Simultaneous Attenuation and Scatter Corrections in Small Animal PET Imaging

The aim of this work is to simultaneously correct for attenuation and scatter in positron emission tomography (PET) by analytically assessing the distribution of the scattered photons using the emission images, the probability of scatter interactions and the detection efficiency. Above the usual lower energy threshold of 300 keV, the attenuated photons are dominantly those which have undergone a Compton scattering. A simple equation is established by considering that each voxel in the image is the measurement of the transmitted photons through the subject, added to the contribution from the other sources by means of their scatter. The solution of this equation allows to correct from scatter and attenuation simultaneously. This new method was applied for data measured with the Sherbrooke small animal PET scanner in line sources, hot spot phantoms, and in rat hearts and tumors.