A Multicenter Study on Observed Discrepancies Between Vendor-Stated and PET-Measured 90Y Activities for Both Glass and Resin Microsphere Devices

Dosimetry-guided treatment planning in selective internal radiation ther-apy relies on accurate and reproducible measurement of administered activity. This 4-center, 5-PET-device study compared the manufacturer -declared 90Y activity in vials with quantitative 90Y PET/CT assessment of the same vials. We compared 90Y PET-measured activity (APET) for 56 90Y-labeled glass and 18 90Y-labeled resin microsphere vials with the calibrated activity specified by the manufacturer (AM). Additionally, the same analysis was performed for 4 90Y-chloride vials. The mean APET/ AM ratio was 0.79 & PLUSMN; 0.04 (range, 0.71-0.89) for glass microspheres and 1.15 & PLUSMN; 0.06 (range, 1.05-1.25) for resin microspheres. The mean APET/ AM ratio for 90Y-chloride vials was 1.00 & PLUSMN; 0.04 (range, 0.96-1.06). Thus, we found an average difference of 46% between glass and resin micro -sphere activity calibrations, whereas close agreement was found for chloride solutions. We expect that the reported discrepancies will pro-mote further investigations to establish reliable and accurate patient and dose-effect assessments.

Automated summary

Dosimetry-guided treatment planning in selective internal radiation therapy requires accurate measurement of administered activity. This study compared the manufacturer-declared 90Y activity in vials with quantitative assessment using PET/CT. Significant differences in activity calibration were found between glass and resin microspheres, while chloride solutions showed close agreement. These findings highlight the need for further investigations to ensure reliable and accurate patient and dose-effect assessments.