Assessment of thyroid dose in orthopantomogram imaging with different thyroid shield materials: a Monte Carlo...

Area of Science:

• Radiological Physics
• Biomedical Engineering
• Materials Science

Background:

• Dental radiography, particularly orthopantomogram (OPG) imaging, necessitates radiation protection measures.
• Lead thyroid shields are standard but can cause image artifacts, prompting research into alternatives.
• Minimizing radiation dose to the thyroid is crucial for patient safety in dental procedures.

Purpose of the Study:

• To assess radiation dose reduction to the thyroid using various materials as alternatives to lead thyroid shields in OPG.
• To evaluate the efficacy of bismuth (Bi), bismuth oxide (Bi2O3), and other materials in reducing thyroid dose.
• To compare the performance of full and truncated thyroid shields made from different materials.

Main Methods:

• Utilized the Geant4 simulation toolkit to model an orthopantomogram (OPG) system.
• Simulated radiation dose delivery to a thyroid phantom.
• Investigated lead (Pb), Bi, Bi2O3, stainless steel, and composite shields (polyurethane-Bi2O3, polyurethane-W).

Main Results:

• Full shields of Pb, Bi, Bi2O3, stainless steel, polyurethane-Bi2O3, and polyurethane-W reduced thyroid dose by up to 12.0%, 12.3%, 12.0%, 11.6%, 11.8%, and 12.0%, respectively.
• Truncated shields showed dose reductions ranging from 9.80% to 10.5%.
• Bismuth (Bi) and bismuth oxide (Bi2O3) demonstrated significant thyroid dose reduction, comparable to lead.

Conclusions:

• Bismuth (Bi) and bismuth oxide (Bi2O3) are effective and suitable alternatives to lead thyroid shields in OPG.
• These materials offer comparable radiation protection to lead without introducing significant metal artifacts.
• The findings support the use of Bi and Bi2O3 for enhanced patient safety in dental radiography.