1. A method of determining material composition of a portion of an animal body, the method comprising: capturing a series of digital radiographic images of the portion of the animal body using an x-ray beam; determining a phase shift magnitude that occurred in the portion of the animal body using the captured radiographic images of the portion of the animal body; generating a differential phase shift image of the portion of the animal body; generating an integrated phase image of the portion of the animal body; and generating and displaying a radiographic image of the portion of the animal body including separately displaying within the radiographic image of the portion of the animal body a first type soft tissue and a second type soft tissue inside the portion of the animal body based on a combination of the differential phase shift image and the integrated phase image.