There are two types one bounces electromagnetic waves off the body to create an image like this and the other uses backscatter technology to project low level X-ray beams over the body resulting in images like this.

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Even in this high-tech era of amazing medical tools--MRI scanners that can see deep inside the body, gamma-ray beams harnessed to zap tumors, implantable defibrillators that shock the heart to keep it pumping--surgeons still wield an old-fashioned blade to take life into their hands.

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