ePrints

Should we reconsider blocking the thyroid for ¹²³I-Ioflupane studies in elderly patients: quantifying radiation dose to the unblocked thyroid and implications for clinical practice

Lookup NU author(s): Dr Salman RazviORCiD

Downloads

Full text for this publication is not currently held within this repository. Alternative links are provided below where available.

Abstract

Objectives: To measure the absorbed dose to the thyroid in patients injected with ¹²³I-Ioflupane where the thyroid was not blocked with prophylaxis to investigate whether thyroid blocking should be limited to younger patients. This risk from the additional absorbed dose to the thyroid was then compared to the risk from iodine overdose through ingestion of the iodide prophylaxis, resulting in iodine-induced hyper/hypothyroidism (IIH). Methods: A cohort of patients (n = 30) who did not receive thyroid prophylaxis underwent static thyroid imaging 3 h after ¹²³I-Ioflupane administration. The measured thyroidal uptake of free ¹²³I was then extrapolated to peak uptake time (24 h post-administration). This value was used to calculate cumulated activity in the thyroid and thus thyroid-thyroid absorbed dose D(r_thy←r_thy) using the relevant S-value in the MIRD method. Results: Mean D(r_thy←r_thy) was found to be 13.6 mGy with an SD of 8.8 mGy; this would contribute an additional 0.5 mSv to the effective dose. Conclusion: ARSAC recommends in its Notes for Guidance prophylactic thyroid blocking if the absorbed dose to the thyroid is >50 mGy; the maximum thyroid dose in this study cohort was 36.3 mGy. With risk from IIH and its associated cardiac complications increasing with age, this study suggests that iodide prophylaxis with ¹²³I-Ioflupane should be reconsidered for elderly patient.

Publication metadata

Author(s): Morton DWA, Vennart N, Slinger H, Gannon M, Razvi S, Bartholomew P

Publication type: Article

Publication status: Published

Journal: Nuclear Medicine Communications

Year: 2024

Volume: 45

Issue: 2

Pages: 108-114

Print publication date: 01/02/2024

Online publication date: 30/10/2023

Acceptance date: 09/10/2023

ISSN (print): 0143-3636

ISSN (electronic): 1473-5628

Publisher: Wolters Kluwer Health, Inc.

URL: https://doi.org/10.1097/MNM.0000000000001785

DOI: 10.1097/MNM.0000000000001785

PubMed id: 37901928

Altmetrics

Share