3D tibial HU reconstruction from biplanar X-rays utilizing a hybrid PCA-CNN framework
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Published version
Author(s)
Huppe, Maxime
Myant, Connor
Type
Journal Article
Abstract
High-resolution Computed Tomography (CT) is the gold standard medical imaging technique for bone assessment. However, its clinical use is limited by high radiation dose (8.8 mSv; biplanar X-rays 1.4 mSv), cost, and reduced accessibility. These barriers are particularly significant for patients requiring frequent imaging. This study introduces a novel hybrid framework combining statistical intensity modeling with Deep Learning to reconstruct 3D tibial CT volumes including internal density distributions from biplanar radiographs. The method employs principal component analysis (PCA) to capture intensity variations in a compact latent space and trains a convolutional neural network (CNN) to regress PCA coefficients directly from radiographs. The framework was developed and validated using 60 subjects from the publicly available Korea Institute of Science and Technology Information (KISTI) database. Compared to ground truth CT, it achieved a mean absolute error of 127.17 ± 12.08 Hounsfield Units (HU), a structural similarity index of 0.8558 ± 0.0215, and a peak signal-to-noise ratio of 21.40 ± 0.78 dB. The method has the potential to achieve substantial radiation dose reduction compared to conventional CT while preserving sufficient anatomical detail for potential clinical tasks such as patient-specific implant planning and bone quality triage. However, the actual dose reduction depends on clinical imaging protocols and requires validation through protocol-matched dosimetry on actual radiographs. Moreover, it produces interpretable outputs that reflect anatomical intensity variations (e.g., cortical vs. trabecular regions), demonstrating feasibility for hybrid statistical-Deep Learning bone reconstruction. The proposed pipeline establishes a foundation for reduced-dose 3D bone imaging and offers a pathway toward clinical translation pending validation on real-world radiographic data.
Date Issued
2026-02-01
Date Acceptance
2026-01-07
Citation
Computers in Biology and Medicine, 2026, 202
ISSN
0010-4825
Publisher
Elsevier
Journal / Book Title
Computers in Biology and Medicine
Volume
202
Copyright Statement
Copyright This paper is embargoed until publication. Once published the Version of Record (VoR) will be available on immediate open access.
License URL
Identifier
10.1016/j.compbiomed.2025.111434
Publication Status
Published
Article Number
111434