Researchers from the Chinese Academy of Sciences and Shanghai Jiao Tong University have developed a tabletop X-ray ghost imaging technique capable of capturing high-speed, two-dimensional images of moving objects at rates of up to 200 frames per second.
The method, published in the peer-reviewed journal Communications Physics on August 15, is designed to address limitations associated with conventional X-ray imaging when inspecting dynamic objects. The researchers said the technique could have applications in medical imaging and non-destructive imaging of moving mechanical components.
From a non-destructive testing (NDT) perspective, the technology could support the inspection of dynamic components such as rotating aircraft engines, where conventional X-ray imaging can experience motion blur and gaps between frames.
“In contrast to other available X-ray imaging techniques for moving objects, our method can be implemented with a conventional tabletop X-ray source,” the team said in the paper. “The set-up is simple, relatively inexpensive and easy to operate.”
Unlike conventional X-ray imaging, which directly records radiation transmitted through an object using a detector or film, X-ray ghost imaging uses an indirect reconstruction process. X-rays pass through a patterned filter and are measured by a single-pixel detector that records the total intensity reaching the detector. A computer then compares the detected intensity with the known patterns to reconstruct an image.
The researchers noted that conventional X-ray ghost imaging has faced limitations for dynamic applications because the patterned filter typically needs to change after each exposure, resulting in long acquisition times.
The new approach addresses this limitation by using a rotating filter or mask containing small patterns that change rapidly as the mask rotates. This enables faster acquisition and reconstruction of images from moving objects.
“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.
In experiments, the researchers used the system to image a rotating copper disk containing stencilled letters. The system successfully reconstructed the letters while the disk was rotating, although image quality decreased as rotational speed increased.
A comparison with a conventional X-ray camera showed that the ghost imaging system produced lower overall image quality but was capable of continuously recording the motion of the letters. The conventional camera generated sharper images when the object was stationary but experienced motion blur and frame gaps when the object was moving.
The researchers identified the rotation speed of the patterned mask and the sampling frequency of the detection system as key factors limiting imaging speed. Improvements in both areas could enable faster acquisition and higher-quality imaging.
The team also highlighted the potential of the approach in situations where conventional array-based cameras are difficult or expensive to deploy.
“Notably, our proposed method is not limited to any wavelength but would be particularly suitable for situations where array cameras are cumbersome, extremely expensive and difficult to maintain,” the team said.
The researchers said the technique could offer a simpler and potentially lower-radiation-dose approach for dynamic X-ray imaging, with potential applications spanning medical imaging and NDT of moving mechanical components.
