the pinhole-array interpolation scatter correction method on the system. Phantom results for both methods are presented and discussed. The authors compared the background DE calcification signals and the contrast-to-noise ratio (CNR) of calcifications in the three DE calcification images: image without scatter correction, image with scatter correction using pinhole-array interpolation method, and image with scatter correction using the authors' algorithmic method. RESULTS The authors' results show that the resultant background DE calcification signal can be reduced. The root-mean-square of background DE calcification signal of 1962 μm with scatter-uncorrected data was reduced to 194 μm after scatter correction using the authors' algorithmic method. The range of background DE calcification signals using scatter-uncorrected data was reduced by 58% with scatter-corrected data by algorithmic method. With the scatter-correction algorithm and denoising, the minimum visible calcification size can be reduced from 380 to 280 μm. CONCLUSIONS When applying the proposed algorithmic scatter correction to images, the resultant background DE calcification signals can be reduced and the CNR of calcifications can be improved. This method has similar or even better performance than pinhole-array interpolation method in scatter correction for DEDM; moreover, this method is convenient and requires no extra exposure to the patient. Although the proposed scatter correction method is effective, it is validated by a 5-cm-thick phantom with calcifications and homogeneous background. The method should be tested on structured backgrounds to more accurately gauge effectiveness.