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Table 1 Physical characteristics of MAA and 90Y microspheres

From: EANM dosimetry committee series on standard operational procedures: a unified methodology for 99mTc-MAA pre- and 90Y peri-therapy dosimetry in liver radioembolization with 90Y microspheres

  99mTc-MAAΔ Resin spheres Glass spheres
Commercial name   SIR-Spheres® TheraSphere®
Manufacturer   Sirtex Medical Boston Scientific
Diameter (μm) ± standard deviation (μm) 31.2; Range (10–100)
non spherical
32.5 ± 2.5; range (20–60) 25 ± 5
Specific gravity n/a 1.6 g/mL 3.6 g/mL
Vial activity (GBq) 1.5 (α)–3.7 (β) 2.5–10** From 3* to 20*, with 0.5 step
Activity per particle (Bq) 333 (α)–822 (β) 42–166** 4354*, 1539, 544
Millions of particle per GBq 3 (α)–1.2 (β) 24–6** 0.23*, 0.65, 1.84
Millions of particles in a typical administration 0.3–0.7 1.2 GBq
28.8–7.2** millions
2.6 GBq
1.7 4.8 millions
Stasis phenomenon (backflow, jammed injection) Never reported Reported Never reported
Material Human albumin Resin with 90Y on surface 90Y in glass matrix
Shelf life 6 h from labelling (− 4, + 1) days 12 days
Handling vial for dispensing Required Required Not required
Vial fractionation in syringe Required Required Not required
Iodinated contrast medium during administration Not required Recommended Not required
  1. (α) 4.5 millions of MAA labelled with 1.5 GBq
  2. (β) 4.5 millions of MAA labelled with 3.7 GBq
  3. * Measured, at the reference date. [18]
  4. **Depending on the injection time. Resin microspheres can be delivered up to 4 days before the calibration date, when vial activity is 10 GBq. This means that the planned activity can be injected with one third of the number of particles with respect to the calibration date (https://www.sirtex.com/eu/clinicians/flexdose-delivery-programme/)
  5. Four days after the reference time.
  6. Eight days after the reference time.
  7. Δwww.nuclearonline.org/PI/mallinckrodt%20MAA.pdf, www.accessdata.fda.gov/drugsatfda_docs/label/2009/017881s010lbl.pdf
  8. https://www.sirtex.com/media/169513/pi-ec-14-spheres-ifu-eu-row.pdf
  9. https://www.bostonscientific.com/en-US/products/cancer-therapies/therasphere-y90-glass-microspheres.html