Medical X-ray imaging improvements contribute to better diagnosis and treatments of many medical conditions. The next breakthrough in radiography will be X-ray spectral imaging, which will make it possible to distinguish much better between the different types of biological tissues of patients’ organs than current imaging techniques. Thus, these highly precise medical imaging based on chemical contrasts will deliver new clinically relevant information to improve the diagnosis, treatments and therapeutic follow-up of patients. This new revolution (X-ray spectroscopy) will only be possible by using direct conversion of X-rays through a photoconductive layer which converts directly X-rays into electrical signals, which is much more favourable in photo-detection efficiency and spatial resolution than the current indirect photo-detection involving a phosphor. Thus, though spectral imaging, these gains in chemical contrast, much more accurate than the finest current analyses, will be combined with significant reduction in the X-ray doses administered to patients.
Measuring the energy of every single X-ray photon impinging the photoconductive layer requires the use of a semiconductor based energy resolved detector. Numerous semiconductors have been developed for X-ray detection. However, so far, there is no identified large area semiconductor capable of measuring the energy of individual X-ray photons in the medical energy range (30-90keV) and at clinical flux. Recently, it has been shown that hybrid organic-inorganic perovskites (particularly CH3NH3PbBr3) are very promising candidates for direct conversion X-ray detectors. Several teams have shown the possibility to use thick freestanding single-crystals perovskite (model material) for discrete X-ray detectors in integration mode, and also in g-ray counting mode. Nevertheless, their capability to work in X-ray counting with a high X-ray flux is still unknown. Moreover, the large area integration will be done preferably by the use of thick solution-processed polycrystalline layers, and the impact of grains boundaries has to be investigated.
Thus, the main objective of PerXI is to develop and assess for spectral medical radiography a new pixelated photodetector based on solution-processed hybrid perovskite, CH3NH3PbBr3, and to measure its spectrometric performances under X-ray irradiation. Single crystalline and thick polycrystalline layers approaches will be compared. The PerXi partners have complementary skills covering all the aspects of this project: nucleation and growth in solution for CNRS, device fabrication and characterisation at CEA, development and manufacturing of X-ray flat panel digital detectors at Trixell. PerXi will increases knowledge in material for radiation detector. Spectral radiography will impact citizens by significantly improving diagnostics and treatments. Industrial applications involve first medical imaging and could be further extended to the whole X-ray detection field.