Discrete beta dose kernel matrices for nuclides applied in targeted radionuclide therapy (TRT) calculated with MCNP5

Area of Science:

• Medical Physics
• Nuclear Medicine
• Radiotherapy

Background:

• Targeted radionuclide therapy (TRT) utilizes beta-emitting and electron-emitting nuclides.
• Advances in imaging and modeling enable sophisticated TRT dose calculation systems.
• Deterministic algorithms based on matrix convolution are key for treatment planning.

Purpose of the Study:

• To generate three-dimensional (3D) kernel matrices for various nuclides employed in TRT.
• To establish a comprehensive database for TRT dose calculations.

Main Methods:

• The Monte Carlo code MCNP5 was used to compute discrete dose kernels for beta particles and secondary radiation.
• Calculations were performed for 11 specific nuclides (e.g., 32P, 90Y, 177Lu) in soft tissue.
• Kernels were simulated with voxel sizes of 1 mm³ and 3 mm³.

Main Results:

• Calculated discrete dose kernels showed good agreement with MIRD committee S-value data for several nuclides.
• Deviations were observed in documented analytical kernels near and far from the source.
• The method accurately accounts for secondary particle transport and energy deposition beyond the csda range.

Conclusions:

• The validated method provides a robust database of 3D kernel matrices for TRT beta-radionuclides.
• Discrete kernels overcome limitations of analytical kernels, offering improved accuracy near the source.
• The system allows for resolution-independent dose calculations adaptable to varying voxel dimensions.