Dosimetry of intraperitoneally administered radiolabeled antibodies

Intraperitoneal and intracavitary radioimmunotherapy differ from other approaches of radioimmunotherapy in that high activity and dose gradients exist near the solution/tumor interface. Dose to tumor and normal tissue at the interface is a function of depth and is due to three major components: (1) the activity concentration of the administered radiolabeled antibody solution as a function of time within the compartment; (2) the spatial distribution of antibody/radionuclide complex as a function of depth and time as the biomolecules bind to and permeate tumor/normal tissues; and (3) the physical characteristics of the radionuclide in relation to depth of antibody penetration. In this review, the biological and physical aspects of intraperitoneally administered radiolabeled antibodies are discussed, and the state of experimental and calculational studies for this site is described. Areas requiring future investigation are examined, and recommendations are made regarding the type of measurements and calculations which are required for accurate dosimetry.