Digital radiography is a form of x-ray imaging, where digital X-ray sensors are used instead of traditional photographic film. Advantages include time efficiency through bypassing chemical processing and the ability to digitally transfer and enhance images. Also less radiation can be used to produce an image of similar contrast to conventional radiography.

Digital Radiography (DR) or (DX) is essentially filmless X-ray image capture. In place of X-ray film, a digital image capture device is used to record the X-ray image and make it available as a digital file that can be presented for interpretation and saved as part of the patient’s medical record. The advantages of DR over film include immediate image preview and availability, a wider dynamic range which makes it more forgiving for over- and under-exposure as well as the ability to apply special image processing techniques that enhance overall display of the image. The largest motivator for healthcare facilities to adopt DR is its potential to reduce costs associated with processing, managing and storing films. Typically there are two variants of digital image capture devices.



Schick CDR

Schick CDR dental x-ray sensor

The radiological examinations in dentistry may be classified in:

  • intraoral where the film or the sensor is placed in the mouth, the purpose being to visualize a limited region.
  • extraoral where the film or the sensor is outside the mouth and the purpose is to visualize a wide region.

In dentistry, extraoral imaging splits in: Panoramic X-ray (aka "panorex" or "pano") showing a section, curved following more or less mandible shape, of the whole maxillo-facial block and the Cephalometric X-ray showing a projection, as parallel as possible, of the whole skull. A dental imaging (Kodak processor) [1] reader is used to upload the images onto a server or work station for reviewing, editing, or archiving the dental images.


One particular type of digital system uses a Memory Phosphor Plate (a.k.a. PSP—Photostimulable Phosphor) in place of the film. After X-ray exposure the plate (sheet) is placed in a special scanner where the latent formed image is retrieved point by point and digitized, using laser light scanning. The digitized images are stored and displayed on the computer screen. This method is halfway between old film-based technology and current direct digital imaging technology. It is similar to the film process because it involves the same image support handling but differs because the chemical development process is replaced by the scanning process. This is not much faster than film processing and the resolution and sensitivity performances are contested. However, it has the clear advantage to be able to fit within any pre-existing equipment without modification because it replaces just the existing film.

Also, sometimes the term "Digital X-rays" is used to designate the scanned film documents which are handled by further computer processing.

Other types of digital imaging technologies use electronic sensors. A majority of them first convert the X-rays into visible light (using a GdO2S or CsI layer), which is further captured using a CCD or a CMOS image sensor. Some of them use a hybrid arrangement which first converts the X-rays into electricity (using a CdTe layer) and then captures this electricity as an image with a reading section based on CMOS technology.


  1. [1] Eastman Kodak Company, "Introduction to Digital Radiography: The role of DR in Medical Imagaing', Rochester, NY, 2000


CR/DR Basics