CT Scanning Protocol For V2R Guided Surgery Solutions

CT Scanning Protocol For V2R Guided Surgery Solutions

2 V2R CT Scanning Protocol \\ Contents Contents General requirements... 3 V2R Dual Scan Protocol... 5 V2R Single Scan Protocol... 8 Overview... 10 Checklists... 11

3 V2R CT Scanning Protocol \\ General requirements General requirements Why is a V2R-specific protocol necessary? Aren t all CT scan protocols equivalent? Three-dimensional imaging of the patient's maxillofacial anatomy with the use of Computed Tomography (CT) data is a common denominator to most guided surgery approaches, some of which however may include proprietary instructions and/or devices, and may be limited to specific applications. As such, V2R requires observing its specific CT scan protocol, designed with the following objectives in mind: Facilitating the procurement of prerequisite items from the clinician s preferred local dental laboratory; Capturing data enabling prosthetically-driven treatment planning; Being adaptable to most patient conditions; Future-proofing the CT scan data, increasing the likelihood that it will be usable despite known and commonly observed issues. The V2R CT Scanning Protocol (below) can be performed using either a: Cone-beam (CB)CT scanner - typically used in dental clinics, usually with a vertical gantry axis and the patient in seated or standing position, or a; Fan-beam CT Scanner - typically used in hospitals and radiological imaging centers, usually with a horizontal gantry axis and supine patient position. Prior to scanning a patient, please make sure you have identified which configuration on your CT scanner will yield optimal results. Among others, the aspects listed below should be considered: Field of view (FOV): The volume must be sufficient to include the patient s entire arch and scan appliance (when applicable). Small FOVs limited to specific regions of interest, often used for periodontics applications, are not sufficient. To prevent exclusion of structures of interest from the FOV, each scan should ideally focus on a single arch. Gantry tilt: If available, this setting should be set to none/ 0 degree. Dose-affecting parameters: Tube potential (kvp), tube current (ma) and acquisition speed (s), among others, affect both the resulting radiation dose and image quality. CT scanners may allow independent adjustment of those parameters and/or allow the selection of pre-determined values within pre-sets. Any adjustment of those parameters will imply trade-offs on both aspects, and their impact on different structures (e.g. soft tissue, bone, teeth, scan appliance markers and existing implants) should be considered. Reconstruction settings: The settings used should prioritise yielding images of adequate contrast and resolution and refrain from using any compression algorithm. V2R requires a slice thickness/voxel size of 0.5mm maximum, to maintain its observational error below 1mm (approximated as twice the slice thickness value). Data export: The CT scanner software must have the ability to export the CT data in the DICOM format (large series of files with the *.DCM or *.DICOM extension).

4 V2R CT Scanning Protocol \\ General requirements The requirements listed above cannot cover all variations in the terminology, functionalities and adjustability featured in the vast CT scanner offering on the market. As such, when in doubt, V2R Biomedical would suggest referring to the equipment s documentation and seeking assistance from the manufacturer. Conducting and reviewing a CT scan of a stone model assembled with its corresponding scan appliance is a convenient method for; Verifying the accuracy of the scan appliance s outer surface and marker geometry produced by the selected scanning parameters and materials, and; In the case of a patient requiring a Dual Scan protocol, verifying the intimate fit of the scan appliance on the model, and getting an estimation of the fit to expect when worn by the patient. V2R Surgical Guides and dental laboratory-prepared scan appliances are designed to fit the patient s anatomy as captured by the provided impressions and CT scan data. As such, any misfit of the scan appliance or any change in the patient s anatomy occurring after the impression and/or CT scan may result in guide fit complications and adversely affect the surgical outcome. To reduce the likelihood of subtle anatomical changes being unnoticed, V2R suggests using: Polyvinyl siloxane (PVS) impressions dating less than 1 month and; CT scans dating less than 4 months. When available, take advantage of your CT scanner s scout view and dry run functionalities to confirm the patient s positioning in relation to the FOV and his/her and ability to remain immobile during the acquisition. For patients expected to have trouble or for whom a previous scan was deemed unusable due to movement artifacts, it is highly recommended to entrust the CT scan acquisition to a hospital or radiological imaging center. If the patient is scanned without your presence, practice the correct seated position of the scan appliance with him/her and provide the radiological imaging center with the V2R Scanning Protocol instructions.

