MIRD Dose Estimate Report No. 20: Radiation Absorbed-Dose Estimates for

Absorbed-dose calculations provide a scientific basis for evalu-ating the biologic effects associated with administered radio-pharmaceuticals. In cancer therapy, radiation dosimetry supports treatment planning, dose-response analyses, predic-tions of therapy effectiveness, and completeness of patientmed-ical records. In this study, we evaluated the organ radiation absorbed doses from intravenously administered 111In- and 90Y-ibritumomab tiuxetan. Methods: Ten patients (6 men and 4 women) with non-Hodgkin lymphoma, cared for at 3 different medical centers, were administered the tracer 111In-ibritumomab tiuxetan and assessed using planar scintillation camera imaging at 5 time points and CT–organ volumetrics to determine patient-specific organ biokinetics and dosimetry. Explicit attenuation correction based on the transmission scan or transmission mea-surements provided the fraction of 111In-administered activit