서강대학교

초록/요약

Gamma camera is a device used to image gamma radiation emitting radioisotopes in the field of nuclear medical imaging, environmental monitoring, etc. Recently portable gamma camera combined with optical imaging is of great interest to monitor the contamination of radioactive substances at nuclear power plants. In this study, two methods were developed to improve the performance of gamma camera by solving the problem of leakage current and pileup. To overcome the signal loss and noise creation through leakage path in resistor coupled SCD diode was used as splitting element in SCD circuit. Performance evaluation of diode coupled SCD showed 2.1 times higher flood image quality, 9.2% better energy resolution and better uniformity in photopeak energy compared to the conventional resistor coupled SCD. Pileup signal classification and rejection based on the simple neural network was implemented. The trained neural network showed 96% of classification accuracy when four channel peak amplitude, pulse width, and area under the curve were used as input features. Performance evaluation of the pileup classifying network showed 23.4% and 5.1% of improvement on flood image quality and energy resolution in the center region where the most of pileup event was located. The experimental results showed that diode coupled SCD circuit and pileup rejection algorithm were able to improve the performance of gamma camera.