Real-Time Monitoring In Boron Neutron Capture Therapy Using LaBr₃ Scintillation Detector
Abstract
Purpose
To investigate the feasibility of real-time monitoring of boron neutron capture therapy (BNCT) through prompt gamma detection using a LaBr₃ scintillation detector, with the goal of enabling quantitative assessment of boron distribution during treatment.
Methods
A 120 mL cylindrical phantom was filled with boric acid solutions with boron concentrations ranging from 0 to 1000 ppm. Two neutron sources were employed: a ²³⁹Pu–Be source and a Tandetron accelerator utilizing the ⁷Li(p,n) reaction. Prompt gamma rays generated from neutron interactions within the boron-containing phantom were measured using a LaBr₃ scintillation detector. The phantom was positioned immediately downstream of the neutron source, while the detector was placed perpendicular to the neutron beam direction to minimize neutron-induced damage to the LaBr₃ crystal. For experiments using the ²³⁹Pu–Be source, which provides neutrons with an average energy of approximately 4 MeV and a yield of 4 × 10⁷ n/s, each boron sample was irradiated for durations of 1, 3, 10, and 20 minutes. Prompt gamma spectra were recorded for each irradiation. Similar experimental procedures were followed for measurements performed using the Tandetron neutron source. The detection limit of the LaBr₃ detector was evaluated by constructing a calibration curve of the 478 keV prompt gamma count rate as a function of boron concentration.
Results
A linear relationship between the 478 keV prompt gamma count rate and boron concentration was observed over the investigated range. Using the ²³⁹Pu–Be neutron source, the LaBr₃ scintillation detector achieved a minimum detectable boron concentration of 28.8 ppm.
Conclusion
This study demonstrates that a LaBr₃ scintillation detector is capable of real-time monitoring in boron neutron capture therapy through prompt gamma detection. Future work will investigate detector performance with collimation and extend the methodology to cell irradiation experiments using boric acid and a Tandetron-based neutron source.