I am not a doctor and even if I were you should discuss this with your doctor(s). I have dealt with unexplained iron deficiency for months, which turned out to be due to a g.i. issue, and required iron infusions until the cause was uncovered.
Fist, anemia can be caused by other deficiencies, such as low vit. b, and low folic acid. Presumably, your doctor determined that low iron is the cause of yours. Simply focusing on the iron #'s is not enough to make a diagnosis. And as far as "iron studies" they also check ferritin and TIBC (binding capacity). All of these things contribute to revealing what could be going on.
If the iron deficiency continues though (becoming "unexplained"), it can be a painstanking process to uncover the cause. E.g. it could be a g.i. issue, anemia of inflammation/chronic disease, an ulcer, celiac, a malginancy, occult bleeding, and so on.
I'm curious why your doctor(s) are looking to do a CT scan now, rather than say, colonscopy/endoscopy, MRE (MRI of your small intestine), and then if there's still no explanation, a capsule endoscopy. That's not to say you shouldn't do the CT, but my understanding is that's not usually what they do first, and it's not even the ideal modality (radiation exposure and not a higher diagnostic yield than the other stuff).
In any case, like people said, I wouldn't worry - the main thing is to just go through the process, do what you doctors tell you for treatment, and have patience, since, it can take a while to work through all the imaging and tests, to get at what's going on.
And while it's good to be attentive to dietary iron intake and nutrition generally, it's pretty rare for a male to have IDA soley due to diet (regardless of vegan, etc.).
And by the way, at one point, after months of feeling terrible, I did ask my doctor about EPO (after already having had multiple rounds of iron infusions) - when my HB was several points below normal - he said no, he normal doesn't give it for i.d.a. like I had, that it has potential side effects such as stroke.
Anyway, while I understand your curiosity, you should be posing these questions to your primary care doctor and possible a gastro and/or hematologist as well. Even if there are doctors responding to your question(s), they're not your doctor, they don't know your medical history.
Oh - and supplementing with oral iron if you don't need it is problematic - it can fuel infections, and oxidation. An opposite problem from iron deficiency is having too much iron. It's a delicate balance and best not to interfere with without a doctor directing and monitoring things.