Stephanie E. Pierce2014-05-06 2:33 PM

 同步微断层大型密集化石成像样品吸收的同质化 Homogenization of sample absorption for the imaging of large and dense fossils with synchrotron microtomography

论文摘要

传播相衬同步辐射显微层析(PPC- SRμCT)已被证明用来研究化石是非常适合的。由于化石的埋藏保存,大小,形状和密度范围十分广泛,X射线计算机断层扫描协议正为此不断发展和完善。在此我们提出了结合过滤高能量多色光束和长距PPC-SRμCT(样品检测:4-16米)的1-h过程以及正规化吸收曲线的衰减协议(已在13cm厚,5.242克厘米-3处局部密集的样本中进行检测但能适用于20厘米厚样本中)。这种方法提供了高品质成像效果,这显示出了相对于未含衰减协议的明显传输,对比和信号噪声比中所获图像结果的显著改善。衰减协议包括在与U形铝分析器相关的填充有铝或玻璃球管中浸泡样品。因此这种技术提供了对用于层析成像重建检测器的较大动态范围的访问。此协议使得射束硬化人工制品均质化,从而使其能在传统μCT扫描仪下进行有效使用。


Abstract

Propagation phase-contrast synchrotron radiation microtomography (PPC-SRμCT) has proved to be very successful for examining fossils. Because fossils range widely in taphonomic preservation, size, shape and density, X-ray computed tomography protocols are constantly being developed and refined. Here we present a 1-h procedure that combines a filtered high-energy polychromatic beam with long-distance PPC-SRμCT (sample to detector: 4–16 m) and an attenuation protocol normalizing the absorption profile (tested on 13-cm-thick and 5.242 g cm−3 locally dense samples but applicable to 20-cm-thick samples). This approach provides high-quality imaging results, which show marked improvement relative to results from images obtained without the attenuation protocol in apparent transmission, contrast and signal-to-noise ratio. The attenuation protocol involves immersing samples in a tube filled with aluminum or glass balls in association with a U-shaped aluminum profiler. This technique therefore provides access to a larger dynamic range of the detector used for tomographic reconstruction. This protocol homogenizes beam-hardening artifacts, thereby rendering it effective for use with conventional μCT scanners.

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Stephanie E. Pierce

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