A team of researchers, led by Professor Yang Yang from State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, China, and co-workers have developed a nontoxic double perovskite scintillator, which exhibits not only a high light yield but also long-term stability under continuous thermal treatment and X-ray irradiation. Scintillators are a key component for detection of X-rays, which convert X-ray photons to visible photons so they are then detected by a photodiode array.
Given the high light output and fast light decay of this new scintillator, static X-ray imaging was attained under an extremely low dose of ~1 μGyair, and dynamic X-ray imaging of finger bending without a ghosting effect was demonstrated under a low dose rate of 47.2 μGyair s-1. These results reveal the huge potential in exploring scintillators beyond lead halide perovskites, not only for avoiding toxic elements but also for achieving higher performance.
Scintillators are capable of converting X-ray photons into visible photons. The plausible mechanism of X-ray scintillation can be described as follows: The radiation energy is first absorbed by the heavy atoms of the scintillators mainly through the photoelectric effect and inelastic Compton scattering, ejecting massive hot electrons; then, these electrons thermalize on an ultrafast timescale and are captured by luminescent centres. These scientists summarize the design principles of scintillator:
"We design the scintillator according to the following three principles:(1) Introduce heavy atom (Bi3+) to improve X-ray absorption efficiency; (2) Weaken self-absorption and improve photoluminescence quantum yield to optimize light out; (3) Reduce afterglow and shorten light decay time to increase the signal-to-noise ratio (SNR) of X-ray imaging."
"The realization of high-resolution X-ray image under an extreme low X-ray dose demonstrate that the X-ray dose requirement for medical X-ray imaging can be significantly reduced in the future." They added.
"The presented scintillators can be used in X-ray computed tomography (CT) and dynamic X-ray imaging, which is important to understand many biological processes and is also useful for online monitoring of industrial process", The scientists forecast.