The review article on the fundamentals of digital radiography presented by Dr. Paul van der Stelt is a useful contribution ("Filmless Imaging: The Uses of Digital Radiography in Dental Practice,"
JADA 2005;136:1379–87
). However, there are several areas where clarifications are needed, both for Dr. van der Stelt’s article (several of the articles he cited are from my laboratory/clinic) and also for the guest commentary/editorial provided by Dr. Mel Kantor ("Dental Digital Radiography: More Than a Fad, Less Than a Revolution,"
JADA 2005;136:1358–62
).
Shortly after the discovery of X-radiation in Germany by Wilhelm C. Roentgen, the president of the British Physical Society is reputed to have noted: "I do not see how the X-ray can lead to results of any significance." The sentiments expressed in the commentary by Dr. Kantor are, in my mind, similarly blinkered.
The revolutionary component of digital imaging is not simply the display of "filmless" radiographs. It is, in fact, that those images are, for the most part, captured in a computer and displayed almost instantaneously, facilitating operative procedures that now can be image-guided. Digital images do not need to stand apart from film radiographs, as many practitioners use both. There is nothing wrong with this hybrid solution. Francis Mouyen invented his system for operative procedures, rather than as a replacement for film.
As chairman of the International Congress and Exposition of Computed Maxillofacial Imaging, I have noted a rapid transition in the field of dental and maxillofacial digital imaging. Twelve years ago, when the conference began, studies generally concerned simple diagnostic tasks.
Indeed, even the then-quite-primitive digital intraoral X-ray systems were found to have a similar diagnostic yield to film radiography, and that was for the few specific tasks where film radiography is known to perform well (for example, endodontic measurements and detection of moderately advanced proximal surface dental caries).
The strengths of digital radiography that have emerged have not been limited to "academic glass bead games" of comparing film and digital detectors. Rather, the strength has been greater use of digital imaging for guiding treatment. Often, this is now in three-dimensional applications that are impractical with film.
As a result of the growth in image-guided procedures, the journal Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontology has recently added a subsection on computer-guided treatment within its oral radiology section. And a new international journal on computer-assisted radiology and surgery will be launched by Springer Verlag early in 2006. This journal will include a section dedicated to computed maxillofacial imaging. Nearly all papers presented at the international conference I chair now reflect treatment, rather than simply baseline interpretation.
Francis Mouyen was perceptive, rather than blinkered, in his approach. Change is happening. These are exciting times, as anyone who visited the technical exhibit at the recent ADA annual session in Philadelphia must understand. The computer in general, and digital imaging in particular, are the enabling technologies that have made many new procedures a possibility.
While I endorse almost everything that was presented by Dr. van der Stelt, I would like to comment on one omission and one misleading conclusion. The American Dental Association Standards Committee on Dental Informatics WG 12.1 has been active in working with vendors of digital X-ray systems to ensure image-file interoperability, using the Digital Imaging and Communications in Medicine (DICOM) Standard.
This year, 13 vendors were able to prove conformance in time for the ADA annual session. It should be noted that, while this represents the lion’s share of systems presently available, there are still some vendors who have not come forward to have their images tested.
The suggestion that all digital systems are equal is misleading. An image for which there is no assurance of interoperability and maintenance of image integrity and the fidelity of identifying tags should not be considered equal to images from vendors who have achieved conformance in ADA WG 12.1 tests.
Further, digital sensors vary in many respects, and the perceptive dentist needs to carefully review multiple characteristics in order to make the appropriate choice for her or his own practice. Areas of question include, but are not restricted to, DICOM conformity; compatibility with the office’s practice management software; speed of operation (CCD and CMOS systems result in an almost instantaneous image, but some photostimulable phosphor systems are as slow as film processing); sensor durability (intraoral phosphor plates are relatively easily scratched); measured spatial resolution; contrast resolution; signal-to-noise ratio; cost, including warranties; and available sensor sizes.
Dr. van der Stelt’s article clearly illustrates that there are variations between systems in the range of acceptable radiation doses to obtain diagnostic images. Presumably, this factor is also one that consumers of digital systems might wish to weigh. A wider acceptable exposure range reduces the possibility of exposure error, but can also permit excess radiation dosages to be used.
Dr. Kantor can continue to enjoy his dial-up, landline telephone and monochrome television. I prefer a touchtone cellular phone and high-definition color television. While I still do use X-ray film for some purposes, my patients are also benefiting from the latest technologies in digital imaging, when these methods are of value. DICOM data sets from my cone-beam CT are beamed to different vendors of guides for dental implant placement, and to make laser-generated models for oral surgery planning.
The future of dentistry is with those who have a desire to move forward. Digital radiographic and visible light images are the building blocks that will eventually take the dentist from the role of free-hand artist to that of an architect of dental care. The computer is the major enabling technology.
