[Radioiodine testing in clinical routine: Status in Germany 2021].

Abstract

Introduction and aim: According to the German guideline on Radiation Protection in Medicine, the activity to be applied for radioiodine therapy of benign thyroid diseases is determined for each patient by means of the radioiodine test (RJT). The aim of this study is to record the different parameters of the RJT.

Material and methods: A web-based questionnaire was sent to all nuclear medicine departments in Germany via the DGN office. Parameters regarding tracer and activity, type of probe measurement, number and timing of measurements, use of fixed effective half-lives (eHWZ), calculation model and organ doses were requested. An assessment of continuous measurement of the thyroid iodine uptake over seven days by a wearable probe system was also requested.

Results: 38 of 94 facilities responded to the questionnaire. Major differences in RJT implementation were found concerning the parameters number and timing of measurements, probe-patient distance, use of fixed disease-specific eHWZ, and intended organ dose. Despite the DGN Guideline and DIN 6861-1, 74% of the facilities still use the simplified Marinelli formula from the DGN Recommendation of 1998. Only 8% have switched to the two-compartment model. 84% of the institutions expect that a wearable probe system could improve the calculation of the radioiodine activity necessary for treatment, but only 57% expect an improvement in the therapeutic outcome.

Conclusions: The methodology of RJT in Germany is heterogeneous and still based on the "Marinelli method" in most institutions despite new guidelines and recommendations. A continuous measurement of the iodine kinetics using a wearable probe system could result in further improving the radioiodine test in addition to the newer calculation algorithms.