Method and apparatus for photothermal modification of x-ray images

An x-ray image of a body can be modified by absorption of laser radiation that causes thermal gradients to be generated in portions of the body. If an object within the body has a higher optical absorption than the surrounding medium, the effect of absorption of the laser radiation is to cause the production of thermal gradients. Thermal gradients give rise to density gradients, which modify an x-ray image through changes in x-ray index of refraction at the site of the thermal gradient. The overall effect of the laser heating is to produce an x-ray contrast mechanism wherein the x-ray image becomes sensitive to differences in the optical absorption within a body. An application of the invention is for detection of tumors that are highly vascularized, using a laser operating in the near infrared.