Metals in PET/CT: Causes and reduction of artifacts in PET images

Metallic objects create artifacts in the PET/CT images. In this work, it is investigated which are the causes of the metal artifacts in the PET images and how these artifacts can be reduced. Based on a simulation study and some phantom measurements, it was found that the main cause for artifacts is an over-and underestimation of the PET attenuation values. Secondly movement also plays an important role in the creation of the PET metal artifacts. To reduce the metal artifacts two methods were proposed: 1) a modified conversion method which ensures the assignment of more correct PET attenuation to the metals, and 2) a simple registration procedure to reduce the motion-related metal artifacts. Both methods are successful in reducing the metal artifacts in the PET images.