Final answer:
The primary concern for patients facing CT scans is the anxiety related to the confined space of the CT tube, although exposure to x-rays is also a significant concern.
Step-by-step explanation:
The most frequent concern of patients scheduled for CT studies is anxiety about entering the confined space of the tube (option b). This anxiety stems from the need to be enclosed in a tube-like device, sometimes for as long as thirty minutes, which can cause discomfort and feelings of claustrophobia. In comparison, exposure to x-rays (option a) is a concern as well, but the level of anxiety specifically about the space tends to be a more immediate worry. The potential for iodine allergies (option c) and magnetic pull on metal objects (option d) are pertinent to other imaging modalities such as MRI, which uses powerful magnets, not CT scans. When considering the drawbacks of CT scans, it is the x-rays usage that raises concerns for potential long-term effects like cancer, not the immediate experience inside the scanner.