TY - JOUR T1 - Evaluation of Y90 PET/CT for imaging and quantifying Y90 dose in vivo JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1986 LP - 1986 VL - 52 IS - supplement 1 AU - S. Cheenu Kappadath AU - Osama Mawlawi Y1 - 2011/05/01 UR - http://jnm.snmjournals.org/content/52/supplement_1/1986.abstract N2 - 1986 Objectives Since Y90 emits β+ at low yields (branching ratio 32-34 ppm), PET could potentially be used to assess absorbed dose and spatial distribution of Y90 microspheres post-therapy. Our objectives are to establish clinical scan duration, measure Y90 spatial resolution, and evaluate accuracy of quantified Y90 PET images. Methods Five 60mL syringes containing 15mL 90YCl of known activities (corresponding to absorbed doses of 27, 43, 88, 146, 260 Gy) were scanned for 30min in list mode on a clinical PET/CT scanner with syringes (a) suspended in air, and (b) inserted into a block of solid water. In addition, a cylindrical (ID=22cm) water-filled phantom containing 2 cylinders (287mL) of known Y90 activity (absorbed doses 41 & 64 Gy) was scanned for 30min in list mode on the PET/CT scanner. A 1mm capillary tube containing Y90 was placed inside the phantom to measure the Y90 spatial resolution with scatter. In all three experiments, PET emission data was rebinned to 30, 20, 15, 10 min/bed and reconstructed using clinical protocol with F18 as radionuclide but decay-correction off. Reconstructed image quality at different scan durations was assessed to establish suitable scan duration. The mean PET signal of a central ROI in the cylinders and syringes were computed and corrected using 32 ppm β+ branching ratio to quantify PET-based Y90 activity [Bq/mL] and dose [Gy]. The accuracy of quantified Y90 PET images was evaluated for syringes in-air and cylinders in-scatter. Results PET acquisition times of ~15 min/bed was determined to be suitable for imaging patients with tumor doses >90 Gy. The Y90 PET spatial resolution in scatter was measured to be ~9.7 mm. The quantified Y90 PET images had an average accuracy (range) of 7% (2-13%) for the cylinders in-scatter, and 17% (3-25%) for the syringes in-air. The in-scatter and in-air PET images predicted β+ branching ratios of 33 and 36.4 ppm, respectively. Conclusions Y90 spatial distribution for tumor doses >90 Gy can be well assessed using ~15 min/bed PET scans. Absorbed doses from implanted Y90 microspheres can be estimated to an accuracy of ~10% using Y90 PET/CT images ER -