Radioactive concentration of 131I in the air of treatment workplaces for differentiated thyroid cancer with sodium iodide 131I oral solution / 中国辐射卫生

ABSTRACT

Objective To study the radioactive concentration of 131I in the air of workplaces where sodium iodide [131I] oral solution was administrated for patients with differentiated thyroid cancer (DTC) in the Department of Nuclear Medicine, and to estimate the internal radiation dose to the staff. Methods Workplaces of radioiodine 131I therapy for DTC patients in the Department of Nuclear Medicine of a hospital were investigated. Air samples in 131I administration areas and treatment wards were collected respectively and were measured by low-background gamma-ray spectrometry to calculate the activity concentration of 131I in the air and to further estimate the internal radiation dose to staffs. Results The activity concentration in the 131I administration area within the first 3 h of administration was 3～187 Bq/m3. During administration and within the first 3 h of administration, the staff exposed in the administration area for 5～30 min received an internal radiation dose of 0.08～0.50 μSv and 0.00～0.04 μSv, respectively. The highest activity concentration of 131I in the air of the ward was measured on the day of administration, reaching 3091 Bq/m3. After patients were discharged, the activity concentration in the ward gradually decreased to 10～242 Bq/m3 within 48 h. Within 48 h after patients were discharged, the staff exposed in the ward for 5～30 min received an internal radiation dose of 0.01～14.11 μSv. Conclusion A high activity concentration of 131I in the air was recorded during administration for DTC patients in radioiodine 131I therapy, and thus we recommend remote instructed administration or administration through a shielded window. We also recommend that non-treatment related personnel except medical staffs should not enter the ward during patients’ hospitalization at which the activity concentration of 131I in the ward was the highest. After patients were discharged, a delayed entry into the ward is recommended to reduce the internal radiation dose.