What is the contrast agent commonly used in CT scans?

The commonly used contrast agent in CT scans is iodine-based contrast agents. These agents are preferred because they are highly effective at enhancing the visibility of vascular structures and various organs within the body. Iodine's atomic number is high, which provides excellent contrast on the images produced during a CT scan, allowing for clearer and more detailed visualization of tissues and blood vessels.

Iodine-based agents work by absorbing X-rays more effectively than surrounding tissues, thereby highlighting areas of interest. This is particularly useful in diagnosing conditions such as tumors, blood clots, and other abnormalities. The rapid distribution of iodine-based contrast within the bloodstream also facilitates real-time imaging of organs and vessels.

Other options, while used in specific imaging contexts, do not serve the same purpose in CT scans as iodine-based agents do. For instance, carbon dioxide is sometimes used as a contrast agent in specific vascular procedures due to its low viscosity and safety profile, but it is not standard for general CT imaging. Barium sulfate is primarily used for gastrointestinal studies, while gadolinium is the contrast agent of choice for MRI scans rather than CT. Thus, iodine-based contrast agents remain the standard for CT imaging due to their effectiveness and versatility.