Dosimetric characteristics of a new 125 I brachytherapy source

Hematologic toxicity limits the radioactivity that may be administered for radiolabeied antibody therapy. This work examincs approaches for obtaining biodistribution data and performing dosimetry when the administered antibody is known to bind to a cellular component of blood, bone, or marrow. Marrow dosimetry in this case is more difficult because the kineties of antibody clearance from the blood cannot be related to the marrow. Several approaches for obtaining antibody kineties in The marrow are examined and evaluated. The absorbed fractions and S factors that should be used in performing marrow dosimetry are also examined and the effect of including greater anatomical detail is considered. The radiobiology of the red marrow is briefly reviewed. Recummendations for performing marrow dosimetry when the antibody binds to the marrow are provided.