Detection system built from commercial integrated circuits for real-time measurement of radiation dose and quality using the variance method

A small, specialised amplifier using commercial integrated circuits (ICs) was developed to measure radiation dose and quality in real time using a microdosimetric ion chamber and the variance method. The charges from a microdosimetric ion chamber, operated in the current mode, were repeatedly collected for a fixed period of time for 20 cycles of 100 integrations, and processed by this specialised amplifier to produce signal pulse heights between 0 and 10 V. These signals were recorded by a multi-channel analyser coupled to a computer. FORTRAN programs were written to calculate the dose and dose variance. The dose variance produced in the ion chamber is a microdosimetric measure of radiation quality. Benchmark measurements of different brands of ICs were conducted. Results demonstrate that this specialised amplifier is capable of distinguishing differences of radiation quality in various high-dose-rate radiation fields including X rays, gamma rays and mixed neutron-gamma radiation from the research reactor at Texas A&M University Nuclear Science Center.