A system and method for imaging or treating a disease in a human or animal body. The system provides to the human or animal body a pharmaceutical carrier including one or more phosphors which are capable of emitting ultraviolet or visible light into the body and which provide x-ray contrast. The system includes one or more devices which infuse a diseased site with a photoactivatable drug and the pharmaceutical carrier, an initiation energy source comprising an x-ray or high energy source which irradiates the diseased site with at least one of x-rays, gamma rays, or electrons to thereby initiate emission of said ultraviolet or visible light into the body, and a processor programmed to at least one of 1) produce images of the diseased site or 2) control a dose of said x-rays, gamma rays, or electrons to the diseased site for production of said ultraviolet or visible light at the diseased site to activate the photoactivatable drug.