Dental Digital Radiography explained for better understanding and how it compares to regular analog radiographs.

1. Dental Digital
Radiography
DENTAL DIGITAL RADIOGRAPHY UNDERSTANDING IN A
FEW EASY STEPS. DENTAL DIGITAL IMAGES TODAY PROVIDE
ENHANCED RADIATION SAFETY LEVELS AND IMPROVED
DIAGNOSTIC PERFORMANCE. IT ALSO FACILITATES MORE
CHAIRSIDE TIME TO DEVOTE IN CARE OF DENTAL PATIENTS.

2. Basic Descriptive Terminology
Radiograph/Dental Image Versus X-rays
 A radiograph is a 2-dimensional view film of a 3-dimentional object
 With digital radiography (imaging) no film is utilized so the term
radiograph is not pertinent.
 In digital imaging the term Digital Image is used instead of
radiograph and refers to an image composed of pixels. Regular
radiographic films received its image density from the silver salts
exposure to the x-ray beam and required chemical processing to
view on the film.
 Dental Image is now used to describe what is viewed on
radiographs and/or digital images.
 A dental image appears radiolucent (dark or black) where the
tissues are thin or very soft and radiopaque (white or light) were
tissues are hard or dense like bone for example.

3. Advantages of Digital Imaging
 Superior gray scale resolution. Digital
imaging uses up to 256 or more
shades of gray. This advantage is
critical because diagnosis is often
based on contrast discrimination.
 Lower Cost and Effective Patient
Education Tool.
 Reduced exposure to radiation. Its
about 50 to 90% less than that
required for E-speed film used in
conventional radiography.
 Increased speed image viewing.
Image could be viewed within
moments after exposure.
 Increased Efficiency. More time
available chairside with treatments
and dental patient care
 Enhancement of diagnostic image.
 Conventional dental film only has 16
to 25 shades of gray. It has less ability
in capturing great detail or
resolution.
 Film not as sensitive to energy beam
x-ray.
 Exposed film had to undergo costly
and later environmental impact
chemical processing.
 Dentist, Assistant and Patient had to
wait for dental film processing.
Dental films had to be copied and
mailed to insurance companies.

4. Disadvantages of Digital Imaging
 Initial set-up and training to include regular maintenance and repair
On the up side it does away with darkroom machines, chemicals and
disposal.
 Image quality. Human eye can only perceive 8 to 10 lp/mm so
debate since regular film radiographs are higher 12 to 20 lp/mm.
CCD allows 10 Lp/mm so more closer to what is needed to detect
disease. Lp/mm= ability of computer to capture detail of images.
 Sensor Size and thickness
 Infection control
 Legal Issues. Always keep non-enhanced originals saved on
computer prior to digital image enhanced for discovery
 Infection Control
 Wear and Tear

5. Digital Subtraction
A benefit of using Dental Digital Radiography is the enhancements that the software
allows for diagnostic purposes
Digital Image
Radiopaque (white areas) with
outer area radiolucent (black or
dark gray)
Digital Image
Bite-wing Image
Radiopaque (white areas) as first
image and as normal image view
Bite-wing Image
Digital Subtraction
Bite-Wing Image
This digital image has the Digital Subtraction
enhancement done after image stored on the
computer software. It reverses the shades of gray for
diagnostic purposes. Radiopaque (normally white
images are now looking translucent (dark or gray)

6. Review of Basic Terminology for Easier Understanding
 Analog image- Image produced by conventional film
 Bit-depth image- number of possible gray- scale combinations for each pixel. (e.g., 8 bit-depth
image has a gray scale combination of 2 (8) power, which equals 256 shades of gray.
 Charged- Coupled device- (CCD) – CCD is an image receptor found in the intraoral sensor.
This solid state detector is used in a fax machines, home video cameras and now in digital imaging.
 Digital Imaging- a method of capturing a radiographic image with a sensor which gets broken
down into electronic pieces to later store and present the image in a computer.
 Digital image- An image composed of pixels.
 Digital Subtraction- This is a special feature in digital imaging when one reverses the gray scale
as an image is viewed, for example, radiolucent images that in the digital image look black will
appear white or radiopaque and the areas normally radiopaque (that normally appear white such as
gold crowns or fillings will look translucent or radiolucent.

