Chinese Team Develops Tabletop X-Ray Method to Film Fast-Moving Objects

Researchers from the Chinese Academy of Sciences and Shanghai Jiao Tong University have developed a new tabletop X-ray ghost imaging method that captures real-time "see-through" video of fast-moving objects, according to a paper published in the peer-reviewed journal Communications Physics on August 15. The team says the technique could be used to image dynamic objects such as rotating aircraft engines or a beating heart, at a lower radiation dose and with simpler equipment than traditional X-ray video methods.

Conventional X-ray imaging shoots radiation through an object onto a detector, directly capturing an image of what absorbed it. X-ray ghost imaging instead shines X-rays through a patterned filter and records only the total intensity reaching a single-pixel detector; a computer then reconstructs the image by comparing that intensity against the known patterns. This can work at a lower radiation dose than conventional X-ray, but existing ghost-imaging methods have required very long acquisition times because the filter pattern must be changed after each exposure, making them impractical for moving objects.

The Chinese team's method instead uses a spinning filter whose tiny patterns change rapidly as it rotates, allowing much faster image acquisition -- up to 200 frames per second. The researchers tested the system on a spinning copper disk stencilled with letters: it accurately imaged the letters, though quality degraded as the disk spun faster. Compared with a traditional X-ray camera, the new system produced lower-quality individual frames but recorded the full motion continuously, while the traditional camera captured sharper still images but suffered motion blur and frame gaps during movement.

"Our method has greatly improved the [X-ray ghost imaging] speed and paves the way for X-ray imaging applications of moving objects, such as the inspection of rotating aero-engines and in vivo medical imaging," the team said, adding that the imaging speed is currently limited mainly by the spinning mask's rotation speed and the detector's sampling frequency.