3. 6-7 days after infusion of the dosimetric dose, following urination Therapeutic Dose: The total body residence time, derived from total body gamma camera counts obtained at the 3 time points, was used to calculate the iodine-131 activity (mCi) to be administered to deliver the therapeutic total body irradiation dose of 65 or 75 cGy. The therapeutic step was administered 7-14 days after the dosimetric step and consisted of tositumomab 450 mg followed by an activity (mCi) of iodine-131 calculated to deliver 75 cGy or 65 cGy of total body irradiation, depending on platelet count, and 35 mg of tositumomab.