Thyroid protection for 123I meta-iodobenzylguanidine and 123I ioflupane (DaTScan) diagnostic imaging: historical context, current evidence, and clinical perspectives.

Unintended radiation exposure to the thyroid following administration of iodine-containing radiopharmaceuticals remains a clinical concern, primarily due to in-vivo metabolism leading to the release of free iodide or the presence of unbound iodine in the radiopharmaceutical preparation. Although several recommendations for thyroid protection are currently in use, the robust scientific evidence underpinning these practices remains limited, with available data insufficient to define an optimal approach with confidence. In this editorial, we briefly review the rationale for thyroid protection, summarise existing recommendations, and discuss future directions, with particular emphasis on 123I meta-iodobenzylguanidine and 123I ioflupane (DaTScan) imaging. We argue that while standardised clinical operating procedures are necessary to mitigate presumed long-term risks associated with nontarget thyroid irradiation, a more adaptive, evidence-based strategy may offer greater flexibility to accommodate individual patient characteristics and clinical needs.