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SIR-Spheres® Y-90 resin microspheres

About SIR-Spheres

About SIRT

SIR-Spheres Y-90 resin microspheres are a permanent implant and for single use only.

The high number of microspheres provides a uniform radiation distribution, enabling treatment of solitary and multifocal liver tumors.1–3

With a specific density close to that of red-blood cells,1 they are carried by the blood flow, penetrating deep into the tumor microvasculature.

SIR-Spheres can therefore be delivered in a slow, deliberate manner:
  • to achieve an even distribution
  • to maximize the number of microspheres delivered
  • to optimize tumor coverage - even in patients with extensive disease
Yttrium-90 has two inherent safety features for staff and patients:
  • the minimal penetration depth of beta radiation emissions through tissue and air
  • the relatively short half-life of 64.1 hours
Product Features
Manufacturer Sirtex Medical Pty Ltd
Isotope Yttrium-90
Decay product Zirconium-90
Composition Resin (sulfonated divinyl benzene-styrene copolymer)
Specific density 1.125-1.6 g/ml (comparable to red blood cells)
Diameter 32±10 µm
T1/2 64.1 h (94% within 11 days)
Penetration in tissue 2.5 mm (mean)
Presentation of activity Single dose size containing 3.0 GBq ± 10% of Y-90 at calibration date & time in 5 ml water for injection, moist sterilized.
No. of microspheres per vial 44 (± 2.6) million


Additional Product Information

  1. Sirtex internal data
  2. Burrill J et al. J Nucl Med Radiat Ther 2011; 2:107. doi:10.4172/2155-9619.1000107.
  3. Chiesa et al. J Nuc Med Molmaging 2011; 55: 168–197.