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A Protocol for Creating Images from CBVI for the Practicing Orthodontist, Part I by Daniel S. German, DDS

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Quantum leaps in orthodontic diagnostic potential have occurred in the past decade. This has been primarily the result of the introduction of 3D imaging to dentistry. Digital 3D imaging has opened the window into the hard and soft structures of our patients, allowing us to:
  • pursue an analysis of "anatomic truth" as part of our diagnoses and interactive treatment planning,
  • diagnose in 4D (adding the element of serial images without the confounding issues inherent in 2D imaging, such as image distortion and altered angles of viewing and magnification),
  • create visual treatment simulations for orthodontic and orthognathic surgical movements,
  • simulate placement of temporary anchorage devices,
  • simulate placement of implants to ensure readiness to remove pre-implant orthodontic appliances,
  • simulate the prosthodontic replacement of teeth,
  • store records digitally, and
  • fabricate appliances using 3D images and models.

The focus of this article is on 3D and 4D diagnostics using cone beam volumetric imaging (CBVI), also known as cone beam computed tomography (CBCT). More to the point, this article will outline a "cookbook" that the clinical orthodontist and staff can implement to create and save the images obtained from 3D scans. Controversial issues such as when CBVI is indicated, who should read the data set, and the econometrics of 3D imaging can and should be debated in other articles.

The challenges of a quantum leap in our profession are manifold. Owning and maintaining the technology is an enormous expense, and drastic changes to the practice workflow are required, perhaps including an office remodel. Additionally, seasoned practitioners have not been educated on the technology or what to do with the new information. How do we use the data acquired from 3D and 4D imaging?

Let's break down the question into a more detailed set of questions: How do we view the data? Do we view the data when the patient is in the office, or after hours? Which images do we build for each patient? Which images do we save in the patient chart for future viewing? Which images do we share with the patient's other practitioners? How long do we have to wait for the profession to move toward a standardized protocol, or group of acceptable protocols for these?

The answer to the question of how long it will take our profession to develop the protocols and accepted methods of analyses is becoming clear: a long time. One needs only to reflect back on the last substantial improvement in diagnostics, the lateral cephalogram. B. Holly Broadbent published his classic article describing the use of the cephalometric radiograph in 1931.1 However, regular use and development of cephalometric analyses were not put into practice until the 1950s. CBVI was introduced to dentistry in 1998,2,3 and remarkably, for 12 years there was not a proposed method of analysis or sample montage of images that could be created with 3D imaging. Taking into consideration the length of time required for our specialty to adopt new technology, I felt the need and desire to accelerate the process. Hence, I published a template for use with CBVI in the April 2010 Journal of Clinical Orthodontics.

There are thousands of CBVI machines installed in the U.S. with more than 30 vendors manufacturing the machines. At last count, approximately 20-plus orthodontic residences are using CBVI as their principle method of imaging. One could estimate that there have been 100,000 or more 3D scans of orthodontic patients. Since we are making the images, it is our responsibility to have an effective methodology for creating, assessing, sharing and documenting the images created from CBVI data. For those not familiar with CBVI, the machine looks very similar to a combination pan-ceph machine (Fig. 1).

It is a digital machine that creates data that is "processed" by a computer (no X-ray picture is directly created by the machine). A trained orthodontic technician can create a series of images that resemble traditional X-rays and myriad other images to form the template previously published.4 The process of making the patient scan is approximately one minute long. The time required by an experienced technician to build the images for our template (the German template) in Dolphin Imaging is approximately six minutes (Fig. 2).

The German template of images is intended to ensure that a comprehensive evaluation of the data occurs for every patient, and that the appropriate data is shared with colleagues. Each new patient scan is scrutinized as articulated in the publication, viewing all data in three multiplanar views (sagittal, axial and coronal), followed by an additional review of the images created in the German template. A very basic explanation of the purpose of each of the views and the information gleaned from them is described in the JCO publication.4

The remainder of this article serves as a "cookbook" for creating the default settings on the Dolphin Imaging and TxStudio software packages and the six-minute process for you or your technician to create/save the desired images on the computer using Dolphin software. When building the template for the first time, it will take a doctor or staff member at least 30 minutes to work through the instructions. Although the instructions should be adequate for the 3D novice, familiarity with Dolphin and TxStudio is helpful. More details regarding the nuances of the software can be gleaned from Dolphin and TxStudio training materials.

You may load the complimentary default German Dolphin template from an installer written by Dolphin Imaging available at www.germanorthodontics.com. Click on the box labeled "3D imaging training" or use the direct link (http://germanorthodontics.com/orthodontic-3d-imaging-training/). The automatic process will take approximately one minute to load. To watch the German Orthodontic staff create the images in Dolphin as described in the article, click the header labeled "3D imaging training." Under that header you can also view a video we produced, "a primer on diagnosing and treatment planning with 3D CBVI."

