Science Behind SIR-Spheres

Blood Supply to the Liver

• Dual blood supply to the liver – hepatic artery + portal vein
• Tumors >2 cm draw >80% blood from the hepatic artery
• Normal liver parenchyma draws >80% blood from the portal vein

Hepatic artery supplies 90% of tumor; only 10% to normal liver

Specifications: 

• Resin particles 20-40 microns in diameter (avg: 32 microns)

• Y⁹⁰ = pure beta emitter chemically bound

• Max tissue penetration is 11 mm (avg 2.5 mm)

• Half life- 62.4 hours (~2.5 days)

• 94% of radiation dose is delivered within 11 days

• Low radioactivity per sphere (50Bq/sphere)

• Easily suspended in water-specific gravity of saline

• Slightly embolic

• Dose extracted from bulk individual dose

Entrapment of SIR-Spheres in Vascular Bed

SIR-Spheres Delivery Kit

Administration Technique: 2nd Outpatient Admission

SIR-Spheres Being Infused into the tumor