Ho-166- Microspheres

¹⁶⁶Ho-microspheres is a product developed at the University Medical Center of Utrecht (The Netherlands) on the basis of microparticles loaded with ¹⁶⁶Ho and sold under the name ¹⁶⁶Ho-QuiremSpheres®. These particles are obtained by direct activation of ¹⁶⁵Ho pre-loaded poly-L-lactic acid (PLLA) particles (mean diameter 30 µm) using a direct, high-Neutron flux from a reactor. The Specific activity is limited by the maximum time of Irradiation as microspheres degrade under Neutron beams above one hour.

This product was filed as a Brachytherapy drug and as such still to be considered as a medical device. QuiremSpheres® received CE mark in April 2015.

¹⁶⁶Ho-microspheres are analogues of ⁹⁰Y-microspheres and intended for implantation into hepatic tumors by delivery via the hepatic artery to be used in patients with unresectable liver tumors.

Target/Mechanism: Brachytherapy

Leading Emitter: beta electrons (β^–)