Purpose: To optimise, design, and benchmark low cost, high spatial resolution, direct conversion Perovskite crystal x-ray flat panel imagers for a next generation of breast-, MV-, and kV-cone beam CT (CBCT) detectors.
Methods: The design of Perovskite crystal, direct conversion, flat panel imagers have been optimised using Monte Carlo (MC) simulation methods. TOPAS MC calculations of energy deposition efficiency (EDE) in semiconductor MAPbBr3 Perovskite crystals were benchmarked against four common detector materials for twelve detector crystal thicknesses between 40 μm to 15 mm and ten beam energy spectra ranging from 20 kVp to 6 MV. Based on EDE simulations, Koning’s dedicated breast CT, and Varian’s Truebeam MV- and kV-CBCT systems were designated as suitable applications for Perovskite detectors. System specific Fastcat hybrid-MC CBCT image simulation was subsequently used to optimise the Perovskite detector design and benchmark image quality according to contrast to noise ratio (CNR) and detective quantum efficiency (DQE) against each system's current detector options.
Results: Device-specific optimal Perovskite crystal thicknesses were calculated to be 0.8, 2.1, and 3.8 mm for Koning’s breast CT and Varian’s kV- and MV-CBCT systems, respectively. The optimal Perovskite detector resulted in increased breast micro-calcification contrast by a factor of 1.87 compared to the default CsI detector. The optimal kV-CBCT Perovskite detector increased CNR in brain and skull by factors of 1.19 and 1.10, respectively, while for MV-CBCT the Perovskite detector increased CNR in lung and C4-vertebra by factors of 9.07 and 11.2, respectively.
Conclusion: Replacing existing detectors with novel low-cost Perovskite detectors is demonstrated to improve CNR by factors between 1.1-11.2 with a marked increase in spatial resolution. Design optimization will be followed by manufacturing and experimental characterization ahead of commercial utilisation of Perovskite in medical imaging applications.
Funding Support, Disclosures, and Conflict of Interest: This work was partially funded by the National Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant, Canada Research Chair program.
IM/TH- Cone Beam CT: Development (New Technology and Techniques)