Dental radiology is the cornerstone of quality veterinary dentistry. It is impossible to provide quality veterinary dental
care in lieu of this invaluable diagnostic modality. Treatment decisions rely on the visualization of subgingival pathology
that only radiology can feasibly provide. Digital dental radiology has proven to be a reliable and affordable choice for veterinary
practices that are committed to practicing quality veterinary dentistry. The following discussion is a continuation of a series
of articles on radiography and will provide an overview of choices concerning this exciting diagnostic tool.
Direct digital radiography
Direct digital radiology uses a digital sensor instead of film to capture the images. Standard radiography units (generators),
discussed in a prior article in this series, come wall-mounted, as mobile floor models or most recently hand-held. When these
units are activated to take an image using a digital sensor, the photons generated create a flow of electrons within the digital
sensor. The image is simultaneously transferred to the computer either by a USB cable or most recently wirelessly using Bluetooth
technology. The computer then processes the gray-scale data, arranging pixels based on the photon passage through the various
oral-cavity tissue densities to create the image. This entire process takes only seconds to complete before the image appears
on the computer screen.
Indirect digital radiography
Indirect digital radiology uses photon energy emitted from the generator to emit light from a phosphor plate rather than a
digital sensor. The plate is then placed in a scanner. The light emitted is scanned by a laser and transmitted to the computer
software for image generation using the gray-scale data one pixel at a time as described with direct digital radiography.
Direct vs. indirect comparison
Resolution varies among systems, however image quality is reliably constant and diagnostic images are easily obtainable with
any digital system.
Speed is a tremendous advantage for direct digital over both film and indirect digital dental radiology. Images are generally
present on screen in less than 6 seconds with this modality. Processing times vary with indirect digital depending on the
resolution desired, however times are similar to hand developing.
Sensor size is a big advantage of indirect digital systems. A size 4 indirect phosphor plate is noticeably larger that the
size 2 sensor limitation of direct digital. This makes image capture easier (due to a larger target) and quicker in that a
larger area can be imaged decreasing the number of images required. Size 4 sensors are particularly convenient when taking
a full-mouth series on a large dog or when screening for nasal pathology.
Digital decreases exposure requirements. Depending on the sensor, dramatic reduction techniques can be accomplished. Archiving
is a tremendous advantage of digital, too. Although individual digital pictures can be taken of radiographs acquired using
film, this practice is time-consuming, and archiving within practice-management software remains a manual process. Because
of the speed direct digital provides, the image can be viewed within seconds on the screen and adjustments can be made to
the tube head with the film still in place if the positioning is incorrect.
When taking a full-mouth series with indirect digital and film, it is customary to expose the entire series of images. Excessive
anesthetic time precludes development of each individual film or phosphor plate before moving on to the next image. Damage
to film carries little cost concern, but damage to a digital sensor may result in a very expensive replacement. Warranties
generally do not cover trauma to the sensor. Keep in mind that allowing a patient to bite the sensor could cost thousands
of dollars for a replacement. Phosphor plates also can be damaged, but replacement costs are minimal by comparison ($25-$90).
Finally, images may be manipulated within the software to enhance visualization of structures. Adjustments may be made to
brightness and contrast, minimizing retakes. Images may be colorized, visualized in 3D, optimized and measured. These manipulations
only can be done effectively with digital images.
Each individual should evaluate multiple systems to compare cost, ease of use, compatibility with practice-management software
and technical-support options. Use of digital technology will afford today's progressive practitioner the diagnostic modality
needed to practice quality veterinary dentistry, greatly enhancing patient care.
Brett Beckman, DVM, FAVD, Dipl. AVDC practices referral dentistry at Affiliated Veterinary Specialists, Orlando, Fla.; Noah's
Animal Hospitals in Indianapolis; and at Florida Veterinary Dentistry and Oral Surgery in Punta Gorda, Fla. He is president-elect
of the American Veterinary Dental Society and diplomate of the American Academy of Pain Management.