Response to “Critique and Discussion of ‘Multicenter Evaluation of Frequency and Impact of Activity Infiltration in PET Imaging, Including Microscale Modeling of Skin-Absorbed Dose’”

Abstract

limited quantitative accuracy of dosimetry based on planar scans. A SPECT/CT-based dosimetry study is already in preparation. Consequently, we saw no need to report preliminary results, which soon will become obsolete anyway. The other reason is the challenging interpretation of dosimetry data in predicting clinical consequences of systemic radioligand therapy. The latter issue is now addressed by Pretze et al., who mention various physical and radiation biologic aspects of this theme. We appreciate receiving such an instructive letter, stimulating a fruitful academic discussion.First, Pretze et al. mention further radionuclides that could serve as alternatives to 177 Lu. Indeed, the amount of 176 Yb that is needed for the production of high-specific-activity 177 Lu without 177m Lu impurities (half-life, 161 d) is limited. Consequently, the costs for producing no-carrier-added 177 Lu are relatively high. Routine availability of