Cellular S-value evaluation based on real human cell models using the GATE MC package.

Area of Science:

• Medical Physics
• Radiological Sciences
• Biophysics

Background:

• Accurate dosimetry at the subcellular level is crucial for targeted radionuclide therapy.
• Existing cellular S-values often rely on simplified geometric models (spheres, ellipsoids) that lack biological realism.
• The Committee on Medical Internal Radiation Dose (MIRD) proposed methods for cellular dosimetric parameters, highlighting the importance of S-values.

Purpose of the Study:

• To investigate the impact of realistic cell geometry on S-values compared to simple models.
• To evaluate the accuracy of S-values derived from polygon-surface phantom models of human cells.
• To assess the influence of cell shape on absorbed dose calculations in targeted radionuclide therapy.

Main Methods:

• Monte Carlo (MC) simulations using the GATE software package.
• Development and utilization of two polygon-surface phantom models: B2B Phantom (lung epithelial) and Liver Phantom (hepatocyte).
• Comparison of S-values calculated for realistic cell models versus simple geometric models (spheres, ellipsoids) of similar volumes.

Main Results:

• S-values calculated using realistic cell models significantly differed from those obtained with simple geometric models.
• The use of polygon-surface phantom models provided more precise cell dose information.
• Differences were analyzed across six source-target region combinations with various electron energies and radionuclides.

Conclusions:

• Realistic, individual human cell models are essential for accurate S-value determination in targeted radionuclide therapy.
• Polygon-surface phantom models offer improved accuracy over simplified geometric approaches.
• These findings will enhance the diagnostic applications of radiotherapy and nuclear medicine.