Estimation and analysis ofSvalues for¹³¹I using paediatric mesh type reference computational phantoms.

Area of Science:

• Medical Physics
• Radiological Dosimetry
• Computational Biology

Background:

• Accurate internal dosimetry is critical for paediatric radioiodine (131I) therapies and nuclear emergency preparedness.
• Computational phantoms are essential tools for estimating organ absorbed doses, but their specific design can influence results.
• Paediatric phantoms require age- and sex-specific representations for reliable dose calculations.

Purpose of the Study:

• To investigate the impact of paediatric mesh-type computational phantoms on organ S-values from thyroid-emitted 131I.
• To compare S-values derived from mesh phantoms against those from voxel phantoms.
• To provide age- and sex-specific S-value data for the paediatric population.

Main Methods:

• Utilized Geant4 Monte Carlo simulation toolkit.
• Estimated 131I S-values for 30 radiosensitive target tissues (Target ← Thyroid).
• Employed reference paediatric mesh-type computational phantoms, comparing results with voxel phantoms.

Main Results:

• S-values differed between male and female phantoms of the same age, with ratios typically within 10%.
• S-values decreased with increasing phantom age.
• Mesh phantoms yielded approximately 17% higher S-values on average compared to voxel phantoms, particularly for separately remodelled organs.

Conclusions:

• Paediatric mesh-type computational phantoms significantly influence 131I organ S-values.
• Age and sex represent important factors in paediatric dosimetry.
• The findings enhance organ dose estimation accuracy for paediatric radioiodine exposure scenarios.