Advances in Digital Radiography: Physical Principles and System Overview

Abstract

During the past two decades, digital radiography has supplanted screen-film radiography in many radiology departments. Today, manufacturers provide a variety of digital imaging solutions based on various detector and readout technologies. Digital detectors allow implementation of a fully digital picture archiving and communication system, in which images are stored digitally and are available anytime. Image distribution in hospitals can now be achieved electronically by means of web-based technology with no risk of losing images. Other advantages of digital radiography include higher patient throughput, increased dose efficiency, and the greater dynamic range of digital detectors with possible reduction of radiation exposure to the patient. The future of radiography will be digital, and it behooves radiologists to be familiar with the technical principles, image quality criteria, and radiation exposure issues associated with the various digital radiography systems that are currently available.

Digital radiography detectors – A technical overview: Part 1

“…These digital systems are traditionally split into two broadly defined categories: computed radiography (CR) and digital radiography (DR). 4,5 Although this taxonomy is commonly accepted other classifications are described: direct digital radiography and Indirect Digital Radiography technologies (including CR). 6 In this case, the detector classification is related with the conversion process of X-ray energy to electric charge.…”

“…Despite charge-couple devices (CCDs) could be considered indirect conversion DR systems, they are not flat-panel detectors and studies dealing with CCD-based digital general radiography are rare. 5 This technology is mainly related to other applications such as mammography and digital dental radiography. 5 For this reason CCDs will be excluded from this review.…”

“…These systems can be further divided into direct and indirect conversion groups depending on the type of X-ray conversion used. 5 Table 1 shows the differences among detector technology concerning three components of digital detectors 7 : the capture element, the coupling element, and the charge readout element.…”

“…11 The phosphor crystals are usually cast into plates into resin material in an unstructured way (unstructured scintillators). 5 When the SPS is exposed to the X-ray the incident radiation excites electrons from the valence band to the conduction band ( Fig. 2a and b).…”

Digital radiography detectors – A technical overview: Part 2

“…5 This technology is mainly related to other applications such as mammography and digital dental radiography. 5 For this reason CCDs will be excluded from this review.…”