CR and DR triumph over conventional techniques (2)

             CR was the first digital radiographic technique to be introduced. Systems are based on an
imaging plate that is similar to the amplifier screen of a conventional radiography unit. The
difference is that this storage phosphor imaging plate retains information from incident
photons as a latent image. This image can then be retrieved following stimulation by a readout
laser.
             The first CR systems required more dose than screen-film systems to achieve a similar clinical
performance. But these systems did allow the radiation dose to be varied. This meant that the
dose could be reduced substantially in situations where reduced image quality was acceptable.
             Continuous improvements to the detector material and readout technology have led to substantial
gains in dose efficiency and enhanced spatial resolution. Innovations include dual readout
technology and needle-crystalline detectors. The dose efficiency of CR systems is now
approaching that of DR (mobile x ray machine) systems.