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Dental TI Blog

Confusion to Clarity: The Perfect CBCT 10 Steps to Making the Right Choice.

There are at least 50 different CBCT units in the US market. Selecting the best CBCT for your practice can be a confusing task. Every salesperson you speak with will try and convince you that they have the best CBCT solution for you. How do you decide? Selecting the best Cone Beam Computed Tomography (CBCT) system for your dental practice is a crucial decision that can impact the quality of your service, your workflow, and your overall patient satisfaction. With a vast array of CBCT systems in the market, it can be challenging to find the one that suits your unique needs. Here's a step-by-step guide to help you make an informed choice:

Step 1: Understand Your Clinical Needs Start by assessing the needs of your practice for CBCT based on the procedures that you will be performing with the CBCT scans that you acquire. Consider the type of dental procedures you perform regularly. Will you be using CBCT for endodontic procedures, implant planning, oral surgery, orthodontics, or a combination? Do you need a device that can scan a single tooth with detail, a specific quadrant, or the entire maxillofacial area? Understand the field of view (FOV) that suits your clinical requirements and start by narrowing the field to just that machine.

The illustration below illustrates the nine different FOVs offered by the J.Morita 3D Accuitomo 170. This illustration is used to show the varying FOVs that CBCT can offer.

Step 2: Set Your Budget Dental CBCT systems can range significantly in cost. At the low end of the new CBCT price spectrum, small and medium FOVs start around $50K. Keep in mind that these “economy” units are less expensive for a reason. Typically, the build quality and image quality are going to be inferior to the most expensive units in the small to medium price range which can be in the $70-$80K range. Bear in mind that the overall cost includes the price of the system, installation, training, maintenance, and possible software updates. Some warranties include parts and labor while other warranties cover only parts. It is important to read your warranty and understand the limitations and exclusions. Also, realize that most warranties do not cover the PC and the IT maintenance related to the PC.

Remember, the cheapest is not necessarily the least costly as ROI determines true cost over a period of time. If you do not see the quality needed for diagnosis and the CBCT does not last until fully amortized, then the cheapest CBCT can actually be the most costly. This defines the difference between price and cost which is driven by true value.

Step 3: Analyze Image Quality. Image quality can vary widely amongst different FOVs and different CBCTs. Normally, smaller voxels produce greater detail. A voxel, or volume pixel, is the 3D equivalent of a pixel. It represents a value on a regular grid in three-dimensional space. These values can represent various types of data, such as color and transparency, in computer graphics and similar fields. The size of the voxel influences the resolution of the CBCT scan: smaller voxels result in higher resolution but require more computing power and time to process. Conversely, larger voxels result in lower resolution but are quicker and less computationally intensive to process. High-quality CBCT systems should produce images with high resolution, low noise, and precise details. However, small FOVs for endo as an example, will be taken with a lower voxel size (typically .075-.125mm) and show greater detail than a larger FOV scan taken for the airway. Larger FOV scans usually are taken with a voxel size of .20-.40mm as the detail required to determine airway obstruction is less than what is required to see a root fracture. Below are examples of a small FOV high-resolution endo scan and a large FOV low-resolution airway scan. Both are perfectly suited for their respective applications.

Hi-Resolution .08mm endo scan from the JMorita X800 F40

Low-Resolution .40mm Airway Scan

One way to evaluate image quality is to draw an MPR (Multi Planar Reconstruction) on the axial image and evaluate the slices with varying slice thicknesses and the smallest interval, typically .5 mm. The thickness refers to each slice and the interval is the spacing from slice to slice. Looking at this detail is where you will see quality separation among the various CBCT machines. Evaluate the detail in the minimum slice thickness as that represents a single voxel. The image presented will have more graininess than an image that has a greater thickness as it is a thinner slice with less information. An example of different slice thicknesses from slices taken from an MPR at the same location. For typical use, a 1mm thickness is very readable while appearing smooth. For evaluating fractures, being able to look at an image in the thinnest slice can be very helpful. Comparing the smallest voxel quality of scans is a good way to see what details the prospective CBCT is able to capture.

Example of an MPR curve. Slices are represented in the three panels.~ 1mm slice thickness.

Single Voxel .08mm thickness ~6 Voxels .5mm thickness ~12 Voxels 1mm thickness

Another way to evaluate true image quality is to request the manufacturer’s MTF numbers for each FOV and resolution from a particular machine. The modulation transfer function (MTF) is well known as a crucial parameter in the quality assurance of computed tomography (CT) scanners, which provides detailed information on both the contrast and resolution of CT images. Read the following study to learn more about MTF in the evaluation of CBCT image quality.

Study on MTF with the J Morita Accuitomo 170.

Step 4: Evaluate Usability Ease of usability involves the workflow from integration to your PMS, patient positioning, and image acquisition, to image reconstruction and visualization. Integration from PMS should minimally allow for creating a patient in the PMS (Dentrix, Eaglesoft, Open Dental, etc.) with one click of the mouse. When positioning a patient, it is important that the CBCT you choose allows for imaging short neck, big shoulder individuals as the C-Arm will often collide with the tops of the shoulders. Some CBCT machines allow for increasing the vertical distance between the rotating C-arm and the tops of the shoulders, while others do not. Non-adjustable machines are more prone to shoulder collisions upon rotation. There are patient positioning tricks to pull the tops of the shoulders down, but, it can be very useful if the CBCT unit allows for vertical adjustment of the sensor and tube head that hang down as the C-arm rotates.

Evaluate the ease of acquisition and the interface of the CBCT system. Acquisition of the CBCT image is critical in resultant quality. This means proper positioning and stability of the patient will determine the quality of the result. The center of focus of a CBCT scan always reflects the highest accuracy in the overall scan. For small FOVs like 40mmX40mm scans used for endo, getting the center of focus on the mid roots of the tooth being scanned is critical to optimizing quality. Using a CBCT with a two-directional scout function allows for taking a low-dose 2D coronal and sagittal image and then picking the exact location in each image that will be the center of the 3D scan. This means you will have the greatest level of detail where the scout image is taken. In the image below, that location is marked with a green crosshair and a number one.

Example of two-directional scouting offering precise locating for a 40X40 FOV.

The software provided by the CBCT manufacturer should allow for fast reconstruction times after the images are taken and easy tools to allow for the visualization of areas of concern quickly. Most programs allow for exporting volumes with a “lite” version of the software that will allow for evaluating the image quality and software functionality. It is important to get different FOV volumes from each manufacturer to evaluate carefully and objectively without a salesperson present.

Ease of usability involves the workflow from integration to your PMS, patient positioning, and image acquisition, to image reconstruction and visualization. Objectively evaluate the software. Does it offer the features you need like implant planning, airway analysis, TMJ analysis, cephalometric analysis, etc.? Remember, all CBCTs generate DICOM information. So, if you really like the quality of a particular unit and don’t like the planning software, you can choose to use different software for airway and implant planning. BlueSky Plan is a great option as the software is a pay as you use it fee where you only pay when you export STL scans for a purpose such as printing a surgical guide.

Example BlueSky Plan and creating a surgical guide