World's smallest CT scanner fits in the palm of your hand
by Omar Kardoudi · New AtlasPicture a CT scanner and you probably imagine a donut-shaped machine the size of a small car, standing about 6.6 ft (2 m) tall and weighing several tons. Chinese researchers just built one small enough to hold in one hand.
The new device, called Xtomo-Cube, measures just 5.5 x 5.1 x 8.7 in (14 x 13 x 22 cm) – roughly the footprint of a desktop speaker – and weighs about 13 lb (6 kg). Its maker, Ruiying Detection Technology, a spinoff from the Institute of High Energy Physics at the Chinese Academy of Sciences, calls it the smallest and lightest CT system ever built.
Until now, the record for the smallest portable CT scanner belonged to a unit developed by the Fraunhofer Development Center for X-ray Technology (EZRT) in Germany, weighing 42 lb (19 kg), more than three times heavier than the Xtomo-Cube.
"This is the world's smallest CT scanner," said Liu Baodong, an engineer at the Chinese Academy of Sciences and the Ruiying's general manager. "The device can be held in one hand, and it's the smallest and lightest CT system in the world, which is why people call it the handheld CT."
CT scanners come in all sorts of shapes and sizes. Some industrial systems are truck-sized and up to three times heavier than a standard hospital scanner, while others are compact enough to wheel quickly into an operating room or small enough to sit on a countertop (like a microwave) for scanning small samples.
"There are probably more types of CT scanners than cars: sports cars, trucks, whatever you can imagine," Baodong told Science and Technology Daily, in remarks later cited by the South China Morning Post. "This one is the compact car of the CT world.”
CT, or computed tomography, works by combining X-ray images taken from multiple angles into a computer-reconstructed 3D model of an object's interior. The technique dates back to the 1970s, when British engineer Godfrey Hounsfield built the first clinical scanner in London, which was later used to detect a brain tumor.
Squeezing that same imaging principle – the X-ray source, a rotating stage, and a detector – into a space measuring just 140 x 132 x 220 mm (5.5 x 5.2 x 8.6 in) without losing image quality has been the real engineering challenge.
The Xtomo-Cube isn't meant to replace a hospital or an industrial scanner. Its scanning field is only 16 mm (0.63 in) in diameter, meaning it can only image small objects, not human bodies. What makes it useful is precisely what makes it small: an X-ray source running at just 50 kVp (kilovolt peak, a measure of X-ray energy), far lower than a medical scanner uses. That lower energy also means the machine needs much less radiation shielding around it.
The detector, essentially the device's retina, uses pixels just 18.5 micrometers (0.0007 in) across; the smaller the pixel, the finer the image grid. The scanner's spatial resolution, meaning the smallest detail it can distinguish in a reconstructed image, is 80 micrometers (0.003 in), roughly the thickness of a human hair.
At around 200 watts of power draw, the Xtomo-Cube can run off a portable phone-charging battery pack, which the company says makes it practical for fieldwork. Ruiying also pitches it for university teaching, since the lower voltage reduces radiation risk, and, unlike many closed commercial systems, its scanning parameters are adjustable and give users access to raw data for experimenting with image-reconstruction algorithms.
Ruiying hasn't disclosed pricing or a launch date for the Xtomo-Cube. But if it delivers on its promise, this pocket-sized scanner could spare archaeologists and geologists the headache of packaging fragile finds, shipping them to a lab, and waiting weeks for results. Instead, they could peer inside ancient seeds, small amulets, or sediment cores on-site within minutes, deciding in real time whether a dig is worth continuing.