Advancing Internal Dosimetry in Personalized Nuclear Medicine: Toward Optimized Radiopharmaceutical Use in Clinical...

Area of Science:

• Nuclear Medicine
• Medical Physics
• Computational Modeling

Background:

• Accurate quantification of absorbed radiation doses from radiopharmaceuticals in human organs is crucial for effective nuclear medicine applications.
• Direct in vivo measurement of these absorbed doses is often impractical, necessitating advanced computational methods.
• Monte Carlo (MC) simulations provide a powerful approach for simulating radiation transport and energy deposition within complex biological systems.

Purpose of the Study:

• To compare and validate three MC-based simulation codes: MCNP6, GATE, and GAMOS, for internal dosimetry calculations.
• To evaluate the performance of these codes in quantifying absorbed doses according to the Medical Internal Radiation Dose (MIRD) formalism.
• To demonstrate the adaptability of these MC frameworks for both diagnostic and therapeutic radiopharmaceutical applications.

Main Methods:

• Utilized three MC codes: MCNP6, GATE, and GAMOS, to perform internal dosimetry simulations.
• Employed the Medical Internal Radiation Dose (MIRD) formalism for dose assessment.
• Simulated ^99mTc-MIBI uptake in the myocardium of an anthropomorphic phantom, assessing dose distributions in target organs at different time points.

Main Results:

• All three MC codes demonstrated strong consistency in organ-specific dose distributions.
• The pancreas, gallbladder, and kidneys consistently received the highest absorbed doses across all simulation codes.
• A consistent organ dose ranking (pancreas > gallbladder > kidneys > spleen > heart/liver) was established, corroborating empirical data.

Conclusions:

• The comparative analysis highlights the complementary strengths of MCNP6, GATE, and GAMOS for internal dosimetry.
• GATE is suitable for high-fidelity clinical applications, GAMOS for rapid prototyping, and MCNP6 as a benchmark tool.
• These MC frameworks offer a validated and adaptable toolkit for advancing internal dosimetry in personalized nuclear medicine and radiopharmaceutical therapy development.