A step towards safer X-rays

X-rays are a common component of diagnostic testing and industrial monitoring, used for everything from monitoring your teeth to scanning your suitcase at the airport. But the high-energy rays also produce ionising radiation, which can be dangerous after prolonged or excessive exposure.

In a study published in ACS Central Science, researchers have taken a step towards safer X-rays by creating a highly sensitive and foldable detector that produces good quality images with smaller dosages of the rays.

“This advancement reduces detection limits and paves the way for safer and more energy-efficient medical imaging and industrial monitoring,” says co-author Professor Omar Mohammed from the King Abdullah University of Science and Technology (KAUST) in Thuwal, Saudi Arabia.

Just like visible light and radio waves, X-rays are a form of electromagnetic radiation. Their high-energy state allows them to pass through most objects, including the soft tissues of our bodies. To produce an X-ray image, or radiograph, the rays either pass through the body and appear as shadowy shapes on the image, or get stuck in denser tissues like bones, leaving behind a brighter, white area.

The amount of radiation a patient is exposed to during a single scan is not dangerous, and one would have to undergo thousands of scans to start to notice compounding effects. However, these repeated exposures to high-energy rays can damage electronic equipment or pose a risk to people like X-ray technicians. So, it would seem that the fewer rays used during a scan, the better. Unfortunately, fewer rays mean a lower-quality radiograph.

By increasing the sensitivity of the detector, however, a low-dose, high-quality X-ray could theoretically be produced. So, Mohammed and colleagues at KAUST engineered a device that facilitates these safer X-ray conditions.

To increase X-ray detector sensitivity, the researchers aimed to minimise the dark current – the residual background noise – generated by the device. To do so, they created detectors using specialised methylammonium lead bromide perovskite crystals, and then connected these crystals in an electrical configuration known as a cascade.

The cascade configuration nearly halved the dark current, improving the X-ray detection limit by five times compared with previous detectors made from the same crystals, but without the cascade. Radiographs made with the new detector revealed fine details, such as a metal needle piercing a raspberry and the interior components of a USB cable. 

“It demonstrates that cascade-engineered devices enhance the capabilities of single crystals in X-ray detection,” reiterates Mohammed, while the team further states that this technology is a promising method for developing foldable, safer, and sensitive commercial X-ray devices, which would serve to minimise radiation exposure during medical procedures and capture subtle details in industrial monitoring.