Determination of effective half-life of 131I in thyroid cancer patients using remote dose-rate meter

Abstract

BackgroundContinuously monitored external dose-rate signals from remote dose-rate meters (DRMs) were analyzed to determine the effective half-life (Teff) of 131I in differentiated thyroid cancer (DTC) patients. The aim is to gain novel understanding of the excretion of radioactive iodine (RAI) in DTC patients and to demonstrate that a remote DRM system can be reliably used for real-time monitoring of external dose-rates of DTC patients.Methods110 DTC patients who received postoperative RAI therapy between September 2018 and February 2023 in Turku University Hospital were studied retrospectively. The external dose-rates of the patients were continuously monitored during their hospitalization with a remote DRM fixed in the ceiling of the isolation room. Generalized linear mixed model (GLMM) was used to analyse the association between logarithmical Teff and patient characteristics.ResultsThe median Teff for all patients was 12.60 h (Q1: 10.35; Q3: 14.75 h). Longer Teffs were associated with higher BMI (p = 0.004), lower GFR (p < 0.001), and diabetes (p = 0.007). Our study also revealed that neither age nor subsequent RAI therapies have a significant impact on the whole body Teff (p = 0.522 and p = 0.414, respectively).ConclusionPatients with higher BMI, decreased GFR, or diabetes have a longer whole-body Teff of 131I. Ceiling-mounted remote DMRs can reliably be used to determine patient’s Teff. Since Teff values vary among patients, ceiling-mounted meters can be used to optimize the length of radiation isolation period at the hospital while improving patient comfort and staff efficiency.