Alpha dose modeling in diffusing alpha-emitters radiation therapy-Part I: single-seed calculations in one and two...

Area of Science:

• Medical Physics
• Radiation Oncology
• Nuclear Medicine

Background:

• Diffusing alpha-emitters Radiation Therapy (DaRT) utilizes alpha particles for solid tumor treatment.
• DaRT involves interstitial seeds releasing alpha emitters that diffuse within the tumor.
• Accurate alpha dose calculations require advanced modeling of atom transport.

Purpose of the Study:

• To extend the Diffusion-Leakage (DL) model to realistic DaRT seed geometries.
• To develop and validate computational models for DaRT dose calculations.
• To provide guidance for treatment planning in clinical DaRT trials.

Main Methods:

• Derived a closed-form asymptotic solution for a cylindrical alpha source.
• Developed a 1D finite-element numerical scheme for time-dependent dose calculations.
• Investigated a 2D axisymmetric scheme for finite seed geometries.

Main Results:

• Approximating seeds as line sources underestimates alpha dose compared to 2D calculations.
• The 1D time-dependent solution closely matches the 2D solution in the seed midplane.
• The 1D solution maintains accuracy within a few percent up to 2 mm from the seed edge.

Conclusions:

• A full 2D solution is necessary for generating accurate dose lookup tables for DaRT treatment planning.
• The 1D solution is suitable for efficient parametric studies of DaRT seed lattices.
• This work provides essential tools for advancing DaRT clinical applications.