Saving Patient Images to the
German Layout Dolphin Template
  1. After making the patient's 3D CBVI scan, open Dolphin and click "Patients" to open the "Patient Lookup" window. Then click "New Patient…" and select "New Patient from DICOM."

  2. Navigate to the DICOM file storage location. Select the patient's ID and click "Open."
  3. Select the most recent scan date and click "Open."
  4. Select the DICOM folder and click "Open."

  5. Select any .dcm file and click "Open." (*Note: If the patient already exists in the Dolphin database, the existing patient profile will open at this point.)
    • To build images for an existing patient with a previously loaded DICOM file, click "Patients" to open the "Patient Lookup" window and search for the desired patient. Click "OK," then select the appropriate time point. Click "3D" and select the "Edit" option.
  6. After the DICOM data has loaded, first click "Orientation" to open the "Orientation Calibration" window. Select the "Right" tab at the top of the window. To orient the image, click and drag the mouse to rotate the skull until the left and right orbits and mandible are superimposed on each other as able. Click "OK."
  7. To save the hard frontal image, click "Send Snapshot," then click "Save to Dolphin Layout/Database."
  8. Click the square indicated below (the "Image Title" will automatically load with "Hard Frontal"). Then click "Save."
  9. Click "Sinus/Airway." First, focus on the upper left side of the screen to outline the airway. Place your mouse to the right of the opening of the airway and click to make the first green point, then move the mouse over the airway passage to the left and click a second time to make another green point on the opposite side. (The vertical height of the upper line should be determined by the doctor and used consistently for each scan made.) Next, move the mouse down along the side of the airway and click to make a third green point to the bottom left of the airway, then move the mouse over the airway passage to the right and click a fourth time to make a green point to the bottom right of the airway. Finally, move the mouse back up along the side of the airway and reclick on the first green point to complete the airway outline box.

    Click the "Add" button (located under the lateral picture) and a small, yellow dot will populate. Use the mouse to drag the yellow dot into the airway area. (See steps 1-3 shown on the top right picture for additional assistance.) Click "Update Volume."

    Once the airway volume has updated, focus on the upper right side of the screen. Check the box to "Enable Minimum Axial Area." Then drag the red lines to the top and bottom of the airway outline (the top red line should be directly beneath the top green line and the bottom red line should be directly above the bottom green line) and click "Find."

    Depending on the doctor's preference, you may choose to adjust the slide bar next to "Soft Tissue" to slightly change the look of the soft tissue. Select the "Right View" icon (see diagram below for location) and check the "Hard Tissue" box.

    Then click the "Volume View" icon in the upper left corner and click "Send Snapshot" and select "Save to Dolphin Layout/Database."
  10. To save the airway image, click the square indicated below (the "Image Title" will automatically load with "Translucent Volume"). Then click "Save."
  11. Click "OK" to exit the "Sinus/Airway" window. Then click "Build X-rays." Click "OK" in the pop-up window that appears and the "Build X-rays Tool" window will open. (See above.)

  12. Select "Lateral" from the "View" drop-down menu and click "Apply." Adjust the "Sharper" slider and "Dolphin 1" Level to the doctor's preference. [*Note that the ceph generation preferences should be selected according to the desired protocol; orthogonal (1:1) or perspective (magnified) projection]. Then select "Send Snapshot" and "Save to Dolphin Layout/Database."
  13. To save the lateral X-ray image, click the square indicated below (the "Image Title" will automatically load with "X-ray Lateral"). Then click "Save."
  14. Remain in the "Build X-rays Tool" window and select "Panoramic" from the "View" drop-down menu. Adjust the top white line to the bottom of the orbit, and the bottom white line to below the chin. Adjust the blue line to the left of the condyle and the red line to just below the crown of the lower teeth.

    Focus on the lower left side of the screen to create the "Arch Path." Begin below the blue line on the left side and click to place the first red path point. For optimal visual quality, place two path points along the arch, then click in the middle of every tooth to add path points. Double click below the blue line on the right side to complete the path. Then click "Apply." Adjust the "Sharper" slider and the "Dolphin 1" Level to the doctor's preference. Click "Send Snapshot" and "Save to Dolphin Layout/Database."
  15. To save the panoramic X-ray image, click the square indicated below (the "Image Title" will automatically load with "X-ray Panoramic"). Then click "Save."
  16. Select "TMJ" from the "View" drop-down menu. Adjust the white lines to border the condyle (the top line will be near the bottom of the orbit and the bottom line will be roughly one-third of the way down the jaw) and adjust the red line to bisect the center of the condyle. (*Hint: While adjusting the red line, focus on the lower left image. The condyles are shaped like kidney beans, so when the "beans" appear, you know the red line is positioned correctly on the condyle.) Focus again on the picture in the lower left of the screen. Adjust the lower red path points (with the yellow boxes around them) so they are in the middle of each condyle. Adjust the upper path points until the red lines are perpendicular to the condylar axis. The lines should be bisecting the condyles. Select "Sagittal" from the "Direction" drop-down menu and click "Apply."

