Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine · 2026
High-fidelity Monte Carlo dosimetry of radiosensitive organs in head and neck CT: A virtual TLD study with comprehensive statistical uncertainty analysis.
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Khoshhal Amir Reza, Torshabi Ahmad Esmaili, Zehtabian Mehdi
Аннотация
PURPOSE: To quantify absorbed doses to six critical head and neck organs (occipital lobe, temporal lobe, hypothalamus, thalamus, parotid gland, and both eyes) during head CT using high-fidelity Monte Carlo simulation as an ethical alternative to in vivo dosimetry.
METHODS: A voxelized phantom was generated from DICOM images of the RANDO phantom. A realistic X-ray tube (135 kVp) was modeled in GEANT4 (v11.1.3) to simulate clinical head CT protocols. Seventy-four virtual GR-200 thermoluminescent dosimeters (TLDs) were placed at predefined organ coordinates, and 2 × 108 primary photons were tracked. Descriptive statistics (mean, SD, SEM, 95% CI, CV%) and non-parametric tests (Kruskal-Wallis followed by Mann-Whitney U with Bonferroni correction) were applied to the raw dose distributions.
RESULTS: The parotid gland received the highest mean dose (25.83 mGy) and the right eye the lowest (19.10 mGy). The temporal lobe exhibited the smallest variability (CV = 0.39%), while the right eye showed the largest (CV = 11.52%). The Kruskal-Wallis test revealed highly significant differences among organs (H = 62.34, p = 1.5 × 10-11). Pairwise comparisons indicated that the parotid gland dose was significantly higher than both eyes (p ≈ 3.2 × 10-4), whereas no significant difference existed between the two eyes (p = 0.86) or between occipital and temporal lobes (p = 0.43). Dose ratios relative to the thalamus ranged from 0.824 (right eye) to 1.114 (parotid gland).
CONCLUSION: The statistically robust organ-dose estimates validate the GEANT4-based model and align with previous experimental data. Monte Carlo simulation with strategically placed virtual TLDs offers a powerful, ethical tool for precise dose assessment, providing a valuable reference for protocol optimization and radiation protection in head and neck CT.
METHODS: A voxelized phantom was generated from DICOM images of the RANDO phantom. A realistic X-ray tube (135 kVp) was modeled in GEANT4 (v11.1.3) to simulate clinical head CT protocols. Seventy-four virtual GR-200 thermoluminescent dosimeters (TLDs) were placed at predefined organ coordinates, and 2 × 108 primary photons were tracked. Descriptive statistics (mean, SD, SEM, 95% CI, CV%) and non-parametric tests (Kruskal-Wallis followed by Mann-Whitney U with Bonferroni correction) were applied to the raw dose distributions.
RESULTS: The parotid gland received the highest mean dose (25.83 mGy) and the right eye the lowest (19.10 mGy). The temporal lobe exhibited the smallest variability (CV = 0.39%), while the right eye showed the largest (CV = 11.52%). The Kruskal-Wallis test revealed highly significant differences among organs (H = 62.34, p = 1.5 × 10-11). Pairwise comparisons indicated that the parotid gland dose was significantly higher than both eyes (p ≈ 3.2 × 10-4), whereas no significant difference existed between the two eyes (p = 0.86) or between occipital and temporal lobes (p = 0.43). Dose ratios relative to the thalamus ranged from 0.824 (right eye) to 1.114 (parotid gland).
CONCLUSION: The statistically robust organ-dose estimates validate the GEANT4-based model and align with previous experimental data. Monte Carlo simulation with strategically placed virtual TLDs offers a powerful, ethical tool for precise dose assessment, providing a valuable reference for protocol optimization and radiation protection in head and neck CT.