送交者: boxer 于 2005-6-28, 12:14:42:
回答: 那个MRI， CAT 还有PET SCAN 由 cornbug 于 2005-6-28, 11:04:27:
MRI using magnetic field. It measures the response(resonance) of Hydrogen to the magnetic field.
Both x-ray and positron are not good stuff. In theory, the size of a totally coherent beam is controlled by the aperture size. However, the x-ray beam from a x-ray tube is pretty wide. It penerates your body and the energy kills your cell wherever it goes. To my limited understanding, some radioactive materials have to be put into your body in order to use positron, which combines with the electrons in your body, release energy and do damage on your cell.
如果用分子扫描的话，人大慨要被切断？This is not correct. I guess it kills cells only through breaking the bond. I don't think it could cause mass loss.