 Phase @-@ contrast X @-@ ray imaging ( Fig . 26 ) refers to a variety of techniques that use phase information of a coherent x @-@ ray beam to image soft tissues . ( For an elementary discussion , see Phase @-@ contrast x @-@ ray imaging ( introduction ) . For a more in @-@ depth review , see Phase @-@ contrast X @-@ ray imaging . ) It has become an important method for visualizing cellular and histological structures in a wide range of biological and medical studies . There are several technologies being used for x @-@ ray phase @-@ contrast imaging , all utilizing different principles to convert phase variations in the x @-@ rays emerging from an object into intensity variations . These include propagation @-@ based phase contrast , talbot interferometry , moiré @-@ based far @-@ field interferometry , refraction @-@ enhanced imaging , and x @-@ ray interferometry . These methods provide higher contrast compared to normal absorption @-@ contrast x @-@ ray imaging , making it possible to see smaller details . A disadvantage is that these methods require more sophisticated equipment , such as synchrotron or <unk> x @-@ ray sources , x @-@ ray optics , or high resolution x @-@ ray detectors . 
