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Sirtex SIR-Spheres - Model Y-90 -Resin Microspheres for Radioembolization Therapy
SIR-Spheres Y-90 resin microspheres are a medical device used in selective internal radiation therapy (SIRT), primarily for the treatment of inoperable liver tumors. These microspheres are based on yttrium-90, a radioactive isotope, and are injected directly into the hepatic artery, enabling targeted radiation delivery. The primary goal is to deliver high doses of radiation to the tumor while minimizing exposure to surrounding healthy tissue. Produced by Sirtex, a company specializing in innovative cancer therapies, these microspheres represent a significant advancement in the treatment of liver tumors, including metastatic colorectal cancer. They have been integrated into therapeutic protocols globally and provide an alternative for patients with limited surgical options. The technology requires a multidisciplinary approach, involving interventional radiologists, oncologists, and nuclear medicine specialists to ensure precise application and optimized outcomes.
SIR-Spheres Y-90 resin microspheres are a permanent implant and intended 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.
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
SIR-Spheres Y-90 resin microspheres 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
- 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 :
- SIR-Y001: 3 GBq or 81 mCi per vial +/- 10% at the time of calibration
- SIR-Y002: 1.8 GBq or 48.7 mCi per vial +/- 10% at the time of calibration
- No. of microspheres per vial :
- SIR-Y001: ~44 million microspheres (with a standard deviation of 2.6 million) FR-006
- SIR-Y002: 27.3 million microspheres (MS-TR-008)