A computer simulation study of optimal thyroid radiation protection during investigations involving the administration of radioiodine-labelled pharmaceuticals.
The administration of iodide for thyroid blocking is now known to carry its own risks, at least in certain categories of patients. We have therefore made a theoretical study by computer simulation of the efficacy of various thyroid blocking regimes. In the case of injected 125I- or 131I-iodide, substantial thyroid protection may theoretically be achieved by a single oral dose of inorganic iodide, for example a 90% reduction in radiation dose is produced by only 20 mg iodide. Repeating the initial blocking dose is of little value. A single blocking dose, however, affords poor protection against radioiodine released from labelled plasma proteins. Both for short-lived proteins such as fibrinogen, and for the longer-lived proteins such as albumin, the optimum dosage schedule appears to be stable iodide given daily for two to three weeks. For instance, 10 mg daily for a fortnight will reduce thyroid irradiation by a factor of ten following injection of 125I-fibrinogen.
D000418:Albumins / Q000378:metabolism; D003201:Computers; D005340:Fibrinogen / Q000378:metabolism; D006801:Humans; D007454:Iodides / Q000008:administration & dosage; D007457:Iodine Radioisotopes / Q000008:administration & dosage*; D008954:Models, Biological; D011829:Radiation Dosage; D011835:Radiation Protection; D012306:Risk; D013961:Thyroid Gland / Q000378:metabolism / Q000528:radiation effects*
D000418:Albumins; D007454:Iodides; D007457:Iodine Radioisotopes; D005340:Fibrinogen