Table 1.

Physical Properties of Commercially Available Y90 Microspheres.

	Y90 Glass Microspheres (TheraSphere)	Y90 Resin Microspheres (SIR-Spheres)
Microsphere mean diameter	25 ± 10 μm	35 ± 10 μm
Matrix	Insoluble glass	Insoluble resin
Density	3.6 g/dL	1.6 g/dL
Mean radioactivity per microsphere	2500 Bq	50 Bq
Number of microspheres per 3 GBq	1.2 million	60 million
Activities available	3, 5, 7, 10, 15, 20 Bq	3 Bq
Spheres per vial	1.2-8 million	40-80 million
Embolic effect	Mild	Moderate