Making the invisible visible

Using x-rays scientists have learned to make the invisible visible. Since almost 100 years doctors use the difference in x-ray absorption between bones and tissue to diagonose their patients. Using modern synchrotrons it has become possible to do such imaging with much reduced side effects. The new phase contrast method uses the fact that, like visible light, x-rays are deflected when traveling through objects with different densities. This allows making small density variations visible even in weakly absorbing tissue. This novel technology may now find broad applications outside of synchrotrons. Using a specially designed grating interferometer such phase contrast imaging can now be done with ordinary x-ray tubes. The technique was first tested on an insect, but after further tests and development it may well be used for human patients. Here it may soon make invisible tumors visible and allow early therapy.

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