Capturing Curved Objects Through X-rays

A flexible X-ray created by embedding nanocrystals in rubber is paving the way for the ultra-high-resolution imaging of curved objects.

AsianScientist (Jul. 13, 2021) – Scientists from Singapore have developed an ultra-high-resolution X-ray capable of imaging three-dimensional (3D) objects. Their findings were published in Nature.

Though X-rays may be a routine part of our annual check-ups, the imaging technology has a long way to go when it comes to capturing curved 3D objectives at a high resolution. After all, in current machines, the X-ray detector is a flat panel, with each pixel having its own integrated circuit. This makes the pixels bulky and prone to overheating, limiting the detector’s resolution and its ability to capture images of curved objects.

To overcome these limitations, chemists from the National University of Singapore (NUS), Hong Kong Polytechnic University and Fuzhou University have turned to X-ray-trapping nanocrystals.

Led by Professor Liu Xiaogang, the team created special nanocrystals that emit light after X-ray exposure. This phenomenon, called persistent radioluminescence, is also responsible for the greenish glow of clock faces in the dark.

The team achieved this by introducing atoms of the rare-earth element terbium into tiny crystals of a substance called sodium lutetium fluoride—a process known as doping. These modified nanocrystals were then embedded into silicone rubber, creating a highly flexible X-ray detector that can be wrapped around 3D objects.

According to the authors, the resulting detector gives a high resolution finer than human hair, with terbium-doped nanocrystals having enhanced sensitivity to X-rays.

By displacing atoms and generating electrons that “hop” slowly throughout the crystal towards the terbium ions, the X-rays give rise to prolonged luminescence that last over two weeks. As long as the nanocrystals remain luminescent, the recorded image can be retrieved anytime via heating.

Beyond healthcare, the new X-ray detector could also be deployed to identify defects in electronics, authenticate valuable works of art and examine archaeological objects at a microscopic scale.

“Our reported technology may provide a much-needed solution for imaging highly curved 3D objects and enable the development of point-of-care X-ray detectors and flexible X-ray mammography devices,” concluded Liu.

The article can be found at: Ou et al. (2021) High-resolution X-ray Luminescence Extension Imaging.


Source: National University of Singapore; Photo: Ou Xiangyu.
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