64 Cu-/ 177 Lu-Cetuximab Theranostic Pair: May the Single 64 Cu-Cetuximab Diagnostic Scan Be Acquired at Any Time After Injection?

Two independent equations were recently proposed for estimating Lu-cetuximab cumulative activity, in a preclinical situation, from an initial Cu-cetuximab diagnostic scan acquired at peak time of decay-uncorrected () or decay-corrected () time-activity curve of trapped Cu-cetuximab, respectively. The standard uptake ratio (SUR) measured at or turned out to be a key metric in each equation, respectively. However, acquiring the diagnostic scan at or might be a limitation of the proposed method. Therefore, in an attempt to overcome this limitation, this note aims at theoretically investigating whether SUR() and/or SUR() could be derived from a diagnostic scan acquired at any time postinjection.