Dale A. Miles BA, DDS,
inevitable shift towards digital x-ray
imaging continues. In the June 2002
issue of Dental Products Report (DPR),
Gail Weisman reports that digital
radiography "is being used by 14%
of current respondents". What does
that mean? DPR has conducted surveys
of dentists in the US by sending 2000
questionnaires randomly to dental
offices. In 1999, only 8% of those
responding said they'd adopted digital
x-ray systems. The same survey sent
recently yielded the 14% figure. The
response rate for these questionnaires,
however, was about 12.2%. While this
number is small, there seems to be
a trend. More of us are adopting digital
technology, even digital x-ray systems.
is Good!" Adopt and Adapt
dentist you must adopt new technology
all the time. Then you have to adapt
the technology to your office and
practice philosophy, and you have
to adapt to the technology yourself.
You cannot learn new techniques vicariously.
Ours is a "hands-on" profession. Digital
radiology or digital imaging is no
exception. The good news is that it's
not as hard as you think. I've said
it before. I'll say it again. The
only real change or "paradigm shift"
when adopting digital imaging is electronic
image processing (EIP).1,2 Dentists
can now perform simple image altering
tasks to see disease features better.
This will help us make better diagnoses
and better treatment decisions. Medical
radiologists have been doing this
for 10-20 years with CT (computed
tomography) and MR (magnetic resonance)
images. Every image captured digitally
in these imaging modalities is altered
form the original. Chest images, breast
images, neurologic images --they're
all subjected to EIP on the working
monitor so that the clinician can
detect lung nodules, breast calcifications
and small density differences between
similar gray matter and lesions in
the brain. This is the rule, NOT the
exception. We want to process the
image electronically to detect disease
better (figure 1). If we want to move
forward with our medical colleagues,
instead of falling further behind,
we have no choice but to adopt the
new digital imaging systems. The most
frustrating thing for a dentist is
to try to practice new dentistry with
old tools. Adopt and adapt, you have
Panoramic radiograph taken of a patient
with a "mixed" dentition. The radiograph
Same radiograph as in 1a but scanned
in a desk top scanner and processed
with an "equalization" filter in PhotoshopTM
3.0. This simple EIP step has effectively
recovered information in an otherwise
would you want to change?
all of the advantages of digital imaging
listed in Table 1 below, there are
other reasons to change to digital
x-ray imaging systems. If you are
considering retiring in the next 5
years, you'd like to make your practice
as attractive as possible to the buyer;
the more contemporary your office
equipment, the more attractive the
practice. And, if you're contemplating
hiring a new associate, digital imaging
systems show that you are practicing
"high-tech" dentistry. Similarly,
your patient's perception of how "up-to-date"
you are as a dentist is enhanced by
digital x-ray systems with their instant
image display and their reduced x-ray
dose. If you are a recent graduate
setting up a practice, or a clinician
moving to a new office, there are
reduced initial and on-going costs
associated with digital systems. The
annual savings in "tech time" alone
can be enough to pay for the system.3
It is true that doctors have experienced
problems with solid-state sensors,
but in most cases the company has
replaced the system according to the
users I talk to constantly at dental
meetings. But, with sensors there
are no chemical costs, film costs
or hazardous materials handling costs.
Film mounts are gone too. These materials
and services are eliminated and thus
reduce your supply costs. If you must
have a "hard copy", photographic quality
paper can be used for your x-ray images.
And, this paper can be used to archive
your clinical photographic images
as well. If you are concerned that
the paper image will deteriorate with
time, don't be. The archived digital
image on your hard drive, CDROM or
DVDROM will last longer than your
practice! You can always print a new,
1 contains a list of the positive
attributes* of digital imaging systems.
2. Less x - ray dose
3. Better disease detection
4. Better quality control of images
5. Improved patient education
6. Ease of attachment to electronic
7. Faster reimbursement for electronic
claims requiring images
8. Less environmental impact on
the local community
9. Elimination of darkroom processing
10. Elimination of the darkroom
11. Improved archival quality
12. Less cabinet space required
13. Better integration with electronic
* each of these "attribute" has
been discussed in previous articles
as an "advantage"
what's wrong with film?
as an image receptor for dental imaging/interpretation
tasks is excellent. I have never said
that it wasn't. But, since it is at
once the receptor, the display and
the archiving media, it does have
some significant drawbacks.
We've all tried to "read" x-ray films
that were a little too light or a
little too dark in our practices.
Even in the best dental practices,
quality control of the solutions in
our processors "breaks down". This
is not the case with digital images.
Their density and contrast is much
more reproducible. And, if the image
is a little light or dark, no re-exposure
of the patient is necessary. You simply
perform EIP on the image to optimize
the image characteristics .
A #2 dental film as a display "mechanism"
is also suspect. The image is small.
Dentists rarely use darkened environments
to view these films. And, in most
offices, dentists do not magnify the
image to help them view the potential
disease changes. By using a computer
monitor, dentists automatically use
image intensification (II) inherent
in the system. This II process optimizes
the image for the poor viewing conditions
(ambient light from windows, fluorescent
light, etc…) in which most practitioners
interpret the radiographic findings.
