Absorbed dose estimates to structures of the brain and head using a high-resolution voxel-based head phantom

Area of Science:

• Medical Physics
• Radiotherapy Research
• Computational Biology

Background:

• Boron Neutron Capture Therapy (BNCT) requires precise dosimetry for effective treatment.
• Accurate modeling of human anatomy is crucial for calculating radiation dose distribution.
• Existing head phantoms may lack the resolution needed for detailed structure dosimetry in BNCT.

Purpose of the Study:

• To demonstrate the viability of a high-resolution 3-D head phantom in MCNP for BNCT structure dosimetry.
• To develop and utilize a modified Zubal head phantom for calculating absorbed doses in brain structures.
• To assess radiobiologically equivalent (RBE) doses in critical head and brain structures.

Main Methods:

• Developed a modified Zubal head phantom with over 29 critical structures, represented as a 85x109x120 voxel lattice (2.2x2.2x1.4 mm3 voxels).
• Translated the voxelized phantom into MCNP lattice format for radiation transport simulations.
• Performed MCNP absorbed dose calculations for left lateral, right lateral, and bilateral irradiations using a specific neutron source.

Main Results:

• Calculated absorbed doses and radiobiologically equivalent (RBE) doses for numerous brain and head structures.
• Identified the left motor cortex as receiving the limiting RBE dose during left lateral irradiation.
• Determined the insula cortices receive the limiting RBE dose during bilateral irradiation, with parotid glands close to the limit.

Conclusions:

• The high-resolution 3-D head phantom in MCNP is a viable tool for BNCT structure dosimetry.
• The study provides crucial data for optimizing BNCT treatment planning and dose delivery to critical structures.
• This modeling approach enhances the accuracy of RBE dose calculations, improving treatment efficacy and safety.