X 线造影剂有哪些?其发展情况如何?碘卡明和其它造影剂有何不同?用前要作过敏试验吗?其临床价值如何?答:造影剂按它和人体组织密度的比较来区分,一般可分为两大类:一类是其原子组成比人体组织密度高,在 X 线下显黑影的,叫阳性造影剂,主要是钡和碘这两大类化合物;另一类是组成比人体组织密度低的,在 X 线下显白影的,叫阴性造影剂,这类主要 What is the development of X-ray contrast agent? What is the difference between iodine and other contrast agents? Is there any allergy test before use? What is the clinical value? A: Contrast agent is distinguished from the contrast of human tissue density, Generally can be divided into two categories: one is the atomic composition than the high density of human tissue, X-ray was dark shadow, called positive contrast agent, mainly barium and iodine two categories of compounds; the other is the composition Lower than the density of human tissue, the white shadow in the X-ray, called negative contrast agent, such as the main