The measurement of thermal neutron flux depression for determining theconcentration of boron in blood

Abstract

Boron neutron capture therapy (BNCT) is a form of targeted radiotherapy thatrelies on the uptake of the capture element boron by the volume to be treated.The treatment procedure requires the measurement of boron in the patient'sblood. The investigation of a simple and inexpensive method for determiningthe concentration of the capture element 10B in blood is describedhere. This method, neutron flux depression measurement, involves thedetermination of the flux depression of thermal neutrons as they pass througha boron-containing sample.It is shown via Monte Carlo calculations and experimental verification that,for a maximum count rate of 1×104 counts/s measured by thedetector, a 10 ppm 10B sample of volume 20 ml can be measured with astatistical precision of 10% in 32±2 min. For a source activity ofless than 1.11×1011 Bq and a maximum count rate of less than1×104 counts/s, a 10 ppm 10B sample of volume 20 mlcan be measured with a statistical precision of 10% in 58±3 min. Ithas also been shown that this technique can be applied to the measurement ofthe concentration of any element with a high thermal neutron crosssection such as 157Gd.