Table 1.

Characteristics of Microspheres

Parameter	Resin	Glass
Trade name	SIR-Spheres	TheraSphere
Diameter	22 ± 10 μm	32 ± 10 μm
Specific gravity	1.6 g/dL	3.6 g/dL
Activity per particle	50 Bq	2500 Bq
Average number of microspheres per administered activity	40–80 million	1.2–8 million
Material	Resin with bound yttrium	Glass with yttrium in matrix