What Can X-rays and Ct scans really tell us?

Ok, so I phrased this as a question because I really wonder sometimes--my pulmonologist was going over my last CT which showed that the "possible early infiltrates" in my right UPPER lobe from earlier scan (described as possible pneumonia but never treated) were no longer seen. Now, I'd had a prior x-ray in between the two scans when I had gone to the clinic for SOB and slight fever. Infiltrates in the right LOWER lobe were found, and I was treated for pneumonia. Growing ever suspicious and less confident with my medical care so far, I get a little alarmed when I see these discrepancies, so I told him about the x-ray and asked him what the deal was with that? He pointed out, since X-rays are basically a flattened image compared to a CT scan,some objects that appear in a chest x-ray are not always where they truly are. Even though that seems glaringly obvious now, my head is still truly spinning. So...why don't the techs just stand us on our heads and take the shot?