Intratumoural treatment with holmium-166

Holmium-166 microspheres were initially developed in order to perform radioembolization[Link naar radioembolisatie]. However, besides radioembolization, holmium-166 microspheres can also be used as a platform technique wherein holmium-166 radioactive microspheres are placed in a controlled manner directly inside the tumour. Due to the small penetration depth of the radioactivity, tumours can be irradiated in a relatively accurate manner and with a high local dose. The radioactive holmium microspheres are an attractive medical device for the intratumoural approach since they are paramagnetic which allows quantification with SPECT and MRI. Furthermore, the relatively high density of the particles allow the visualization of the microspheres with CT. As a result of the multimodal imaging capabilities the distribution of the microspheres, and thus the therapeutic range can be evaluated.


With the defined technique tumours can be reached by needle like, brain, pancreatic and head & neck tumours. In the study “Image-guided treatment of brain malignancies with radioactive holmium microspheres” an administration and monitoring system for controlled administration of microspheres in the tumour will be developed as an alternative minimally invasive treatment of brain malignancies. In this project the feasibility of different carrier fluids and microspheres for intratumoural injection in brain malignancies will be investigated. In addition, an administration system for controlled intracranial holmium-166 microspheres and an effective imaging-based dosimetry technique for real-time dose monitoring will be developed. The system will be tested in phantoms and veterinary patients. The phantom experiments will partially take place at the Medical Innovation & Technology expert Center (MITeC). If successful, a feasibility study will be set up for a clinical intratumoural application.

Funding and collaboration

This project is funded by NWO and is in collaboration with the Faculty of Veterinary Medicine at Utrecht University.