On characterizing X-ray detectors for low-dose imaging

Kostiantyn Sakhatskyi^a^,^b, Ying Zhou^c, Gebhard Matt^a^,^b, Jingjing Zhao^d, Jinsong Huang^c^,^e, Sergii Yakunin^a^,^b, Maksym Kovalenko^d

^aLaboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland

^bLaboratory for Thin Films and Photovoltaics, Empa – Swiss Federal Laboratories for Materials Sci-ence and Technology, CH-8600 Dübendorf, Switzerland

^cDepartment of Applied Physical Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

^dSchool of Physical Science and Technology, Chongqing Key Lab of Micro&Nano Structure Optoelectronics, Southwest University, Chongqing, 400715 China.

^eDepartment of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

Proceedings of Perovskite and Organic Semiconductors for Next-Generation Photodetectors and Space Application (NextPDs)

Dubrovnik, Croatia, 2024 June 10th - 12th

Organizers: Michele Sessolo, Beatrice Fraboni and Marisé Garcia-Batlle

Oral, Kostiantyn Sakhatskyi, presentation 004
Publication date: 19th April 2024

In recent years, the X-ray detection research community has been motivated by the emergence of new semiconductor materials, particularly lead-based perovskites [1] and other metal halides. As the focus shifted to synthesizing these novel compounds, the absence of a widely accepted characterization approach for X-ray detectors has led to potentially misleading performance assessments. This Comment proposes guidelines to establish figures-of-merit for low-dose X-ray imagers, enabling accurate comparisons between detectors based on both direct conversion semiconductors and scintillators.

Emerging semiconductors, including lead halide perovskite single crystals, polycrystalline films, nanocrystals, and organic and metal halide scintillators, show promise for developing next-generation low-cost, high-sensitivity X-ray detectors. These materials offer strong stopping power to X-rays and high sensitivity either through high luminescence quantum yield with fast emission as scintillators or large carrier mobility and lifetime product for efficient charge extraction and low thermal noise as semiconductor detectors[2]. However, there is a lack of consensus regarding measurable performance metrics correlating with low-dose X-ray imaging requirements.

To address this issue, we present a set of figures-of-merit based on established Detective Quantum Efficiency (DQE), including Noise Equivalent Dose (NED), Detection Efficiency (DE), half absorption energy, spatial resolution, and a synopsis characteristic: Detective Quantum Efficiency index (DQEi). These guidelines will facilitate the reliable determination of device characteristics for both direct conversion detector materials and indirect scintillators, ultimately supporting the development of novel X-ray medical imaging detectors with improved sensitivity, speed, and spatial resolution.

References:

[1] Yakunin, S., Sytnyk, M., Kriegner, D. et al. Detection of X-ray photons by solution-processed lead halide perovskites. Nature Photon 9, 444–449 (2015).

[2] Sakhatskyi, K., Turedi, B., Matt, G.J. et al. Stable perovskite single-crystal X-ray imaging detectors with single-photon sensitivity. Nat. Photon. 17, 510–517 (2023).

Acknowledgements:

This work was financially supported by the Swiss Innovation Agency (Innosuisse) under grant agreement 46894.1 IP-ENG and by ETH Zürich through the ETH+ Project SynMatLab: Laboratory for Multiscale Materials Synthesis. J. H. acknowledges the financial support from the National Institutes of Health under award 1R01EB033439. The Authors thank Andriy Lomako (Teledyne DALSA, Healthcare X-ray Solutions) as well as Michal Bochenek and Roger Steadman (ams-OSRAM) for insightful discussions.

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