5 V2R CT Scanning Protocol \\ Dual Scan Protocol V2R Dual Scan Protocol The Dual Scan Protocol is V2R s default protocol for both dentate and edentulous patients. It is designed to ensure that the resulting CT scan: Features an adequate primary reference for the surgical guide to rely on, and; Is less vulnerable to artifacts. Consistently favoring the Dual Scan over the Single Scan will minimize the occurrences where unexpected findings require scanning the patient again. The Dual Scan Protocol consists in conducting two distinct CT scan acquisitions: CT Scan #1: Scan of the patient wearing the scan appliance; CT Scan #2: Scan of the scan appliance (alone for edentulous patients, or assembled to the master model for dentate patients). The V2R specialist assigned to your case will superimpose elements 1 of the two resulting datasets, based on the markers embedded in the scan appliance visible on both CT scans. Next, this preliminary virtual treatment planning environment is validated for compliance with safety and effectiveness requirements. Finally, the desired setup data is then combined in order to move forward with prosthetically-driven implant planning. For edentulous patients, the scan appliance also serves as the basis for the surgical guide s design, and therefore must be prepared and scanned according to additional instructions, provided herein. 1 For dentate cases, additional model surface scans (.STL files generated by optical scanners such as the Dental Wings iseries) would be superimposed to the dataset prior to treatment planning.

6 V2R CT Scanning Protocol \\ Dual Scan Protocol Dual Scan Instructions Scan #1: Patient + Scan appliance Verify that any non-fixed restorations and jewelry worn above shoulder level by the patient are removed; Examine the scan appliance and ensure all radio-opaque markers are firmly fixed to the appliance. Verify that the scan appliance was built following the V2R requirements. Ask the patient to wear the scan appliance and verify that the fit is optimal. SCAN #1 Edentulous o o For an edentulous patient: Use the bite index to stabilize the scan appliance during the scanning procedure. For a dentate patient: Use the scan appliance s inspection windows to validate the fit. Ensure that the patient can maintain a static position during the scan acquisition. Inform the patient that he must not move or swallow in order to avoid movement artifacts. o o For an edentulous patient: Have the patient bite firmly on the bite index to stabilize the jaws. For a dentate patient: Have the patient bite on cotton rolls to stabilize and separate the jaws. (Any contact between opposing teeth must be avoided.) SCAN #1 Dentate Insert cotton rolls to separate lips and cheeks from the gingiva; (to get a better representation of the gingiva itself). For maxilla, ask the patient to keep the tongue away from the palate. Adjust the patient s position relatively to the CT scanner with the head upright. The occlusal plane must be parallel to the plane of image slice generated, with no tilt. Ensure the entire arch to be treated is included in the scanner field of view, and will be entirely captured during the acquisition. Conduct the scan acquisition according to the general requirements. Verify the resulting scan s compliance prior to sending the patient home. All scan appliance markers must be distinguishable on the CT-Scan images. Please ensure that markers are not lost in possible artifacts created by existing restoration, or uncaptured because of the field of view settings.

7 V2R CT Scanning Protocol \\ Dual Scan Protocol Scan #2: Scan appliance For an edentulous patient, position a radiolucent surface such as polystyrene foam block on the CT scanners platform, and place the scan appliance on it in the orientation it was when worn by the patient. SCAN #2 Edentulous Do not scan the bite index with the scan appliance. For a dentate patient, assemble the scan appliance on the master model and place the assembly on the CT scanner s platform. Verify the fit through the inspection windows prior to scanning. Ensure the entire scan appliance structure is included in the field of view, and will be entirely captured during the acquisition. Conduct the scan acquisition according to the general requirements; Verify the resulting scan s compliance prior to sending the patient home. SCAN #2 Dentate Recommended scan settings, for both scans (#1 and #2)* Gantry tilt: None (0 ) Slice thickness: 0.5mm Reconstructed slice increment: Same value as slice thickness The same general settings should be used for both scans. Depending on the system, different settings may be required for scan #2 to obtain an adequate digital representation of the scan appliance (mainly for edentulous patient, when the guide design is directly based on the scan appliance geometry). Recommended image reconstruction settings* Images required: Axial slices only File extension:.dicom or.dcm Format: Multi-slice or multi-file, as opposed to single-slice or single-file Saving options: Both scans must be saved in separate folders *Some settings may not be adjustable by your system. When in doubt, please contact the manufacturer s technical support.

