I'm tracking a set of medical images in a logbook-type application, and am having a problem with how to model my records. The problem is that for every group of images collected, there are two similar, but distinct ways of recording data about a given scan: the first being done by a study coordinator at the scanner, writing description, order and comments about each image, and the second by scanning the actual images' metadata a day or so later when they are transferred to us and have become available. Both models (the image metadata and the hand-written log) are about the same thing (each image), but are entered at different times.
My question is: How should I connect the two models? Since they would both be the same order belonging to the same scan, I can match them up programmatically, but that seems like it would be a lot of overhead, and simultaneously not very flexible. I could connect them with a join table or a foreign key for one or the other, but that might lead to some internal inconsistencies. I can't model them as exactly the same model, because there are some extra tasks that behave like images but aren't images, in the hand-written log, and they don't have images or metadata.
Is it better just to be rigid and link them programmatically, without any keys relating them? The link would depend on the data being correct (but I guess that's always the case).