Just on the Iodine thing I noticed some comments regarding Iodine allergies, I do not believe there is such a thing technically, as it would very quickly result in death, there is Iodine toxicity which everyone is susceptable to although sensitivity may vary and this seems to be the issue with CT scans, what most people refer to as Iodine allergy is an immune response to specific proteins found in shellfish, one of these being from the Keyhole Limpet which is used in many vaccines and raises the question of Vaccines & Allergies, but that is another story.
I found this little statement regarding the CT reaction below:
.IV Contrast Dye. This reaction is non-allergic but can result in anaphylaxis because the high concentration of the dye causes mast cells to release their contents, which mimics an allergic reaction. While there is no test available for reactions to IV contrast, most patients can take the dye safely by taking oral steroids and anti-histamines hours before the contrast is given. The contrast is usually given in a less concentrated form to these patients. Let your doctor know if you’ve had a past reaction to IV contrast before receiving it again.