Medical imaging has come a long way since 1895, when german physicist Wilhelm Conrad Rntgen observed strange flickers cast by his cathode-ray instruments. Within months, Rntgen had used the mysterious "x-rays," as he called them, to produce an image of the bones of his wife's hand, revolutionizing medicine. For the first time, physicians could peek inside the body without cutting it open or probing an orifice. Today they can practically image our thoughts.

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