Optimization study on the size of medical radioactive waste liquid sampling container

Abstract

BackgroundWith the development of nuclear medicine, the amount of medical radioactive waste increase rapidly. The radioactivity of nuclides in medical radioactive liquid waste must be monitored to meet the relevant standards before discharge of the radioactive liquid waste. The volume of the waste sample and its distribution around the detector have a direct impact on the detection efficiency.PurposeThis study aims to explore the variation law of the size parameters of the optimal Marlin cup sample box and provide a basis for subsequent monitoring methods.MethodsThe LaBr3(Ce) crystal was applied to the detection of nuclide activity in medical radioactive waste liquid. Geant4 tool was employed to establish a LaBr3(Ce) crystal detection model. The changing rules of the optimal Marin cup sample box size parameters were explored using a Ø25.4 mm×25.4 mm LaBr3(Ce) detector, and 3D printed photosensitive resin samples were used in the laboratory box for verification experiments.ResultsExperimental results show that simply increasing the sample volume cannot improve the detection efficiency, and the change trend of the detection efficiency in the depth direction of the annular part of the sample container tends to be flat with increase of the sample volume. The optimal size ratio of the Marinelli beaker is that the depth of the annular portion (h2) and the radius (r) are approximately two times the length of the detector crystal and the diameter of the hollow cavity, respectively, and the ratio of the radius (r) to the height of the sample container (H) is approximately 0.5. The experimental results of the full energy peak detection efficiency with optimized sample container size are consistent with the simulation results, and the relative deviation is better than 2.5%.ConclusionsThe results of the study provide an important technical reference for detector selection, sampling container design, and processing and traceability methods of medical radioactive liquid waste monitoring devices.

Keywords

• medical radioactive liquid waste
• sampling container size
• optimization
• geant4 simulation
• labr3(ce) detector