X-ray diagnostic apparatus and medical-information processing apparatus

An X-ray diagnostic apparatus, comprising:

• processing circuitry configured to
• determine, before performing contrast-enhanced imaging, a particular concentration of a contrast agent in a blood vessel included in a contrast-enhanced image to be collected, based on first reference information in which a recommended contrast in a contrast-enhanced image is associated with each region of interest to be subject to collection of the contrast-enhanced image, and on second reference information that indicates a relation among a generation condition of an X-ray, a corresponding concentration of the contrast agent, and a contrast, and
• calculate setting information of an injector to inject the contrast agent to the subject based on the determined concentration of the contrast agent.