The Patient Scheduled for a CT Scan with Contrast Medium

The patient scheduled for a CT scan with contrast medium questions the nurse why the technologist asked her if she had any food allergies.Which response by the nurse is correct?

A) "The dye used for a CT scan is egg based, so egg allergies would prevent you from having the test."
B) "People who are allergic to dairy products are likely to be allergic to CT scan dye."
C) "Allergies to shellfish can be a problem because shellfish and CT scan dye are iodine based."
D) "Wheat is the preservative used in CT scan dye, so allergies to wheat may cause allergies to the dye."