Outpatient Yttrium-90 microsphere radioembolization: assessment of radiation safety and quantification of post-treatment adverse events causing hospitalization.

Quantification of post-interventional adverse events of outpatient SIRT leading to hospitalization and quantification of radiation exposure. In this single-center, retrospective cohort study, we reviewed 212 patients treated with SIRT ( <sup>90</sup> Y-microspheres) for primary and secondary liver malignancies. We searched for adverse events (AEs) and serious adverse events (SAEs), defined as AE's causing hospitalization. Additionally, radiation exposure was measured in 36 patients. Seven patients had an SAE (3.3%), four patients had AE without readmission/hospitalization (1.9%) and 201 patients had no complications (94.8%). The mean ambient dose rate at 1 m distance from the source after administration of <sup>90</sup> Y-microspheres was 1.88 µSv/h ± 0.74 (± SD) with a range from 4.3 to 0.2 µSv/h. Outpatient radioembolization with <sup>90</sup> Y-microspheres is safe and requires hospitalization only in a very small number of patients. The mean dose rate was low and met the national conditions for outpatient treatment (< 5 µSv/h)