Phase Contrast Imaging


Tehran University of Medical Sciences



Discovery of X-ray in 1895 by Roentgen established a new branch of medicine named as Radiology. Transmission and absorption of X-rays are main parameters to make image contrast in diagnostic radiology. Image contrast is introduced by x-ray absorption difference between two regions. However sometimes that difference is too small to get a reasonable contrast. That could lead a diagnostic failure. Scientists has been studying a variety of methods to solve abovementioned problem like phase contrast imaging especially after 1965. X-ray intraction with matter could make coherent x-ray scattering and reflected photons. Those radiations could have interferences in two types as follows:

Constructive interferences: Waves interfere

in same phases causing constructive integration of amplitudes.

Destructive interferences: Waves interfere in different phases causing reduction of the resulted amplitudes, even in full opposition those will get zero. Abovementioned amplitudes are modulated to densities that their differences make contrast. Phase contrast imaging improve the image contrast in comparison with ordinary radiology especially for soft tissues like breast, however it leaves high patient radiation dose as a big challenge.