Study of CT-based positron range correction in high resolution 3D PET imaging

Positron range limits the spatial resolution of PET images and has a different effect for different isotopes and positron propagationmaterials. Therefore it is important to consider it during image reconstruction, in order to obtain optimal image quality. Positron range distributions for most common isotopes used in PET in different materials were computed using the Monte Carlo simulations with PeneloPET. The range profiles were introduced into the 3D OSEM image reconstruction software FIRST and employed to blur the image either in the forward projection or in the forward and backward projection. The blurring introduced takes into account the different materials in which the positron propagates. Information on these materials may be obtained, for instance, from a segmentation of a CT image. The results of introducing positron blurring in both forward and backward projection operations was compared to using it only during forward projection. Further, the effect of different shapes of positron range profile in the quality of the reconstructed images with positron range correction was studied. For high positron energy isotopes, the reconstructed images show significant improvement in spatial resolution when positron range is taken into account during reconstruction, compared to reconstructions without positron range modeling.This work has been supported by the MEC (FPA2007 62216), the UCM (Grupos UCM, 910059), the CPAN (Consolider Ingenio 2010) CSPD 2007 00042, the RECAVA RETIC network, ARTEMIS S2009/ DPI 1802, the European Regional Development and ENTEPRASE grant, PSE 300000 2009 5 and the Ministerio de Ciencia e Innovación, Spanish Government.Publicad