Development of Image-Guided Holmium-166 Microbrachytherapy and Clinical Results in Dogs

Holmium-166 microbrachytherapy is a novel, minimally invasive cancer treatment using radioactive microspheres that are injected directly into tumors. This enables a high local radiation dose within the tumor with minimal damage to surrounding healthy tissues. This treatment option offers alternative for patients in which conventional treatment like surgery or external radiotherapy are not deemed possible or effective, for example because of tumor characteristics, size and/or location. This PhD research demonstrated promising results in veterinary cancer patients. In dogs with soft tissue sarcomas, the treatment significantly reduced tumor size with limited side effects. The technique also proved feasible for treatment of a pituitary tumor. To improve administration precision, new carrier fluids for the microspheres were tested, ensuring better microsphere distribution within the tumor. Additionally, a new method was developed to accurately measure and monitor radiation dosage during treatment based on CT-images. These findings support holmium-166 microbrachytherapy as a safe and effective treatment option for inoperable or challenging tumors. Based on these results, the technique can be further optimized and clinically validated with advanced planning and administration devices. Combined with continued research and standardized clinical trials, this technique may also be a valuable treatment option in human oncology for treating challenging cancers such as brain or pancreatic tumors, for which studies are currently ongoing.