Cassette-based computed radiography (CR) systems have continued to evolve in parallel with integrated, instant readout digital radiography (DR) systems. The image quality of present day CR systems is approaching its theoretical limits but is significantly inferior to DR. Further improvements in CR image quality require improved concepts. The aim of this review is to identify the fundamental limitations in CR performance. This will provide a background for the development of new approaches to improve photostimulable phosphor CR systems. It will also guide research in designing better CR systems to possibly compete with DR systems in terms of image quality parameters such as detective quantum efficiency and yet maintain CR convenience in being portable and more economical.