Occupational exposure and radiobiological risk from thyroid radioiodine therapy in Saudi Arabia

Abstract

Worldwide, thyroid cancer accounts for some 10% of total cancer incidence, most markedly for females. Thyroid cancer radiotherapy, typically using 131I (T1/2 8.02 days; β− max energy 606 keV, branching ratio 89.9%), is widely adopted as an adjunct to surgery or to treat inoperable cancer and hyperthyroidism. With staff potentially receiving significant doses during source preparation and administration, radiation protection and safety assessment are required in ensuring practice complies with international guidelines. The present study, concerning a total of 206 patient radioiodine therapies carried out at King Faisal Specialist Hospital and Research Center over a 6-month period, seeks to evaluate patient and occupational exposures during hospitalization, measuring ambient doses and estimating radiation risk. Using calibrated survey meters, patient exposure dose-rate estimates were obtained at a distance of 30-, 100- and 300 cm from the neck region of each patient. Occupational and ambient doses were measured using calibrated thermoluminescent dosimeters. The mean and range of administered activity (AA, in MBq) for the thyroid cancer and hyperthyroidism treatment groups were 4244 ± 2021 (1669–8066), 1507.9 ± 324.1 (977.9–1836.9), respectively. The mean annual occupational doses were 1.2 mSv, that for ambient doses outside of the isolation room corridors were found to be 0.2 mSv, while ambient doses at the nursing station were below the lower limit of detection. Exposures to staff from patients being treated for thyroid cancer were less compared to hyperthyroidism patients. With a well-defined protocol, also complying with international safety requirements, occupational exposures were found to be relatively high, greater than most reported in previous studies.

Assessment of Patient and Staff Annual Effective Doses at a Nuclear Medicine Department during Bone Scans

“…Additionally, UNSCEAR, encouraged member states to provide data regarding patients and staff exposure due to the lack of reported values [1]. Limited studies were reported regarding occupational exposure during nuclear medicine examination in Saudi Arabia [10] [17]. The prior investigations revealed significant dosage variability due to variations in scanning methodology, perception methods, and NM technologist expertise.…”

Assessment of thyroid gland hormones and ultrasonographic abnormalities in medical staff occupationally exposed to ionizing radiation

“…Radioiodine results in a significant β-decay component. Contrariwise, for nuclear medical personnel, γ-emission represents the primary source of external exposure [ 29 ]. Radioiodine emitted radiation directly induces DNA damage or generates reactive oxygen species (ROS).…”

Application of a tungsten apron for occupational radiation exposure in nursing care of children with neuroblastoma during 131I-meta-iodo-benzyl-guanidine therapy

“…Even with the use of the tungsten apron, the results might have been affected by basic radiation protective factors such as exposure time and distance from the child. Radiation exposure can be accumulated over time with prolonged exposure, and a greater distance from the radiation source can reduce radiation exposure 23 – 25 .…”

“…The radiation doses of some caregivers of younger patients were > 5.0 mSv. On the other hand, in the case of 131 I therapy for thyroid diseases, the most famous nuclear medicine treatment, a medical worker’s annual occupational radiation exposure is < 2.2 mSv 25 , 26 . The occupational dose of up to 0.26 mSv per 131 I-MIBG therapy session in this study is considered to be higher than that of 131 I treatment.…”