PROBLEM TO BE SOLVED: To provide X-ray diagnostic compositions having ultra-low concentrations of iodine for X-ray examinations to improve patient safety, and further provide methods of X-ray examinations wherein a body is administered with an X-ray diagnostic composition and irradiated with a reduced radiation dose.SOLUTION: A composition comprises iodixanol or a compound of formula (II).SELECTED DRAWING: Figure 1【課題】X線検査及びその間における患者安全性の向上のための超低ヨウ素濃度を有するX線診断用組成物の提供。及び身体にX線診断用組成物を投与し、低減された放射線量を照射するX線検査方法。【解決手段】イオジキサノール又は式(II)で表される化合物を含有する組成物。【選択図】図1