The need for fasting in X-ray examinations is closely related to the type of examination, and the details are as follows: 1. X-ray general examination: for X-ray examinations of the chest, bone and joint, and spine, patients can eat normally and do not need to fast; 2. X-ray contrast examination: except for barium meal of the esophagus, barium meal of the upper gastrointestinal tract, barium meal of the whole gastrointestinal tract and barium enema require patients to fast on the day of the examination; intravenous pyelography requires fasting on the day of the examination to prevent vomiting when the contrast agent is injected, which may lead to accidental aspiration.