An X-ray image is like a photograph taken in the dark with a very short flash: anything that moves comes out blurred. Conventional X-ray detectors are large arrays of millions of pixels, and by the time they read out one frame, the next is already missed. For a spinning turbine or a beating heart, such sluggishness is a death sentence.

A team of researchers sidestepped this problem by ditching the array altogether. Instead, they use a single, highly sensitive detector that captures the entire X-ray flux at once. In front of the object, they place a mask with a random pattern of opaque and transparent areas. The mask spins rapidly, the pattern changes, and the detector records a series of numbers, as if you were looking at the world through flickering shadows. Then a computer, knowing which patterns were present at each moment, reconstructs an image from those numbers. This approach is called ghost imaging: the image is born not from a direct snapshot but from correlations between patterns and signals.

Previously, ghost imaging for X-rays was too slow: each frame took minutes. The new method with a fast mask speeds up imaging to 200 frames per second, and details as small as 225 micrometers, thinner than a human hair, remain discernible. For the first time, clear X-ray video of moving objects has been captured at such speed.

Now you can look inside a running aircraft engine and see how the compressor blades vibrate at full throttle. Or take a chest X-ray while the patient breathes, without asking them to hold still. The method opens the door to X-ray "cinema" where previously there were only static images.