الملخص

Abstract In this research the absorbed dose by the thyroid gland of radioiodine 131I during treatment of the thyroid cancer after total or partial remove of the thyroid gland by operation, the radioiodine is concentrated in the un removed parts of the gland tissue depending on stage and type of disease. The thermoluminescence dosimeters TLDs are used for measuring the absorbed dose for its good efficiency in detecting alpha and gamma rays. High radiation doses was found in un removed regions, and low doses in the partial removed regions, in case of the total remove of the gland readings were lower over all the gland. Moreover much lower dose was found after second treatment by radioiodine, these measurements were welcomed by doctors of radiotherapy. Also by measuring the transmitted gamma rays from the frontal and dorsal parts of the neck it is found that the transmitted rays from the frontal part is about more than that from the dorsal part which indicate possible absorption and scattering by tissues and vertebral and also by the spinal cord, this later measurement help to consider the low possible risk of treatment by radioiodine. Keyword: TLDs، 131I, gamma ray, treatment by radioiodine, Radiation Dose.