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<p>This study investigates PMMA-based composites enhanced with high-Z metal oxides (SnO₂, La₂O₃, Sm₂O₃, Er₂O₃, WO₃, and PbO) for dental diagnostic X-ray shielding. The oxides were selected for their K-edge energies lying within the 20–90&#xa0;keV range relevant to dental radiology. PbO was included only as a benchmark material, while the other oxides were evaluated as safer, eco-friendly alternatives. Geant4 Monte Carlo simulations, validated against NIST XCOM with &lt; 1% deviation, were employed to calculate key shielding parameters including linear attenuation coefficient (LAC), mean free path (MFP), half-value layer (HVL), tenth-value layer (TVL), effective atomic number (Z<sub>ₑff</sub>), and effective electron density (N<sub>ₑff</sub>). The results demonstrate that each oxide significantly improves PMMA’s attenuation capability, particularly at photon energies just above its K-edge. In the investigated energy range, sharp enhancements in LAC, Z<sub>eff</sub>, and N<sub>eff</sub>, along with reductions in MFP, HVL, and TVL, were observed. Specifically, the maximum LAC values reached 15.309&#xa0;cm⁻¹ for PMMA–Sn at 30&#xa0;keV, 10.356&#xa0;cm⁻¹ for PMMA–La at 40&#xa0;keV, 7.353&#xa0;cm⁻¹ for PMMA–Sm at 50&#xa0;keV, 5.761&#xa0;cm⁻¹ for PMMA–Er at 60&#xa0;keV, 4.204&#xa0;cm⁻¹ for PMMA–W at 70&#xa0;keV, and 3.300&#xa0;cm⁻¹ for PMMA–Pb at 90&#xa0;keV, corresponding closely to the K-edge energies of the respective elements. Notably, all composites outperformed PbO in attenuation efficiency within their respective K-edge regions. These findings highlight the potential of strategically exploiting K-edge absorption to design lightweight, non-toxic PMMA-based shielding materials optimized for specific dental imaging modalities.</p>

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K-edge optimization of PMMA-based metal oxide shields for dental X-ray protection using Geant4 Monte Carlo simulations

  • 期刊论文

  • 发表日期：

    2026年6月16日

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  • Mahmoud T. Alabsy,
  • Mai. I. El‑kaliuoby,
  • Ahmed M. El-Khatib,
  • Alaa M. Khalil

摘要

This study investigates PMMA-based composites enhanced with high-Z metal oxides (SnO₂, La₂O₃, Sm₂O₃, Er₂O₃, WO₃, and PbO) for dental diagnostic X-ray shielding. The oxides were selected for their K-edge energies lying within the 20–90 keV range relevant to dental radiology. PbO was included only as a benchmark material, while the other oxides were evaluated as safer, eco-friendly alternatives. Geant4 Monte Carlo simulations, validated against NIST XCOM with < 1% deviation, were employed to calculate key shielding parameters including linear attenuation coefficient (LAC), mean free path (MFP), half-value layer (HVL), tenth-value layer (TVL), effective atomic number (Zₑff), and effective electron density (Nₑff). The results demonstrate that each oxide significantly improves PMMA’s attenuation capability, particularly at photon energies just above its K-edge. In the investigated energy range, sharp enhancements in LAC, Zeff, and Neff, along with reductions in MFP, HVL, and TVL, were observed. Specifically, the maximum LAC values reached 15.309 cm⁻¹ for PMMA–Sn at 30 keV, 10.356 cm⁻¹ for PMMA–La at 40 keV, 7.353 cm⁻¹ for PMMA–Sm at 50 keV, 5.761 cm⁻¹ for PMMA–Er at 60 keV, 4.204 cm⁻¹ for PMMA–W at 70 keV, and 3.300 cm⁻¹ for PMMA–Pb at 90 keV, corresponding closely to the K-edge energies of the respective elements. Notably, all composites outperformed PbO in attenuation efficiency within their respective K-edge regions. These findings highlight the potential of strategically exploiting K-edge absorption to design lightweight, non-toxic PMMA-based shielding materials optimized for specific dental imaging modalities.