Holst Centre: Improving patient outcomes with next-generation X-Ray technology


The key to optimal patient diagnostics and lower healthcare costs lies in the early detection of diseases. Excellent image quality plays an essential role. TNO at Holst Centre and Siemens Healthineers have demonstrated a new generation of direct-conversion X-ray detectors, based on ultra-sensitive perovskite materials, that significantly boost resolution while simultaneously reducing the X-ray dose.

In 2019, TNO at Holst Centre and Siemens Healthineers started collaborating on this subject in the framework of the EU project ESSENCE, which was followed by the EU-funded PEROXIS project. The partners that collaborate in this project have recently published an article in Nature Electronics. It describes the technologies they have developed for the next generation of highly sensitive X-ray detectors, enabling faster and better diagnostics and treatment.

Albert van Breemen, senior scientist TNO at Holst Centre, explains: "Current X-ray systems mostly use indirect X-ray imaging. This imaging method is highly sensitive, but images are captured at moderate resolution. In mammography systems, current direct X-ray imaging enables a higher resolution to create clear images for diagnosis. But the lower sensitivity requires a higher radiation dose, exposing patients to more radiation than preferred. In order to further boost the technology, we had to find a way to combine high sensitivity with a high resolution."

Perovskites are best known for their use in the fastest-advancing solar-cell technology to date. However, they are also promising in the area of direct-conversion X-ray materials that can be applied over large surfaces at low cost.

Albert: "Since the technology is 'borrowed' from the solar-panel industry, development is faster and less expensive. In fact, current X-ray imagers can simply be refitted with perovskite-based converters, turning indirect imaging into direct imaging."

The integration of direct X-ray converter layers onto a thin-film transistor backplane can be challenging from a manufacturing perspective. Sandro Tedde, senior key expert research scientist at Siemens Healthineers elaborates: "Together with TNO at Holst Centre we have developed a two-step manufacturing process for MAPbI3 X-ray flat-panel detectors. This process is based on the mechanical soft-sintering of a freestanding X-ray-absorbing perovskite wafer that does not require high vacuum and/or high temperatures and its easy integration onto an oxide thin-film transistor backplane. The 500-ppi enabled a resolution of 6 lp mm−1, a sensitivity of 1,060 μCGyair−1 cm−2 and a detection limit of 0.22 nGyair per frame." This means more than double the resolution and potentially a fewfold sensitivity increase compared to current state-of-the-art X-ray detectors.

In the short term, indirect X-ray detectors used in the field of general radiography, fluoroscopy, angiography and neurology will benefit from the improved resolution. Today, these high-resolution detectors are only found in mammography, which uses direct X-ray detection. Sandro adds: "In its turn, mammography will benefit from the improved sensitivity that is so typical for indirect X-ray detectors with a moderate resolution. Improved sensitivities can also lead to lower X-ray doses but with similar or improved image quality."

The development of X-ray detectors with high resolution and high sensitivity can help improve healthcare, as early detection and diagnosis will enable better treatment options, better patient outcomes and lower healthcare costs for medical professionals and patients alike.

Caption: Perovskite X-ray detector (image from Deumel S. et al., Nat. Electron 4, 681–688 (2021))

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