Barium sulfate is a better choice than barium chloride for adding definition to X-rays because it is insoluble in water and therefore can be used as a contrast agent in X-ray procedures without dissolving in the body. Barium chloride, on the other hand, is soluble in water and can be absorbed by the body, which can be harmful.
The solubility of BaCl₂ in water at 26°C is 37.5 g/100 mL.