Radiation safety assessment of the radiopharmaceutical «Albumin microspheres 5-10 μm, labeled with Re-188» during radiosynovectomy of the knee joint

Radiosynovectomy of the knee joint may be accompanied by side radiation effects on the patient’s healthy organs and tissues, which must be correctly taken into account for the further introduction of this method into widespread practice. The aim of the study is to evaluate the radiation safety of the radiopharmaceutical “Albumin microspheres 5-10 μm labeled with 188Re” (“AMS 5-10 μm, 188Re”) for patients suffering from chronic synovitis of the knee joints, resistant to standard therapy. A cytoge-netic examination was carried out on 23 patients (12 men and 11 women) suffering from recurrent synovitis of the knee joints, resistant to standard therapy, including intra-articular administration of glucocorticoids. The examined patients received therapy with the administration of 370, 555, 740 and 925 MBq of radiopharmaceutical “AMS 5-10 μm, 188Re” into one knee joint. Side radiation effects were investigated using induction of chromosomal aberrations in peripheral blood lymphocytes. A total of 66 blood samples (BS) were analyzed. BSs were taken from all patients before administration (control, 23 BS) and then 1 day (1 BS), 3 days (22 BS), 23 days (5 BS) and 28 days (15 BS) after injection. For biological dosimetry based on the frequency of aberrations, we used our own calibration dose dependence in the form of a linear-quadratic model, taking into account effect of dose rate. The results of a cytogenetic examination showed that the frequency of chromosomal aberrations ob-served after administration of radiopharmaceutical slightly exceeds control and does not depend on the value of the introduced activity in the range of 370-925 MBq. The side effects of radiation from the administration of radiopharmaceutical are safe, since the frequency of induced chromosomal aberrations does not exceed the spontaneous level in healthy donors. Biodosimetry assessment of the whole body adverse dose in the examined patients varies within the range of 104-182 mGy with an upper 95% confidence limit in the range of 410-521 mGy. The results of the study showed that side radiation exposure during radiosynovectomy with radiopharmaceutical “AMS 5-10 μm, 188Re” does not pose a danger, since the adverse dose does not exceed the exposure from natural background radiation.