Dose Rate Effect on Cell Survival in BNCT.

Area of Science:

• Medical Physics
• Radiation Oncology
• Cell Biology

Background:

• Boron Neutron Capture Therapy (BNCT) relies on precise accelerator output for anti-tumor efficacy and safety.
• Current BNCT protocols mandate rigorous beam quality assessments to limit Relative Biological Effectiveness (RBE) dose errors to within 5%.
• The impact of varying accelerator beam dose rates on biological outcomes in BNCT has not been thoroughly investigated.

Purpose of the Study:

• To investigate the influence of different physical dose rates from accelerator-based BNCT on biological effects.
• To determine if dose rate variations impact cancer cell survival.
• To establish the importance of maintaining a constant beam dose rate in BNCT.

Main Methods:

• Utilized SAS and A172 cancer cells pre-loaded with 10B-boronophenylalanine.
• Irradiated cells with a neutron beam at the Aomori Quantum Science Center, varying accelerator current (100 μA vs. 50 μA).
• Measured thermal neutron flux and delivered physical doses (1.67 Gy and 3.36 Gy) to assess cell survival.

Main Results:

• Thermal neutron flux was reduced by approximately 50% at 50 μA compared to 100 μA.
• Significantly increased cell survival was observed in both SAS and A172 cells following irradiation at the lower dose rate (50 μA) for a 60 mC dose.
• These findings indicate a non-negligible impact of dose rate differences on biological effects.

Conclusions:

• Variations in accelerator BNCT beam dose rates significantly affect biological outcomes, specifically cancer cell survival.
• Consistent and stable beam dose rates are essential for achieving reproducible and effective biological effects in BNCT.
• Dose rate fluctuations should be minimized to ensure reliable BNCT treatment efficacy and safety.