Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China.
Proc Natl Acad Sci U S A. 2010 Aug 3;107(31):13576-81. doi: 10.1073/pnas.1003198107. Epub 2010 Jul 19.
Phase sensitive X-ray imaging methods can provide substantially increased contrast over conventional absorption-based imaging and therefore new and otherwise inaccessible information. The use of gratings as optical elements in hard X-ray phase imaging overcomes some of the problems that have impaired the wider use of phase contrast in X-ray radiography and tomography. So far, to separate the phase information from other contributions detected with a grating interferometer, a phase-stepping approach has been considered, which implies the acquisition of multiple radiographic projections. Here we present an innovative, highly sensitive X-ray tomographic phase-contrast imaging approach based on grating interferometry, which extracts the phase-contrast signal without the need of phase stepping. Compared to the existing phase-stepping approach, the main advantages of this new method dubbed "reverse projection" are not only the significantly reduced delivered dose, without the degradation of the image quality, but also the much higher efficiency. The new technique sets the prerequisites for future fast and low-dose phase-contrast imaging methods, fundamental for imaging biological specimens and in vivo studies.
相敏 X 射线成象方法可提供比传统吸收基成象方法大得多的对比度，因此可以获得新的、否则无法获得的信息。在硬 X 射线相成象中使用光栅作为光学元件克服了一些妨碍相衬在 X 射线射线照相术和层析术中更广泛应用的问题。到目前为止，为了从具有光栅干涉仪检测到的其他贡献中分离出相位信息，已经考虑了相位步进方法，这意味着需要获取多个射线照相投影。在这里，我们提出了一种基于光栅干涉的创新的、高灵敏度的 X 射线层析相衬成象方法，该方法无需相位步进即可提取相衬信号。与现有的相位步进方法相比，这种新方法（称为“反向投影”）的主要优点不仅是显著降低了所传递的剂量，而不会降低图像质量，而且效率也大大提高。该新技术为未来的快速和低剂量相衬成象方法奠定了基础，这对于生物标本和体内研究的成象是至关重要的。
