PET image reconstruction with energy based scatter correction

In positron emission tomography (PET) imaging, photon pairs, emitted back-to-back by the tracer in the body of the patient, are acquired. From these detected photon pairs, a quantitative image of the tracer concentration is reconstructed. Unfortunately, if a photon undergoes a Compton interaction with an electron in the body of the patient, the photon is scattered into a different direction. In this situation, the photon pair provides unreliable information, which creates an undesired contribution to the patient image, hampering accurate quantification of the tracer uptake. Consequently, correction for this scatter contribution is mandatory. The current standard scatter correction approach relies on fast scatter simulation algorithms. Although this method is usually effective, it fails in some challenging situations. For that reason, some groups are developing more sophisticated simulation algorithms. Other groups are developing energy based methods, which use the measured energies of the photons to improve the estimate of the distribution of scattered photon pairs. In this PhD-project we will study recently proposed energy based scatter correction methods, and develop novel and more accurate scatter-correction algorithms for quantitative PET. Since the scattering probabilities depend on the activity distribution and on the shape and size of the patient body, optimal processing of the photon pairs based on their energies may require tuning of the software parameters for each patient. This in turn may require the application of scatter simulation software, in which case we will have to combine both approaches to scatter correction.