Biokinetics and dosimetry of target-specific radiopharmaceuticals for molecular imaging and therapy

Molecular imaging techniques directly or indirectly monitor and record the spatiotemporal distribution of molecular or cellular processes for biochemical, biologic, diagnostic or therapeutic applications. Te-99m-HYNIC-TOC has shown high stability both in vitro and in vivo and rapid detection of somatostatin receptor-positive tumors. Therapies using radiolabeled anti-CD20 have demonstrated their efficacy in patients with B-cell non-Hodgkin's lymphoma (NHL). The aim of this study was to establish biokinetic models for Te-99m-HYNIC-TOC and Re-188-anti-CD20 and to evaluate their dosimetry as target-specific radiopharmaceuticals. The OLINDA/EXM code was used to calculate patient-specific internal radiation dose estimates. Tc-99m-HYNIC-TOC images showed an average tumor/blood ratio of 4.3 +/- 0.7 in receptor-positive tumors with an average effective dose of 4.4 mSv. Dosimetric studies indicated that after administration of 5.8 to 7.5 GBq of Re-188-anti-CD20 the absorbed dose to total body would be 0.75 Gy which corresponds to the recommended dose for NHL therapies.