Whether or not an appointment is required for a CT in the hospital is determined by the part of the exam and the patient’s requirements. If the patient is having a simple plain CT exam, an appointment is generally not required and the patient can come directly to the exam window to check in and line up for the exam. If the patient is having an enhanced CT exam, an appointment is required because another purpose of the appointment is to take a detailed history of the patient’s medical and allergy history. If the patient is severely hyperthyroid or allergic to iodine contrast agent, such patients are not allowed to have an enhanced CT exam. Some patients, such as those taking metformin medication, need to stop taking the medication for 48 hours before they can have an enhanced CT. so patients who are having enhanced and vascular type exams need to make an appointment.