8 V2R CT Scanning Protocol \\ Single Scan Protocol V2R Single Scan Protocol The Single Scan Protocol is appropriate only for dentate patients having stable and natural teeth remaining in each of the three sextants of the treated arch. To increase the likelihood that all your CT scans capture all essential data and are usable within a guided surgery workflow, V2R highly recommends conducting a Dual Scan Protocol whenever: Several teeth have undergone restoration; Stable and natural teeth are absent from any sextant. It is important to keep in mind that the teeth-supported surgical guide is always designed based on the digitized master model. 2 The V2R specialist assigned to your case needs to get accurate and compliant data in order to accurately superimposed the digitized master model and the patient s CT-Scan. It is important to keep in mind that the datasets are superimposed using landmarks such as teeth cups. If the teeth are not well defined in the CT-Scan data, it will then be difficult to accurately validate the registration, potentially introducing a discrepancy in the planned guide/anatomy/implant relationship, which may adversely affect the surgical outcome. As for the impression submitted to the laboratory, it must also be accurate and recent in order to get a proper registration with the patient s CT-Scan data. Otherwise, the fit of the surgical guide would be inaccurate or unstable, which may adversely affect the surgical outcome. 2 The digitized master model is normally generated by the laboratory (using optical scanners such as the Dental Wings iseries)

9 V2R CT Scanning Protocol \\ Overview Single Scan Instructions Verify that any non-fixed prosthesis and jewelry worn above shoulder level by the patient are removed; Have the patient bite on cotton rolls to stabilize and separate the jaws. (Any contact between opposing teeth must be avoided.) Insert cotton rolls to separate lips and cheeks from the gingiva; (to get a better representation of the gingiva itself). For maxilla, ask the patient to keep the tongue away from the palate. Adjust the patient s position relatively to the CT scanner with the head upright. The occlusal plane must be parallel to the plane of image slice generated, with no tilt. Ensure that the entire arch to be treated is included in the scanner field of view, and will be entirely captured during the acquisition. Ensure that the patient can maintain a static position during the scan acquisition. Inform the patient that he must not move or swallow in order to avoid movement artifacts Conduct the scan acquisition according to the general requirements. Verify the resulting scan s compliance prior to sending the patient home. In the Single Scan Protocol, direct contact with opposing teeth or radiopaque material must be avoided to: Enable the capture of occlusal anatomy and; Avoid possible artifacts from the opposite arch. Recommended scan settings* Gantry tilt: None (0 ) Slice thickness: 0.5mm Reconstructed slice increment: Same value as slice thickness Recommended image reconstruction settings* Images required: Axial slices only File extension:.dicom or.dcm Format: Multi-slice or multi-file, as opposed to single-slice or single-file *Some settings may not be offered by your system. When in doubt, please contact the manufacturer s technical support.

10 V2R CT Scanning Protocol \\ Overview Overview Dual Scan Protocol Dentate patient SCAN #1 SCAN #2 Patient Scan appliance Cotton Rolls Scan appliance Dual Scan Protocol Edentulous patient SCAN #1 SCAN #2 Patient Scan appliance Bite Index Scan appliance Single Scan Protocol DENTATE PATIENT ONLY (NOT RECOMMENDED) SCAN #1 Patient Cotton rolls

