A discretely addressable large-area X-ray system is provided. The large-area X-ray system can output a uniform flux of X-rays over a large area using discrete addressing operation of transistors connected to cathodes of electron emitters. Thus, when applied to a medical device, the system can minimize damage inflicted upon the human body because it enables effective imaging of only a desired specific portion of the body. Furthermore, the large-area X-ray system can be simply implemented by current switching using transistors. Thus, the system can be very easily applied to other applications.