CONE BEAM Article
Getting the Most Out of Your CBCT: Positioning and Image Optimization Tips
Dr. Steven Hernandez
CDOCS Faculty
OK, you’ve invested in that CBCT technology and are ready to dive into the world of 3D headfirst. You also have a seasoned team who have embraced technology in the office as well. However, the quality of the scans isn’t what you’re expecting. In some volumes, the anterior teeth are missing and occasionally one side of the mandible. In others, the image is distorted. You know your team knows how to take radiographs…you had a Panorex machine for years.
Now you’re rethinking your decision and wonder if you have a lemon of a machine. In this post, let’s discuss the steps necessary to obtain a quality image that is crisp, diagnostic, and how to correct for bad patient positioning in the machine.
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This image is the default image that appears when you open a 3D volume on a patient for the first time. You will see that there are five individual windows and in the top left, panorama, you will see the inspection window front and center in the image.
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If I enlarge the panorama view, which also removes the inspection window, you will see that it appears as though there is thinning or missing hard tissue in the right mandible. Additionally, it appears as though the incisal edges of the mandibular teeth might be chipped and perhaps thinning of the maxillary anterior as well. This less-than-ideal image illustrates what I commonly see when an image is first captured on a patient prior to adjustment. So, what steps do we need to take to correct it?
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When a new scan is captured on a patient, everyone on my team knows that when you initially open a volume, we must take the following steps to optimize the image. On the right-hand side of the screen you’ll see there are two tabs, one is listed as TOOLS. Click on it to open your digital toolbox. You see that two of the boxes are highlighted; 3D and the one below it that looks like crosshairs. Highlighted boxes indicate what is active within the volume. Note the 4th icon over under the heading of ‘Tools’ above the red arrow.
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Clicking on this icon takes us to this view. On the right-hand side, you’ll see some preset jaw shapes and the default curve thickness of 30mm below them. This entire process I’m about to describe takes about 5 seconds but let’s take our time reviewing it so you understand the why behind what I recommend. In my office, we select the bottom middle jaw preset and use that 99.9% of the time. Selecting the bottom middle preset idealizes the image for all the patients in my practice and I’ve yet to see a reason to choose another preset. The curve thickness below the jaw presets indicates the buccal-lingual border/thickness noted below the pan view in this screen. You’ll notice what looks like the letter U and in the center of this is a continuous line with various yellow dots. Again, that 30mm measurement references the border/distance of that U shape from buccal-lingual (double red arrows). The software defaults to 30mm and it’s important to note that any radiographic data outside of that U shape border will not be present. Look closely at the image. You’ll see that some of the incisal edges extend beyond the buccal border at the bottom of the screen (green arrow). This is why it appears as though the anterior teeth are either missing or severely thinned in the above PAN reconstruction.
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Here, we can see that the bottom middle jaw preset was selected, and the curve thickness was adjusted as wide as it can go; 50mm. Looking to the left, you can see how the buccal-lingual distance of that U shape has greatly increased. More importantly, look at the above pan view and you’ll note that we now have a complete are present as well as the left mandible.Image; all maxillary teeth
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Now let’s talk about how to correct a bad position. Whether a new team member takes the scan and doesn’t position them properly or perhaps you have a patient who has a physical limitation and can’t upright their head, the image can be corrected. If you see a scan like this, there’s an easy way to correct it without having to re-expose the patient.
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Again, the same TOOLS tab on the right side of the screen is clicked and we go into the same tool as before.
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Now we’ve chosen the correct jaw preset and increased our curve thickness, but this hasn’t corrected the bad positioning. To correct this, look at the bottom left of the screen and you’ll see a tab labeled 3D align.
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Clicking this tab takes us here where we have 6 individual windows. The top right window shows how the patient was positioned when the image was captured. The goal in this screen is to position that top right image as though the patient were looking right at you. Think about them ideally mounted in an articulator. Now notice the three bottom images with different colors; red, green, blue. In each of these boxes, there is a circle with a corresponding ball of the same color. Left click and hold on those circles and you can rotate the image and correct the bad positioning.
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While there is no ideal number or setting to look at in this window, what you will do is adjust those circles while looking at the top right image so that the patient appears to be looking at you and the occlusal plane is level. Once you’re satisfied, click the OK tab in the bottom right of the screen.
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We now have an image that is ideal to evaluate, and you now know how to correct for bad positioning and how to adjust the settings so that all of the radiographic data is available for your review.
Conclusion
When finished, click OK and you are returned to the original 3D layout. These functions take mere seconds and only need to be done the first time the volume is opened on a patient. Once set, they are saved so this function doesn’t have to be done each time you open that volume.
Related CDOCS Hands-On Workshops
Implementing Cone Beam for Practical Utilization (CB110)
Get comfortable with cone beam technology through hands-on training in CBCT hardware operation, full volume review, and Sidexis and Sicat software suites, including introductions to CAD/CAM integration, airway analysis, and implant and endodontic applications to unlock your system’s full potential.
Maximizing Diagnostic Efficiency with Cone Beam (CB210)
Enhance your ability to systematically review CBCT volumes, identify and categorize radiographic abnormalities, and effectively collaborate with maxillofacial radiologists.
