Dr. Shwartz asks us:
Does anyone have information regarding the radiation dossage you give to a patient when you routinely employ cat scans, including cone beam ones, to the treatment planning for dental implants?
What is the comparative radiation between CAT procedures for dental implants and either panoramic or conventional dental x-rays. Do you think CAT procedures should even be used routinarily for perhaps an anterior implant in order to make flapless surgery instead of conventional surgery? Is it worth it? Do the benefits of such a procedure exceeds the potential risks of overradiation?
I routinely take scans on every patient and not just implant cases. The amount of radiation is equivalent to a PAN and 7 vertical bitewings, but the information is 100 times more valuable. You still get more radiation on sunny days than with this. Our scanner is about 1/200th the amount of radiation as a medical equivalent so it’s much better and its formulated for dentistry. My opinion is that everyone, not just surgeons, will have CT machines as opposed to PANs. Fantastic practice builder and increases your comfort 1000%. Can’t say enough.
We currently use a NewTom 3G. It takes 360 axial images with the lowest radiation dose of all focused cone beam scanners. It is typically 20-40X less radiation than traditional CT, comparable to panorex (or less if taken in the 6 inch field of view). We have not touched our panorex since the day the scanner was installed. We can do a panorex view and then do tomos or any other views we need with the same or better resolution than a panorex. Often we will take multiple scans as the case progresses as we did when only using the panorex. In our more complex cases, we surgically navigate the procedure with outstanding results because of the lack of distortion – even more important for flapless surgery. Would recommend to anyone placing implants.
Thanks a lot for your advice.
Kindly tell us what is the exposure time with these scans?
Dose varies between CBCT systems and is also dependent on the selected field of view (FOV)and the number of basis images to be acquired. While a figure of dose equivalent to 4-12 panoramic radiographs is a rough and ready guide, it should be remembered that this can either be an over- or under-estimation dependent on the actual exposure settings and FOV. The comparison to medical multi-slice CT of say one-tenth to one-20th the dose is again just a rough estimate based upon the manufacturers’ recommendations for multi-slice CT exposure. Often, it is possible to reduce the multi-slice CT dose below those recommended without loss of critical diagnostic quality. This is particularly the case for bony structures.
So my advice, is that CBCT is a relatively low-to-middle dose range technique. Following the ALARA principle, one should apply selection criteria, minimize the FOV, and select the minimum number of basis images needed for the particular case.
As an aside, it is the responsibility of the practitioner to read all of the information in any diagnostic image for which they are responsible. This is important to maximize the benefit to risk ratio for the procedure. Practitioners who use CBCT and are not fully trained in oral and maxillofacial radiology should consider submitting image volumes for the scruitiny of a competent radiologist. Better safe than sorry.
Thanks Allan for the reminder.
We often forget the ultimate responsibility and possible negligence as a result when we overlook or worse, missed vital, relevant information from these scans. We are seeing a lot more than conventional panoramas but are we trained to interprete and analyse them?
The quality of images generated by CBCT nears the level of multichannel CT. We have detected several “incidental” extra-oral findings which were of clinical import and required additional intervention. Examples of such can be seen on our website.
The maximum intensity images (MIPs) and 3D rendering is extremely useful. However, the source images typically are where the subtleties of disease will be found. These need to be diligently scrutinized.
Dan Reidman
President, Essential Diagnostics