The concern in radiation safety is growing rapidly among our society as nuclear energy and radiation application are more widespread nowadays. Radiation is everywhere and we cannot stay alone with it. After the nuclear disaster in ‘Japan 311 earthquake’ some years ago, people are more concerned to radiation. However, the most important is to learn about how radiation makes changes in our daily life. The population fears to radiation because they know nothing about it. Although high radiation dose will harm human, low radiation can hardly cause any problem immediately to our body. If we can use radiation properly, we can benefit in many aspect such as medicine, industry, electric power, etc.