Crystal-Based X-ray Interferometry and Its Application to Phase-Contrast X-ray Imaging, Zeff Imaging, and X-ray Thermography

Crystal-based X-ray interferometry (CXI) detects X-ray phase shifts by using the superposition of waves, and its sensitivity is the highest among the other X-ray phase-detecting methods. Therefore, phase-contrast X-ray imaging (PCXI) using CXI has the highest density resolution among the PCXI methods and enables fine, non-destructive observation with a density resolution below sub-mg/cm(3). It has thus been applied in a wide range of fields, including biology, medicine, geology, and industry, such as visualization of the testis and brains of aged rats with tumors, human embryos at each Carnegie stage, air hydrates in old Antarctic ice, and ion distribution in electrolytes. Novel imaging methods have also been developed to take advantage of its high sensitivity, such as visualization of the effective atomic number (Z(eff)) and the three-dimensional temperature of samples. This article reviews the principles and history of PCXI and crystal-based X-ray interferometers, as well as a CXI system using synchrotron radiation and its potential applications from biomedical to industrial.