Abstract

YERA SIMANCA, Yoan; LOPEZ BEJERANO, Gladys M; RAMOS MACHADO, Dayana  and  ACOSTA RODRIGUEZ, Nancy. Monitoring intervals for the measurement of the radionuclides 125I and 129I in the thyroid gland. Nucleus [online]. 2014, n.55, pp.15-18. ISSN 0864-084X.

This paper shows the monitoring intervals that can be used in the Internal Contamination Laboratory of the Center for Radiation Protection and Hygiene for direct measurement of the radionuclides I-125 and I-129 in the thyroid gland. Two measuring systems were used, one of them with a scintillation detector and the other one with a Phoswich detector. Both detectors were placed inside a low background shielding chamber (2.5 x 2.5 x 2.5 m) coated with 15 cm of steel, 3 mm of lead, 1.8 mm of tin and 1.5 mm of copper. The minimum detectable activity for each system was calculated, and based on this, the applicable monitoring intervals were determined, so that an intake corresponding to 5 % of the Annual Intake Limit can be detected. The results showed that for the radionuclide I-125 all the intervals tested (120, 90, 60, 30, 14 and 7 days) can be used in monitoring both systems. In the case of the radionuclide I-129, only the intervals of 120, 90 and 60 days can be implemented by using the scintillation detector whereas for the Phoswich detector, all the tested intervals can be used

Keywords : iodine; monitoring; time interval analyzers; scintillation counters; activity levels.

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