Pengembangan Metode Cepat Pengukuran 131I di Organ Tiroid Staf Kedokteran Nuklir Menggunakan Surveimeter

Iodine-131 (131I) is an unsealed and volatile radioactive source that has the potential to contaminate air around the work area of nuclear medical staff. Potential contamination needs to be monitored so that the dose received by staff does not exceed the dose limit of radiation workers. This research developed a rapid method for measuring 131I in the thyroid organ of nuclear medical staff using a beta–gamma surveymeter with a Geiger Muller (GM) detector. The Ranger surveymeter was calibrated using anthropomorphic phantoms of adult male and female thyroids created with a 3D printer and injected with a standard 131I with an initial activity (A0) of 4.44 kBq. Exposure rates were measured over 5 days. The calibration factors for male and female thyroid phantoms were 15.47±0.24 μSv/h/kBq and 10.09±0.25 μSv/h/kBq, and the detection limits were 77±3 Bq and 121±21 Bq. Based on the measurement results of 5 nuclear medicine staff, information was obtained that the level of 131I contamination in the thyroid organ was between undetectable and 309 Bq. Low levels of contamination (below the detection limit) were present in measurements of radiographers, radiation protection officers (RPO), and cleaners. The contamination levels above the detection limit were present in nurse and radiopharmacist measurements, with estimated internal doses of 0.238–0.927 mSv/year. The level of contamination increased during the patient therapy day of 131I. This potential can be minimized by installing 131I air cleaners in the therapy room and hotlab. Keywords: 131I, contamination, nuclear medicine, radiation protection, surveymeter, thyroid phantom.