R. Yao et al., EFFECTS OF ENERGY SPACE SMOOTHING AND PROJECTION SPACE NORMALIZATION ON MULTISPECTRAL PET IMAGE QUALITY, IEEE transactions on nuclear science, 43(3), 1996, pp. 1988-1994
Independent processing of multispectral positron emission tomography (
MSPET) data in individual energy frames has the potential to improve s
ystem sensitivity and the accuracy of energy dependent scatter correct
ion. However, statistical fluctuations due to the use of multiple ener
gy windows and low system detection efficiency severely undermine this
potential, These limitations have been overcome without resolution lo
ss by smoothing data in the energy space to suppress statistical fluct
uations and by normalizing detector efficiency in the spatial domain t
o minimize systematic errors. The effectiveness of these corrections w
as evaluated by comparing images acquired in different energy frames w
ith and without energy space smoothing. Smoothing improved the sharpne
ss and contrast and decreased noise of images. The FWHM and FWTM evalu
ated from line source images confirmed an earlier postulate which stat
ed that smoothing in the energy space has no effect on image resolutio
n since such process does not move counts across lines of response (LO
Rs). It was concluded that smoothing in the energy space in conjunctio
n with normalization in the projection space is a prerequisite for sub
sequent energy-dependent data processing such as scatter correction.