Improved reconstructed image quality in a SPECT system with slit-slat collimation by combination of multiplexed and non-multiplexed data

The desirability of multiplexing in SPECT acquisition remains controversial. Allowing multiplexing is a way of optimizing system sensitivity, however multiplexing has been found to deteriorate the image quality due to the ambiguity in the origin of the projections. In this paper we explore the system designed specifically for brain SPECT based on multi slit-slat (MSS) collimator in which the slit spacing is varied to provide a mix of multiplexed (MX) and non-MX data. The degree of multiplexing for individual slits (DM) is fixed and we vary the fractional number of projections that are multiplexed (FMP). The results showed significant increase in Signal to noise ratio (SNR) due to the reduced noise level in the reconstructed images with insignificant effect on the recovery coefficient (RC) and spatial resolution up to high degrees of multiplexing and with less than 30% non-MX projections. We therefore conclude that multiplexing can be used to increase system sensitivity and therefore reduce noise in the image quality provided that mixed MX and non-MX data are acquired.