The threat of a terrorist attack using a "Dirty Bomb" radiological dispersal device or even a small nuclear device is real. Researchers, industry and security planners are racing to develop and deploy a credible defense against this threat. Because, even though radiation detection technology and products exist today, and have existed for several decades, their performance falls far short of the kind of products needed to provide real cost-effective protection. This report reviews existing and evolving nuclear/radiological detection portals and technologies and provides reasoned, detailed and understandable analysis and recommendation on how to bring about the necessary technologies and how to make them efficient and cost-effective.