Scatter modelling and correction strategies in fully 3-D PET

PET offers the possibility of quantitative measurements of tracer concentration in vivo. However, there are several issues that must be considered in order to fully realise this potential. Whilst, a correction for a number of background and physical phenomena need to be performed, the two most significant effects are the photon attenuation in the patient and the contribution in the images of events arising from photons scattered in the patient and the gantry. The non-homogeneous distribution of attenuation within the thoracic cavity complicates the interpretation of PET images and precludes the application of simple scatter correction methods developed for homogeneous media. The development of more sophisticated techniques for quantification of PET images are still required. Recent progress in 3D PET instrumentation and image reconstructions has created a need for a concise review of the relevance and accuracy of scatter correction strategies. Improved quantification of PET images remains an area of considerable research interest and several research groups are concentrating their efforts towards the development of more accurate scatter modelling and correction algorithms.