I am very pleased with the comments of Dr. Farman, not least because he seems to agree with the general message of my article. I am a bit confused, however, when he talks about an omission and a misleading conclusion.
The misleading conclusion, if I understand Dr. Farman’s letter correctly, is that "all digital systems are equal." I have reread my article, and I could not find a statement like this, or even a paragraph suggesting that this is the case. If his comment relates to the fact that not all sensor systems are completely DICOM-compatible, I agree that this is true.
On the other hand, however, I want to emphasize that DICOM is not the ultimate solution for every general practitioner. First of all, DICOM is a comprehensive standard. Not everything described in the standard is always essential. Even the Digital X-ray, or DX, supplement to the DICOM Standard, which specifically pertains to digital radiography in dentistry, is quite extensive. That is one of the reasons why the ADA, by means of the Working Group 12.1, has attached importance to the development of the dental subset of the DICOM standard, which has been published as ADA Technical Report 1023, "Implementation Requirements for DICOM in Dentistry."
It is too easy to say that a sensor should be in conformity with DICOM. The user (that is, the general practitioner) first must define in what context he or she needs to make use of the DICOM connectivity. If he or she is using one or only a few sensors within his or her practice, there are other solutions available to store the image data from different sensor systems together in a single uniform database. Other solutions are easier to implement from a technical point of view and are therefore more user-friendly. Only when the dentist wants to exchange images with colleagues or other clinics is DICOM the most effective solution.
Most sensor software packages, therefore, are able now to read and write so-called DICOM studies on a CD-ROM. If the sensor manufacturer has achieved conformity in ADA WG 12.1 tests, it can be assumed that the software has this functionality. Otherwise, the user has to ask the vendor to prove conformity. It is good that the number of companies that use the WG 12.1 tests to show their conformity is increasing every year.
When sensor systems are used in a large clinic that is DICOM-based, the implementation of DICOM compatibility is much more complicated, exceeding the content of Technical Report 1023. In that case, specialized knowledge is required, which is clearly beyond the scope of my article.
Again, it is not completely clear to me to which section of my article Dr. Farman’s comment about an omission refers. He lists nine items that should be considered when choosing a sensor system. All items listed are important. It is a pity, however, that Dr. Farman did not include the most important parameter of all: the diagnostic performance of the sensor system, which encompasses all physical parameters and their interactions as they function in a clinical environment.
Spatial resolution, contrast resolution and signal-to-noise ratio (and there are other parameters as well) can be measured easily, and quite a number of articles have been published comparing sensors based on physical characteristics. However, a sensor that scores well on just a single one of the physical parameters does not always perform well in real life. That is because spatial resolution, noise and contrast interact and need to be described simultaneously. This is something to be aware of when choosing between different sensor systems. I encourage readers to take note of the paragraph on diagnostic-image quality on page 1386 of my article.
When I organized the first Symposium on Digital Imaging in Dental Radiology in 1990, it was just a satellite meeting of the (then) triennial European Congress of Dento-Maxillo-Facial Radiology. A few informal meetings preceded this symposium, and several formal ones would follow.
I remember how excited we were when, during one of these symposiums, we showed that we could transmit a radiograph from one side of the Atlantic to the other. We did this together with Dr. Farman. To prove that the transmission was not faked, a co-worker of Dr. Farman’s scanned a newspaper and showed us the date of issue of this newspaper.
Many other exciting things happened in consequence of the continuing evolution of digital radiology, and have been presented during conferences, symposiums and as articles in journals. I hope we will be able to report new developments in this field in JADA in due course.
