What is risk perception in general and in radiation protection?

In view of the universal roll Risk Perception plays in our daily life, the author makes an effort to understand this notion better. For such a subtle task, it will be good to know something about the person, who undertakes such a challenge. Thus, he first makes a short description of himself in a number of relevant personal feature, emphasising rather what he is not: cadre of insurance company.... etc. He starts with a literal understanding of the idiom Risk Perception in English and in other languages (in Chinese). This formulation, still abstract, is framed with concrete objects, and materialised into touchable structures. He then puts life into these structures, and makes them accessible to emotion and experience. Now that this notion is animated, he follows it's way into life in the field of Radiation Protection, and find among others that the term Cost and Benefit correspond to the Chinese idiom, and that the system of Justification and Optimisation is as difficult to achieve objectively as an Upright Walk on the Confucian Path to-ward the Middle. One of the difficulties lies in the difference in the scale in estimating values. For instance, though the idea of Asian and Western Values are rather diffuse, their difference is never-the-less high enough to render it to be insurmountable, at least at present. These observation belong actually to common experience of Health physicists, and nothing new or spectacular is presented. The author emphasises only, again not a new idea of his own, only putting weight to, that perception depends on point of view, or rather on stand of viewing points, and rarely represent the whole story, the true situation. This leads, according to the author, to the well known and accepted term of Risk Residuum, in German, Rest Risiko. Despite of partialness of all perceptions, solid decisions are based on perception. We all know mournful consequences of unsound decision in our daily life. It is tragic, when this happens in history. The author knows also no King's Road to reasonably good perception to enable sound decision. Several points he himself thinks to have been of help to him, are sketched. (author)