Instead of the value of evaluating a single scan, what about determinations made from evaluating regular deltas between images?

As a layperson, I'm mostly familiar with the concept of "get scanned, and a professional evaluates it"... are there scenarios where the approach of "imaging every few weeks, to make decisions based on trends" is currently done?

(From reading other comment threads here, I suspect the general answer is: other body-scanning startups have proposed the same thing, and it hasn't made sense)

As an aside, I could probably benefit from allergy shots, but the idea of having a regularly scheduled errand to do during the workweek is pretty unappealing, so I never seriously consider it.