Digital Radiography

What is Radiography?

Radiography refers to the process of taking x-rays. The U.S. Food & Drug Administration (FDA) defines x-rays as: "radiation, waves or particles that travel through the air like light or radio signals. X-ray energy is high enough that some radiation passes through objects (such as internal organs, body tissues, and clothing) and onto x-ray detectors (such as film or a detector linked to a computer monitor). In general, objects that are more dense (such as bones and calcium deposits) absorb more of the radiation from the x-rays and don’t allow as much to pass through them. These objects leave a different image on the detector than less dense objects. Specially trained or experienced physicians can read these images to diagnose medical conditions or injuries."

What is Digital Radiography?

Simply put, a digital radiograph is an x-ray without film. Instead of traditional radiographic film, a reusable phosphorescent plate in an X-ray cassette is used. A digital image is created through a technique that produces images of objects by electronically detecting the arrival of x-ray photons transmitted through the object or emitted from it on various media and converting the sensed analog signals to digital signals representing the intensity of x-ray photons at each position. A digital radiography can be stored, diplayed and manipulated (to improve image quality) on a computer.

A Digital Radiography System is made up of several components:

  • Digital Image Receptor: a device that intercepts the x-ray beam after has passed through the patient's body and produces a digital image.
  • Digital Image Processing Unit: a system that allows the digital image to be processed after it is recorded. Digital processing enables us to change image characterisitics such as contrast, clarity, size, etc.
  • Image Management: performed by the computer system that controls the digital image process. The systems functions include controlling movement of the image through the digital radiography system's other components and associating the image with other data
    Image Courtesy of
    within the system.
  • Image and Data Storage Devices: Digital radiographs and other digital medical images are stored as digital data. There are several types of systems for storing the data. The most common are Digital Image Management Systems (DIMS) and Picture Archiving and Communication Systems (PACS)
  • Interface with Patient Information System: an adjunct to the digital radiography system that allows for the transfer of digital images to the patient information system which contains data such as Patient ID, scheduling, medical history, etc.
  • Communications Network: A network available for transferring digital images that is made up of a variety of integrated systems. This network makes it possible for digital images to be easily and rapidly transferred from one location to another, such as within the imaging facility to storage and display devices, to other healthcare provider's locations, or to an individual's insurance carrier.
  • Display Device with User Display Controls: A digital display device is an image display for digital images. In some instances a standard computer monitor with high resolution can be used. The user display controls allow the viewer to perform functions such as zoom, reverse, or imagae comparisons.It also enables the viewer to adjust and optimize image characteristics, such as contrast, to improve image readability.

Types of Digital Radiography

  • Direct Radiography (DR): a process for capturing radiographic images that uses a cassette with a electronic cable attached to it instead of having film inside it. The digital cassette captures and stores the x-ray. It is then developed by an DR image processor that produces the digital image.
  • Computed Radiography (CR): uses very similar equipment to conventional radiography except that instead of film to create the image, an imaging plate is used. The imaging plate is run through a computer scanner to read and digitize the image. The image can then be viewed and enhanced using software that has functions very similar to conventional image-processing software, such as contrast, brightness, and zoom.
  • Charged-Coupled Device (CCD): a light-sensitive integrated circuit that stores and displays the data for an image in such a way that each pixel in the image is converted into an electical charge the intensity of which is related to a color in the color spectrum.


  • Faster processing time
  • Lower patient radiation exposure
  • Ability to duplicate & copy images without loss of image quality
  • Requires less physical storage space
  • Rapid image retireval and transfer
  • No need for costly and potentially harmful developing chemicals


  • Possible interoperability issues with existing systems
  • High initial investment cost
  • Lack of universal use
  • Potential for fraudulent use (see article)

Image Quality Comparisons

The images below show the difference in clarity and readability between a digital image (left) and a traditional x-ray (right).

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Image Courtesy of: //

Uses of Digital Radiography

In Veterinary Medicine

Roughly a decade after being introduced to veterinary medicine, digital radiography has established itself in the field, with somewhere between one-half and twothirds of companion animal practices having converted from film to digital, according to industry estimates. Digital radiography hits tipping points By Brian Hutchins For Veterinary Practice News “Most larger practices already have digital, and thus new sales come from small practices,” says William Hornof, DVM, MS, Dipl. ACVR, chief medical officer for Sound-Eklin of Carlsbad, Calif., a unit of VCA Antech. “Continued growth will come from upgrades, replacement of inferior systems, service, and cloud services.”
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Digital radiography, which eliminates the darkroom, chemicals and manually filed plastic film, moseyed into veterinary medicine in the early 2000s, hit its stride around 2004, and today is galloping full-tilt into mainstream use.

“The technology has gotten better, the software has gotten better and the prices on the client side have gotten better,” said Seth Wallack, DVM, Dipl. ACVR, who practices in San Diego. “The time of the early-adopter of digital is over, and now it’s more mainstream. It’s becoming the norm.”
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Related Terms

Picture Archiving
Digital Image Management System (DIMS)
Picture Archiving and Communications System (PACS)
Dental radiography
Digital Imaging and Communnications (DICOM)


Got Film? Digital X-ray Machines Don't Need It by Victoria Reitz
How It Works by Teresa Duncan, M.S.
Why switch to digital radiography by Gordon J. Christensen, D.D.S., M.S.D., PhD.