Handheld survey meter is commonly used to measure radiation exposure in patients receiving radioiodine (RAI) therapy prior to discharge. However, it requires staff to be in close proximity to the patients, potentially increasing radiation exposure towards staff and lack of ability to provide real-time monitoring. This study introduces a ceiling-mounted Geiger Müller (GM) detector, aiming to evaluate the effectiveness in assessing radiation exposure compared to handheld survey meter in clinical settings.

74 patients who received high-dose RAI therapy (80 mCi, 100 mCi and 150 mCi) were retrospectively selected in this study. Radiation exposure at 48 h post-RAI intake was measured at a consistent 1-m distance from neck region of patients using both the ceiling-mounted GM detector and handheld survey meter in the isolation room and the results were being compared. Additionally, the radiation exposure was measured in real-time using ceiling-mounted GM detector.

A maximum variation of 9.9 ± 2.7% was observed between the radiation exposure measurements from the detectors. The ceiling-mounted GM detector had a statistically significant relationship with handheld survey meter using Pearson’s correlation test (p-value < 0.001). The ceiling-mounted GM detector recorded radiation exposure rates under 50 µSv/hr at 25, 29 and 37 h following 80 mCi, 100 mCi and 150 mCi RAI doses, respectively.

Both detectors provided consistent and comparable results for measuring radiation exposure at 48 h post-RAI intake. The ceiling-mounted GM detector demonstrated reliable real-time monitoring capabilities, offering a practical and effective alternative to handheld survey meter post-therapy radiation monitoring.