Abstract
1079
Learning Objectives Selective Internal Radiation Therapy, utilizing microspheres impregnated with beta-emitters to deliver embolic radiation has tremendous potential in treating late-stage inoperable disease. Post therapy imaging is useful for determining adequate delivery of energy to target tissues, and verify non-target tissues is spared. While gamma cameras can be used to image bremsstrahlung emissions from beta emitters, they are often of poor quality. Newer cameras and techniques have enabled the use of PET Y-90 imaging, however, these techniques are of limited utility on older generation cameras. This poster will give an overview of the concepts governing both PET and gamma/x-ray imaging techniques.
While Y-90 is an excellent therapeutic radionuclide, as a nearly purely beta emitter it has not enjoyed the same popularity in imaging as other agents. As it emits no gammas in the useful range of most detectors, practitioners have relied on bremsstrahlung, or braking radiation to localize Y-90. Bremstrahlung, which results from complex interactions between beta particles and tissue, has an equally complex imaging spectrum and is susceptible to considerable artifact. It has been known that Y-90 also produces rare positrons, which can be imaged with PET. Newer systems, particularly those employing Time-of-flight [TOF] imaging have shown promise in creating high-resolution images of Y-90. This poster will look at the techniques bremsstrahlung imaging, particularly with regards to SPECT, and compare to Y-90PET. We will demonstrate some of the approaches taken at our institution to implement non-TOF PET, and discuss the costs and benefits of adopting this method of post-therapy imaging. Discussion will be focused on optimizing parameters for obtaining PET images on earlier generation cameras, such as through the use of 3D mode, providing heuristics to determine optimal imaging, by chronicling our experiences implementing both SPECT and PET techniques