Development of a capacitance-integrating radioactivity meter

Abstract

BackgroundRapid and accurate measurements of radionuclide activities in the field play an important role in radiological medical diagnosis.PurposeThis study aims to develop a capacitance-integrated activity meter.MethodsA circuit structure of the capacitive-integral type was adopted to design a low-noise preamplifier circuit. The designed structure was matched with high-precision signal acquisition and processing circuit to successfully develop a weak current measurement circuit, achieving weak current measurements ranging from 20 fA to 10 μA. The Geant4 simulation software was employed to simulate the ionization chamber used in the current design to obtain correction factors for different nuclides. Finally, three different radiation sources were used for performance testing of this self-developed radioactivity meter, and compared with a commercial RM-905A radioactivity meter.ResultsThe test results show that the repeatability of the proposed radioactivity meter is consistent with the performance of the commercial RM-905A radioactivity meter, with a background lower than 0.065 MBq, a repeatability of 0.84% at most, and an instability of 1.94%.ConclusionsThe capacitive integral radioactivity meter developed in this study can be used as an alternative instrument for commercial radioactive activity meter RM-905A.

Keywords

• radioactivity meter
• 4πγ ionization chamber
• capacitance integral circuit
• field programmable gate array