Correlation of external dose rate with whole body clearance estimation in radioiodine therapy for rhTSH and THW patients

Abstract

The efficacy of recombinant human thyroid stimulating hormone (rhTSH) and thyroid hormone withdrawal (THW) in estimating the whole body radioactive clearance was done by measuring the external dose rate for both stomach and neck at 1 m and 5 cm distances, respectively. Two groups of subjects, which were 34 patients with THW who stop the thyroxin uptake for 1 month and 3 patients with rhTSH injection at 24 and 48 h prior to radioiodine therapy, have been selected. Sequential dose rate at 1 m and 5 cm distances from stomach and neck was measured in these patients using a digital auto-ranging beta-gamma survey meter instrument for 0, 12, 24, 36 and 48 h after I-131 ingestion. The initial activities were ranged from 3700 to 5550 MBq. Significant statistical value of Mann Whitney Test (P < 0.05) at 24, 36 and 48 h proved the radioactive clearance of rhTSH injection was faster than patients with THW method, where the I-131 kinetics might be more effective in promoting the drug to the target tissues after 24 h. Patient with rhTSH injections could reduce the individual dose to organs and allowed to be discharged earlier than the patient with THW method.