Deep Learning Reconstruction Enables Substantial Radiation Dose Reduction in Ultra-High-Resolution Temporal Bone CT: a Body Donor Study.

PURPOSE: Deep learning reconstruction may enable substantial radiation dose reduction in ultra-high-resolution (UHR) temporal bone CT, but its performance across clinically relevant dose levels remains insufficiently defined. This study evaluated vendor-specific deep learning reconstruction (DLR) compared with hybrid iterative reconstruction (HIR) in UHR volume-mode temporal bone CT and aimed to propose an indication-adapted framework for dose optimization. METHODS: In this single-center body donor study, 20 temporal bones from 10 donors without pathologic findings were scanned at 11 dose levels (CTDIvol, 5.1-30.7 mGy). Images were reconstructed using HIR at standard resolution (0.5 mm, 5122 matrix) and UHR (0.25 mm, 10242 and 20482 matrices), as well as DLR (AiCE Inner Ear) at UHR (0.25 mm, 10242 matrix). Three radiologists independently assessed 10 anatomical structures using a 5-point Likert scale. Signal-to-noise ratio was measured in predefined regions. Exploratory structure-specific generalized estimating equation models were used to estimate the probability of achieving optimal image quality as a function of radiation dose and reconstruction technique. RESULTS: DLR significantly improved visualization of osseous structures compared with HIR (p < 0.001). The exploratory dose-response analysis demonstrated reconstruction-specific trajectories, with DLR achieving higher predicted probabilities of optimal image quality than HIR at lower dose levels. For routine clinical indications, diagnostically adequate image quality was achieved with DLR at a CTDIvol of 13.3 mGy, representing a 48% dose reduction compared with HIR (CTDIvol 25.6 mGy). For high-detail assessment of delicate microanatomical structures, including the stapes and cochlea, DLR achieved excellent visualization at a CTDIvol of 17.4 mGy, corresponding to a 43% dose reduction compared with HIR (CTDIvol 30.7 mGy). CONCLUSION: Vendor-specific DLR enables substantial radiation dose reduction in UHR volume-mode temporal bone CT while maintaining high diagnostic image quality. These findings support an indication-adapted framework for dose optimization, suggesting a routine clinical protocol at CTDIvol 13.3 mGy and a microanatomy-optimized protocol at CTDIvol 17.4 mGy.