This preliminary study investigates the potential of perovskite quantum dots (QDs) as scintillators for clinical X-ray dosimetry. Perovskite QDs, known for their high scintillation efficiency and cost-effectiveness, have shown promise in various fields such as solar cells and light-emitting diodes. Our research aims to explore their suitability for X-ray imaging dosimetry.

We synthesized halide perovskite QDs (CsPbX3, X = Br, I, or Cl) using low-polarity solvents (Toluene, Octane, and Cyclohexane) to create a liquid scintillator. The scintillation signal was enhanced by adding an organic scintillator, 2,5 diphenyloxazol (PPO). A custom-designed Teflon applicator focused the scintillation light from QDs to an optical fiber within a 2 ml glass vial. Scintillation signals were measured using a compact CCD spectrometer (CCS200TM, Thorlabs) with a wavelength range of 200-1,000 nm.

The QD scintillator was exposed to 4-15 MV photon beams and 6-9 MeV electron beams from a LINAC (TruebeamTM, Varian). Absorbed dose was determined using a Farmer-type ion chamber under consistent conditions. We examined scintillation responses based on dose rate, energy type, and beam quality. To assess the feasibility of perovskite QDs as clinical radiation dosimeters, we evaluated their linearity, saturation effect, reproducibility, and dose tolerance.

Our initial findings show that CsPbBr3 in toluene exhibited the highest scintillation efficiency for both kV and MV X-ray beams. PPO doping amplified the scintillation signals, a mechanism we explored based on previous research. [1] The scintillation response increased linearly between 100 and 1000 cGy for all photon and electron energies tested. Importantly, the samples showed reproducible scintillation responses without significant changes in emission peaks or signal intensity over ten consecutive measurements.

In our preliminary dose tolerance tests, we irradiated the perovskite QDs and PPO-doped scintillator sample up to 1040 Gy. We observed only a 1% change in scintillation response up to 50 Gy, with a 50% reduction occurring after 1040 Gy irradiation. We also examined physical changes due to radiation damage using transmission electron microscopy.

This investigation suggests that perovskite QD-doped organic liquid scintillators show promise as convenient and accurate clinical X-ray dosimeters. Their advantages include high scintillation efficiency, low manufacturing cost, and real-time dose measurement without pre- or post-processing. While further research about dose tolerance and storability are needed, these preliminary results indicate that perovskite QDs are promising candidates for clinical dosimetry applications.