Cardiac CT is used to look at the specifics of the coronary arteries of the heart. A cardiac CT usually refers to a CT of the coronary arteries of the heart, called a CTA. is usually used to look at the specifics of the coronary arteries of the heart. Before a cardiac CTA, an intravenous contrast agent, such as iohexol, is injected. By looking at the condition of the coronary arteries under the CT images, such as the presence of stenosis, the presence of developmental variations or abnormalities in the origin of the coronary arteries, and the degree of coronary artery stenosis, it helps to guide clinical treatment. Patients should not drink caffeinated beverages for 12 hours prior to the examination, should not eat solid food for 4 hours, should be encouraged to drink water, and should not do any exercise. Remove metal objects before the examination and lie supine on the examination bed in a relaxed and comfortable position. Repeat the breath-holding exercise, ensuring that the chest and abdomen are at rest during the exposure, and observe the change in heart rate during the breath-hold, which should be less than 10%. Consultation with a specialist is recommended for the specific need for cardiac CT and interpretation of the results.