High-Dose Radioimmunotherapy with 90Y- Ibritumomab Tiuxetan: Comparative Dosimetric Study for Tailored Treatment

High-dose 90Y-ibritumomab tiuxetan therapy and associated autologous stem cell transplantation (ASCT) were applied after dosimetry. This paper reports dosimetric findings for 3 different methods, including image corrections and actual organ mass corrections. Our first goal was to identify the most reliable and feasible dosimetric method to be adopted in high-dose therapy with 90Y-ibritumomab tiuxetan. The second goal was to verify the safety of the prescribed activity and the best timing of stem cell reinfusion. Methods: Twenty-two patients with refractory non-Hodgkin’s lymphoma were enrolled into 3 activity groups escalating to 55.5 MBq/kg. A somewhat arbitrary cutoff of 20 Gy to organs (except red marrow) was defined as a safe limit for patient recruitment. ASCT was considered of low risk when the dose to reinfused stem cells was less than 50 mGy. 111In-Ibritumomab tiuxetan (185 MBq) was administered for dosime