Investigation of the Accuracy of Scatter Correction in 3D body scanning on the HR+PET tomography

Abstract

The accuracy of scatter correction in 3D body scanning on the HR + PET tomography has been investigated using both a uniform (Utah) phantom with various compartments and inserts, and a body shaped phantom with heart and liver inserts. With both phantoms, scans were made with one compartment outside and others inside the field-of-view to see how radioactivity outside the field-of-view could affect the measurements of image counts. In most cases where the scattered correction had worked efficiently, the ratio of the mean activity of the region of interest to the region of interest of the surrounding ‘background’ mean activity is less than 5%. The investigations further revealed that the accuracy of scatter correction depend not only on the shape, size of the source body, but also on the radioactivity distribution inside the field-of-view of the PET scanner. The presence of an additional radioactive region inside the field-of-view is, however, a source of a potentially noisy image data, and since noise can cause artefacts in scatter correction, it is therefore necessary to ensure that adequate filtering and attenuation corrections are applied to the data prior to scatter correction. The provision of side shielding could help to improve the detection efficiency of the PET scanner, and also prevent unnecessary exposure to clinicians.