7. Review of Basic Terminology Part two
 Digitize- to convert an image into a digital form.
 Direct Digital Imaging- Method of obtaining a digital image in which an intraoral (inside of the
mouth) sensor is exposed to x-radiation to capture an image that can be viewed on the computer
screen.
 Indirect digital imaging- is when we obtain an image that was scanned from an existing film. It
is converted into digital form by using a CCD camera. (CCD is an image receptor) It is considered a
copy since not the original for was scanned. It’s important to always save original film and digital
images for legal purposes and insurance in case of denial on a claim.
 Line Pairs/Millimeter (lp/m)- Measurement used to evaluate the ability of the computer to
capture the resolution (or detail) of a radiographic image.
 Pixel- unit of information in digital images and these discrete units of information
are also termed picture elements.
 Sensor- for digital imaging this is a small detector that is placed intraoral (inside of
the mouth) to capture a radiographic image

8. Another important term is
Storage Phosphor Imaging-
when a digital image is
obtained by recording it on
phosphor- coated plates and
then placed into an electronic
processor where a laser scans
the image in the plate and
produces it into a the computer
screen. A scan is a copy of the
stored original image. One
could imagine storing Austin
Powers (Mike Myers) Dental
image to computer to later
show him on monitor. (Image
Virgin Media, 1990).

9. Understanding Digital Imaging in Easy Steps
How does it really work and to what purpose?
 Digital imaging main purpose is to generate images that can be
used for diagnosis and assessment of dental disease. Also
equivalent to conventional film yet more time efficient, economic
and with more informational data for diagnostics.

10. How does Digital Imaging Really Work?
1- Dental Imaging works by capturing an image using a sensor that
“breaks” the image into electronic pieces or picture elements known
as pixels and presenting and storing the image using a computer.
 In contrast, film based images are produced when the x-ray
photons strike the intraoral film and that information was recorded
in the film silver halide crystals latent until we developed the image
with processing chemicals. The image taken on film is known as an
analog image. Analog images are composed of shades of gray
that flow into each other like a cloud of grays.
 Digital imaging creates pixels with discrete gray values for each
pixel forming a distinct mosaic pattern. This provides a lot more
detail and important in dental radiography when we wish to detect
disease. In analog image its harder to detect for example a minor
radiolucent cyst at the apex of a tooth for has more foggy shades
of gray.

11. Digital Fundamentals
2- As in conventional radiography, an x-ray beam source is needed
and in digital imaging we have it strike the sensor using beam
alignment devices. This is called Direct Imaging since we place an
intraoral sensor to capture directly the image to them transmit to a
computer. In indirect imaging, a scan and therefore a copy of a
traditional radiograph is done using a CCD camera that digitizes
the image to display on computer. A second indirect system is the
Photo-Stimulate Phosphor Imaging. (PSP)-On Next slide discussed.
 The sensor may be wired with a fiber optic cable placed within
the alignment device or work wireless transmitting electronically
the image.
 The data acquired by the sensor is communicated to the
computer in analog form and then converted into digital form
by an analog to digital converter. Software is then used to store
the image electronically. The image is displayed quickly and
ready to be enhanced for interpretation or diagnosis.
 With digital imaging the term Image is used (not x-ray or
radiograph)

12. Two Indirect Digital Imaging Systems
Scanning Traditional
Films
 Use of a CCD
Camera and a
computer
 Considered a copy
of an original image
Storage Phosphor
Imaging/
 A reusable plate
coated with
phosphors is used
instead of a sensor
 Its is flexible and
inserted in mouth.
The plate in then
placed in an
electronic
processor where a
laser scans it
producing image
to view on
computer.

13. The second type of
indirect imaging is
the Storage Phosphor
Imaging
This system uses a reusable imaging
plate coated with phosphors acting
as the sensor and is wireless for has
no cable. The images are cleared
when exposed to a view box after
several minutes. Once the images
are erased the phosphor plate may
be wrapped in plastic and sterilized.
Description of image on the right:
GENDEX DENOPTIX I/O PA USB
DENTAL DIGITAL PHOSPHOR PLATE
IMAGING X-RAY SCANNER SYSTEM
(2011 converted to USB) A laser scans
the plate and it takes 30 sec. to 5 min

14. Sensor with Beam alignment
Device
Factoids about Sensors
 A pixel in the sensor acts like a
well that receives electronic
photons from x-ray machine.
There it reacts with electrons
embedded in the circuit of silicon
chip . The pixel plays the role of
the silver crystals in a film.
 The advantage is that the pixel
has a more structured ordered
arrangement. (more detail)
 The x-radiation after activating
the electronic charges in the pixel
“well” causes an electronic latent
image to be produced then is
transmitted and stored in the
computer and converted to a
visible image on the screen.

15. You are now more Confident about
understanding Dental Digital Radiography
 Dental Assisting is a rewarding
field
 It is important to be familiar
with different techniques,
dental office materials and
technologies.
 With pre- text book reading,
understanding of lectures and
actual practice you will be on
your way to becoming an
excellent Assistant
 A summary handout is
available

16. References
Joen M. Lannuci, Laura J. Howerton. (2012). Dental
Radiography: Principles and Techniques. US: Elsevier
Intellitec Institute
By Theresa Nielsen for Intellitec Dental Assisting 2014