Separation of two radionuclides in simultaneous 123I/99mTc SPECT with artificial neural networks

This study was carried out to reconstruct quantitative images in simultaneous ¹²³I/^99mTc SPECT. In the ¹²³I/^99mTc SPECT study the image reconstructed with the counts of primary photons emitted from the radionuclide with low photopeak energy (^99mTc) is distorted by Compton scattered photons originating in the radionuclide with high photopeak energy (¹²³I). To correct the scattered photons included in the low energy photopeak window in the simultaneous data acquisition, we proposed a method with a neural network at the 1999 IEE Medical Imaging Conference. In this paper we investigated the performance of our method with Monte Carlo simulations and phantom experiments with a brain phantom and a myocardial phantom. The results showed that our method could separate ^99mTc and ¹²³I with an error of about 4% The results promised to enable us to make clinical trials with dual radionuclides.