Optimization of yttrium-90 processing on a clinical PET/CT system

Yttrium-90 radioembolization is a common treatment for inoperable hepatocellular carcinoma (HCC), where injected Y-90 microspheres give a targeted radiation dose to malignant tissue in the liver. The biodistribution of microspheres are typically determined by SPECT detection of the Y-90 bremsstrahlung x-rays of the beta decay. Clinical interest in Y-90 PET imaging has arisen recently after high resolution Y-90 PET imaging was demonstrated. However, quantification of microsphere distribution has yet to be established. In this study eleven patients with inoperable HCC underwent SIRT followed by PET. Phantom scans were also performed for quantification, and it was found that the PET scanner was able to properly quantify the distribution to within 0.56% of theoretical values. This information was used to calculate the standardized uptake values (SUV) in patient data. The work presents preliminary results toward achieving a standard protocol for Y-90 PET imaging.