    Focus on the upper right section of the screen. Adjust the yellow hash marks to ensure the clearest view of the condyle, and then adjust the "Sharper" slider as needed. Select "Send Snapshot" and "Save to Dolphin Layout/Database."


  17. To save the sagittal TMJ X-ray image, click the square indicated below (the "Image Title" will automatically load with "TMJ Sagittal"). Then click "Save."
  18. "TMJ" should still be selected from the "View" dropdown menu. Select "Coronal" from the "Direction" drop-down menu. Click "Apply." Adjust the yellow hash marks in the upper right-hand corner to ensure the clearest view of the condyle, and then adjust the "Sharper" slider as needed. Select "Send Snapshot" and "Save to Dolphin Layout/Database."
  19. To save the coronal TMJ X-ray image, click the square indicated below (the "Image Title" will automatically load with "TMJ Coronal"). Then click "Save."
  20. Select "Frontal" from the "View" drop-down menu and click "Apply" to build the frontal X-ray image. Adjust the "Sharper" slider and "Dolphin 1" Level to the doctor's preference. [*Note that the ceph generation preferences should be selected according to the desired protocol; orthogonal (1:1) or perspective (magnified) projection.] Then select "Send Snapshot" and "Save to Dolphin Layout/Database."
  21. To save the frontal X-ray image, click the square indicated below (the "Image Title" will automatically load with "X-ray Frontal"). Then click "Save."
  22. Click the "X" to close the "Build X-rays Tool" window.

  23. Select the "4-Equal Slices-Volume Layout" icon at the top of the screen. Adjust the crosshairs to the doctor's preference on each of the three slice views. Adjust the green line until the "Coronal Slice" focuses on the first molars. Move the red line so the "Sagittal Slice" shows the right centrals. Adjust the blue line so the "Axial Slice" shows the lower root tips.

    After all three pictures are adjusted, select the "Show/Hide Crosshairs on the Slice Views" icon (that looks like four black boxes) to remove the lines from the images. Then individually select each of the three ("Sagittal," "Coronal" and "Axial") icons. For each picture, when it is enlarged to be the only image on the screen, save by clicking "Send Snapshot" and choosing "Save to Dolphin Layout/Database."
  24. To save the sagittal slice, click the square indicated below (the "Image Title" will automatically load with "Sagittal 1s"). Then click "Save."
  25. To save the coronal slice, click the square indicated below (the "Image Title" will automatically load with "Coronal 6s"). Then click "Save."
  26. To save the axial slice, click the square indicated below (the "Image Title" will automatically load with "Axial Mandible"). Then click "Save."

  27. Click the "X" to close the window.

  28. Click "Digitize."
  29. Select your preferences in the "Digitize Setup" window, then click "Start Digitize."

  30. To trace the ceph, follow the written and spoken instructions that automatically activate. When the tracing is complete, click "OK" and "Digitized – Ceph Lateral" will automatically save into the Image Layout. (The current layout includes the untraced frontal ceph. A traced frontal can be saved off of the template. It can be viewed by choosing "Everything" from the "Layout" drop-down menu.)

  31. Choose "Image Layouts" from the "Layout" drop-down menu. Then click "Capture/Scan" to begin importing patient intra/extraoral photos.

  32. In the "Capture Setup" pop-up window, click "Start Capture."
  33. Click "Browse" to navigate to the photo storage location. Drag the appropriate thumbnails from the list on the right to the specified photo positions and edit as needed, then click "Save."
  34. The German template is complete!
References
  1. Boadbent BH. A New X-Ray technique and Its Application to Orthodontia, Angle ortho. Vol 1. No 2 April 1931
  2. Cattaneo, P.M.; Bloch, C.B.; Calmar, D.; Hjortshøj, M.; and Melsen, B.: Comparison between conventional and conebeam computed tomography-generated cephalograms, Am. J. Orthod. 134:798-802, 2008.
  3. Mozzo, P.; Procacci, C.; Tacconi, A.; Martini, P.T.; and Andreis, I.A.: A new volumetric CT machine for dental imaging based on the cone-beam technique: Preliminary results, Eur. Radiol. 8:1558-1564, 1998.
  4. German D, German J. Cone Beam Volumetric Imaging: A Two minute Drill. J Clin Ortho 2010; April 2010, 253-265

Author's Bio
Dr. Dan German has a private orthodontic practice in Dayton, Ohio. He is a part-time assistant clinical professor at The Ohio State University and is a consultant to the University of Louisville Division of Orthodontics. He has been the keynote speaker at orthodontic association meetings from Alaska to South Africa, and most recently at New Zealand's University of Otago. Dr. German's article presenting a protocol for using 3D CBVI in orthodontic diagnosis and treatment planning was featured in the Journal of Clinical Orthodontics. He has also been published in the Journal of the American Dental Association and the American Journal of Orthodontics and Dentofacial Orthopedics. He is most passionate about his role in raising seven children with his wife, Teri.
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