Radio immunotherapy is one of the most important and effective therapies for
B-cell non Hoddgkin?s lymphoma treatment. Today, anti CD-20 antibodies
labeled with beta emitter radionuclides are used in radio immunotherapy.
Various radionuclides for labeling anti CD-20 antibodies have been studied
and developed for the treatment and diagnosis of malignancies. This paper
describes the preparation, bio-distribution and absorbed dose rate of 111In,
90Y, 177Lu, and 153Sm labeled anti CD-20 antibodies (rituximab) in human
organs, after injection to rats. The macro cyclic bifunctional chelating
agent, N-succinimidyl-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7,
10-tetraacetic acid (DOTA-NHS) for conjugation to antibody, was used to
prepare DOTA-rituximab. The conjugates were purified by molecular filtration,
the average number of DOTA conjugated per mAb was calculated and total
concentration was determined by spectrophotometric method. Radio-labeling was
performed at 40 ?C for 24 hours. After the quality control studies, the final
radioactive solution was injected intravenously into rats through their
tail vein. The tissue uptakes of each injection were measured. Then we
calculated S values for 177Lu and 153Sm by using specific absorbed fractions
and data used in the manner of radio-labeled analysis and dosimetry for
humans. The absorbed dose rate of each organ was calculated in the specific
time by medical internal radiation dose method with linear approximation in
the activity measurements.