Optimization parameters for BDE in BNCT using near threshold 7Li(p,n)7Be direct neutrons

Area of Science:

• Nuclear Medicine
• Radiation Oncology
• Materials Science

Background:

• Boron Neutron Capture Therapy (BNCT) relies on the (10)B(n,alpha)(7)Li reaction for targeted cell killing.
• Enhancing the dose contribution of this reaction is crucial for improving BNCT efficacy, especially with direct neutron sources.
• Boron-dose enhancers (BDEs) are materials designed to optimize dose distribution in BNCT.

Purpose of the Study:

• To determine optimal criteria for Boron-Dose Enhancers (BDEs) in BNCT using near-threshold (7)Li(p,n)(7)Be direct neutrons.
• To evaluate the impact of various candidate BDE materials on dose distribution and treatable protocol depth (TPD).
• To identify suitable BDE materials for shallow and deep-seated tumor treatments.

Main Methods:

• Candidate BDE materials including polymers ((C(2)H(4))(n), (C(2)H(3)F)(n), etc.), beryllium metal, graphite, D(2)O, and (7)LiF were investigated.
• The Treatable Protocol Depth (TPD) was used as the primary index to assess dose distribution.
• The dependence of TPD on BDE thickness was analyzed for each material.

Main Results:

• Maximum TPD (TPD(max)) showed minimal dependence on BDE material type.
• TPD's dependence on BDE thickness was significantly influenced by the presence of hydrogen in the material.
• Hydrogen-containing BDEs required thinner optimal thicknesses (BDE(TPD(max))) compared to non-hydrogenous materials.

Conclusions:

• TPD(max), TPD dependence on BDE thickness, and BDE(TPD(max)) are effective BDE optimization parameters.
• Polyethylene ((C(2)H(4))(n)) is recommended as a BDE for shallow tumors due to its favorable characteristics.
• Beryllium metal is suggested as a more appropriate BDE for deep-seated tumors.