A medical image system includes an X-ray imaging device with a Talbot or Talbot-Lau interferometer, a reconstructed image generation unit, an extraction unit, a feature value calculation unit and a determination unit. The generation unit generates, among a differential phase image, an absorption image and a small-angle scattering image, at least the differential phase image based on an image signal obtained by the X-ray imaging device imaging a joint part. The extraction unit extracts a joint cartilage region based on the differential phase image. The calculation unit analyzes the joint cartilage region to calculate a feature value indicating a joint cartilage state. The determination unit compares the feature value with a predetermined reference value and determines, based on the comparison result, into which one of predetermined scores of multiple stages the joint cartilage state falls.
