⁹⁰Y SIR-Spheres Activity Measurement with New SIROS D-Vial Delivery Kit.

Area of Science:

• Nuclear Medicine
• Radiopharmacy
• Medical Physics

Background:

• A new Yttrium-90 (⁹⁰Y) SIR-Spheres delivery kit (SIROS D-vial) has been introduced, differing physically from the legacy V-Vial kit.
• Accurate activity measurement is crucial for effective and safe brachytherapy treatment.

Purpose of the Study:

• To establish optimal dose calibrator settings for assaying ⁹⁰Y SIR-Spheres activity in the new SIROS kit.
• To determine an accurate exposure-rate-to-activity conversion factor for the SIROS kit.

Main Methods:

• Eight SIROS D-vials with varying ⁹⁰Y activities were measured using dose calibrators and exposure-rate meters.
• Dose calibrator settings and conversion factors were evaluated for accuracy and reliability across a range of activities.

Main Results:

• Setting 51×10 on CRC-15R and CRC-55tR dose calibrators provides accurate (±0.5%) ⁹⁰Y activity estimation for the SIROS kit.
• An exposure-rate-to-activity conversion factor of 0.664 ± 0.003 GBq/(mR/h) at 30 cm was determined with high correlation (R² = 0.985).

Conclusions:

• Updated dose calibrator settings and conversion factors are necessary for the SIROS kit.
• Failure to update parameters can lead to an underestimation of ⁹⁰Y activity by approximately 10%.