Dosimetry of ¹³¹I-labeled anti-ferritin in hepatoma: A model for radioimmunoglobulin dosimetry

Dosimetric studies are reported for four hepatoma patients treated with ¹³¹I-labeled anti-ferritin following combination radiation and chemotherapy. Administered activities of radiolabeled antibody ranged from 93 to 157 mCi. Studies included liver and tumor volume calculations from sequences of computerized axial tomographic (CAT) scan slices, in-vivo gnantitation of radiolabeled antibody in the liver and tumor, determination of kinetic parameters of radioimmmioglubulin for liver, tumor, and the total body, and computation of dose rates (rad/boor) and dose (rad) for these tissues. Tumor volumes for these patients prior to the administration of radiolabeled antibody ranged from 370 to 920 cm³ and liver volumes from 900 to 1980 cm³. In-vivo quantitation, carried out 4 to 8 days following infusion of ¹³¹I-labeled anti-ferritin, demonstrated tumor-to-liver ratios of about 2:1 for the deposition of radioimmunoglobuBn in these tissues. Mean values of the effective half-life for radiolabeled antibody in the liver and tumor were 7.4 days and for total-body activity 3.6 days, respectively. For the four patients, the calculated ¹³¹I radiation dose for tumor tissue ranged from 1500 to 2200 rad, for liver tissue from 400 to 1000 rad, and for total-body irradiation (TBI) from 110 to 220 rad.