In addition, all monitor x-ray images
are magnified when viewing. Patients
can finally see changes on the image
when they're viewing the computer
screen. It's like watching television
for them, an activity they are all
familiar with. You don't have to invite
them out of the chair to try to show
them the tiniest black "dot" on the
distal of that second premolar, only
have them to remark "Boy, Doc, you
sure got good eyes. I don't know how
you can see those things!"
Finally, film as an archival device
cannot compare to binary data; that
is, a digital image stored on a hard
drive or other storage media such
as a CDROM. We all have yellow or
brown films in our cabinets from poor
fixation by chemical image processing.
I know I have been embarrassed pulling
such images out of a chart I haven't
seen in months to show the patient.
This does not happen with digital
images. The image you "save to disk"
will keep its image fidelity forever.
You can print a "hard copy" of this
data anytime you want and it will
look the same as the day you stored
it. Digital images have lots of advantages,
some of which we don't have to think
Eastman Kodak has announced that they
will no longer manufacture Ektaspeed
PlusTM film after December 2001. They
have introduced an even faster film,
InsightTM (an F-speed film) to replace
Ektaspeed. In fact, because of the
rapid acceptance of InsightTM film
by dentists using D-speed (UltraspeedTM)
film, Kodak will probably abandon
D-speed film production in the near
future. Furthermore, Eastman Kodak
is examining the need to introduce
even more "digital" dental products,
like their DMI 1200TM inkjet printer
and their DC290TM still camera to
our profession. They do, after all,
make both CCD (charge-coupled device)
and CMOS (complementary metal oxide
semiconductor) devices for many other
camera and video camera manufacturers.
If the premiere dental imaging company
in North America is "going digital",
how long can we survive with our film-based
are the current digital x-ray "players"?
this list changes constantly! But
why is that? In large part, it is
because of our profession's reticence
to move forward in a digital world.
According to Arthur C. Clarke, new
ideas pass through 3 periods.
1. "It can't be done.
2. It probably can be done, but it's
not worth doing.
3. I knew it was a good idea all along"!
the same be said for digital x-ray
imaging. I might take a little "poetic
license" with this concept with regard
to dentists adopting digital sensor
systems. I would say it will go something
1. I don't need digital x-rays.
2. I see the advantages, but I'll
stick with film.
3. God, I wonder how I ever practiced
4. My staff would mutiny if I ever
went back to film!
2 lists the current "solid-state"
sensor vendors (direct digital capture
systems) and their products.
Table 3 lists the companies offering
storage phosphor or reusable storage
phosphor (PSP) systems (indirect digital
Direct Digital Sensor Systems
||USB 1 and 2
||PCI and USB
*all of these sensor
systems have high spatial resolution
capability - from 8-22 lp/mm.
** cost is for "basic system", some
manufacturers have additional costs
for "capture system", software, and/or
3 below lists the manufacturers of
photostimulable (reusable) phosphor
systems. These should be thought of
as indirect digital systems since
the receptor is exposed to x rays
and then processed, by scanning with
a laser beam to release the light
energy stored, to create an image
from the electronic signal. Unlike
CCD or CMOS detectors, the phosphor-based
imaging systems are 2-step systems
like film, requiring similar infection
control steps and handling. They also
need to be "discharged" by flooding
their surface with high intensity
light, like that from a viewbox, for
several minutes before reuse. Failure
to discharge the previous image completely,
may result in a "residual" image on
the phosphor plate that can interfere
with the next image. These indirect
systems are more time consuming, but
do result in a "digital" image that
can be subjected to EIP. An advantage
of PSP systems is a wide dynamic range
(like gray scale) which exceeds 10,000:1.
This more than compensates for their
lower spatial resolution of 6-9 lp/mm.
Digital Receptor Systems
(not currently available in North
||up to 8 lp/mm
||64 x 64
From the preceding discussion, we
see that there are many digital x-ray
systems to chose from, that the systems
have many advantages over conventional
film-based radiography, that major
companies like Eastman Kodak are continuing
to transition to digital products,
and that the change to digital in
both our consumer and professional
worlds is inevitable. The question
to ask yourself is not "Should I change?",
but rather "When do I change?". My
suggestion is to do it sooner than
later. If you've adopted computers
into your office, it's only a matter
of time before you will "go digital".
1. Miles DA: Advances in Imaging in
Oral Medicine, Alpha Omegan 94(2):
2. Miles DA: Understanding Digital
Radiography, 2001 Technology Guide,
Dental Practice Report, 8-12, 2000.
3. Miles DA, Langlais RP and Parks
ET: Digital X-rays Are Here; Why Aren't
You Using Them? CDA Journal 27(2):
(URLs) for the manufacturers in the
Cygnus Technologies http://www.cygnus-technologies.com/
Dentrix Dental Systems http://www.dentrix.com
Dentsply Gendex http://www.gendexxray.com/
Eastman Kodak http://www.kodak.com/US/en/health/index.jhtml
Instrumentarium Imaging http://usa.instrumentarium.com/
Planmeca, Inc. http://www.planmeca.com/
Schick Technologies http://www.schicktech.com/
Sirona USA http://www.sirona.com/e/index2.html