On the basis of the DEI’s principle

a simple experimental model is used to analyze the process and character of DEI. The peak-position image

which is recorded at the peak of the rocking curve

has higher contrast than the absorption images and can show also micro-structures inside the samples. The apparent absorption image is similar to the conventional X-ray image

while the refraction image is extraordinarily sensitive to the change of the refractive index of the sample

and can clearly display edges of organic objects having different refractive indexes. The refraction image recorded in the middle position of rocking curve has better quality than that in the toe position. Furthermore

the background of the analyzer crystal affects the quality of the DEI

but does not affect the refraction image. Therefore

the refraction image has very good reliability in distinguishing normal or disease tissues

as well as for industrial inspection.