Response control of RPLGD for gamma-ray dose measurement using lead filters for BNCT

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Nuclear Engineering

Background:

• Boron Neutron Capture Therapy (BNCT) utilizes ¹⁰B neutron capture reactions for cell-selective radiotherapy.
• Accelerator-Based Neutron Sources (ABNS) are emerging for next-generation BNCT, but produce secondary gamma-rays.
• Existing dosimeters struggle to differentiate gamma-rays from neutrons in mixed fields.

Purpose of the Study:

• To develop a method for isolating gamma-ray measurements within mixed neutron-gamma radiation fields.
• To improve the sensitivity of gamma-ray detection, particularly for low-energy gamma rays (∼100 keV).
• To enable accurate dosimetry for BNCT applications using ABNS.

Main Methods:

• Utilized fluorescent glass dosimeters (RPLGD) for radiation detection.
• Proposed and refined a lead filter method, including a specially shaped filter, to distinguish gamma-ray signals.
• Conducted theoretical calculations and experimental validation with gamma-ray sources and in a nuclear fuel storage room.

Main Results:

• The specially shaped lead filter method demonstrated improved sensitivity to low-energy gamma rays.
• Theoretical calculations indicated the potential to estimate air dose rates up to 10 MeV for known gamma-ray spectra.
• Experimental results confirmed the validity of the lead filter method in mixed radiation environments.

Conclusions:

• The developed lead filter method effectively separates gamma-ray measurements in mixed neutron-gamma fields.
• This technique enhances the accuracy of dosimetry for BNCT, especially with ABNS.
• The method shows promise for reliable gamma-ray assessment in complex radiation settings.