11 V2R CT Scanning Protocol \\ Checklists Checklists DUAL SCAN PROTOCOL EDENTULOUS PATIENT Steps Descriptions Done Scan #1 Patient + Scan appliance + Bite Index S1.1 Non-fixed restoration and jewelry were removed. S1.2 Scan appliance was prepared according to V2R requirements S1.3 Scan appliance correctly fitted in the patient s mouth. S1.4 Bite index was used to stabilize the scan appliance and jaws. S1.5 Patient was informed to maintain a static position. Patient was positioned so that the occlusal plane was parallel to the image S1.6 slice generated. Cotton rolls were inserted to separate the lips and cheeks from the gingiva. S1.7 Patient was informed to keep the tongue away from the palate (for maxilla). S1.8 The field of view is set to capture the relevant anatomy and markers. Scan settings used as recommended by V2R: Gantry tilt = 0 S1.9 Slice thickness 0.5mm Reconstructed slice increment = same as slice thickness Reconstruction of the images: S1.10 Images required: Axial slices only Format:.DICOM or.dcm, multi-slice Validation of the images prior to submitting to V2R All the markers are visible S1.11 The entire arch is visible No movement artifact detected Scan #2 Scan appliance alone S2.12 Scan appliance was installed on radiolucent material (such as polystyrene). The scan appliance was positioned in the scanner in the same orientation S2.13 it was when worn by the patient (without the bite index). S2.14 The field of view is set to capture the entire scan appliance. Scan settings used as recommended by V2R: Gantry tilt = 0 S2.15 Slice thickness 0.5mm Reconstructed slice increment = same as slice thickness Reconstruction of the images: S2.16 Images required: Axial slices only Format:.DICOM or.dcm, multi-slice Validation of the images prior to submitting to V2R: All the markers are visible S2.17 The entire arch is visible No movement artifact detected

12 V2R CT Scanning Protocol \\ Checklists DUAL SCAN PROTOCOL DENTATE PATIENT Steps Descriptions Done Scan #1 Patient + Scan appliance S1.1 Non-fixed restoration and jewelry were removed. S1.2 Scan appliance was prepared according to V2R requirements S1.3 Scan appliance correctly fitted in the patient s mouth. S1.4 Cotton rolls were added to stabilize and separate the jaws. S1.5 Patient was informed to maintain a static position. Patient was positioned so that the occlusal plane was parallel to the image S1.6 slice generated. Cotton rolls were inserted to separate the lips and cheeks from the gingiva. S1.7 Patient was informed to keep the tongue away from the palate (for maxilla). S1.8 The field of view is set to capture the relevant anatomy and markers. Scan settings used as recommended by V2R: Gantry tilt = 0 S1.9 Slice thickness 0.5mm Reconstructed slice increment = same as slice thickness Reconstruction of the images: S1.10 Images required: Axial slices only Format:.DICOM or.dcm, multi-slice Validation of the images prior to submitting to V2R All the markers are visible S1.11 The entire arch is visible No movement artifact detected Scan #2 Scan appliance assembled on the master model Scan appliance was adequately assembled to the master model. S2.12 (The fit can be verified through the inspection windows). The scan appliance (assembled on the master model) was positioned in S2.13 the scanner in the same orientation it was when worn by the patient. The field of view is set to capture the entire scan appliance and model S2.14 assembly. Scan settings used as recommended by V2R: Gantry tilt = 0 S2.15 Slice thickness 0.5mm Reconstructed slice increment = same as slice thickness Reconstruction of the images: S2.16 Images required: Axial slices only Format:.DICOM or.dcm, multi-slice Validation of the images prior to submitting to V2R The entire arch is visible S2.17 The occlusal anatomy is visible (patient not in intercuspation) No movement artifact detected

13 V2R CT Scanning Protocol \\ Checklists SINGLE SCAN PROTOCOL DENTATE PATIENT ONLY *NOT RECOMMENDED* Steps Descriptions Done Scan #1 Patient + Scan appliance S1.1 Non-fixed restoration and jewelry were removed. S1.2 Patient was informed to maintain a static position. S2.3 Cotton rolls were added to stabilize and separate the jaws. Patient was positioned so that the occlusal plane was parallel to the image S1.4 slice generated. Cotton rolls were inserted to separate the lips and cheeks from the gingiva. S1.5 Patient was informed to keep the tongue away from the palate (for maxilla). S1.6 The field of view is set to capture the entire arch. Scan settings used as recommended by V2R: Gantry tilt = 0 S1.7 Slice thickness 0.5mm Reconstructed slice increment = same as slice thickness Reconstruction of the images: S1.8 Images required: Axial slices only Format: DICOM (multi-slice format) Validation of the images prior to submitting to V2R All the markers are visible S1.9 The entire arch is visible No movement artifact detected