ABSTRACT
A medical image is produced for some speciœc diagnostic purpose, and the most meaningful measure of its quality is how well it fulœlls that purpose (Barrett 1990). ™e usefulness of an image can, however, be determined at di›erent levels (Wagner 2007), from its pure technical properties to its impact on society (see Table 13.1). Depending on the point of view, each of these levels could be valid, but in the context of this chapter, we leave aside the technical parameters of level 1 such as contrast, resolution, noise, DQE, NEQ and we focus on level 2, which is where medical physicists’ and radiologists’ e›orts meet. At this level, we are interested in quantifying how the information available in the image can be e–ciently used by the radiologist for making a correct diagnostic decision.
