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©2016 V2R Biomedical Inc. V2R-PR-SP-V03
CT Scanning Protocol
For V2R® Guided Surgery Solutions
2 | V2R CT Scanning Protocol \\ Contents
©2016 V2R Biomedical Inc. V2R-PR-SP-V03
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
©2016 V2R Biomedical Inc. V2R-PR-SP-V03
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
©2016 V2R Biomedical Inc. V2R-PR-SP-V03
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
©2016 V2R Biomedical Inc. V2R-PR-SP-V03
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 elements1 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
©2016 V2R Biomedical Inc. V2R-PR-SP-V03
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.
o For an edentulous patient: Use the bite index to stabilize the scan appliance during the scanning procedure.
o 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 For an edentulous patient: Have the patient bite firmly on the bite index to stabilize the jaws.
o 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.)
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.
SCAN #1 Dentate
SCAN #1 Edentulous
7 | V2R CT Scanning Protocol \\ Dual Scan Protocol
©2016 V2R Biomedical Inc. V2R-PR-SP-V03
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.
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.
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.
Do not scan the bite index with the scan appliance.
SCAN #2 Dentate
SCAN #2 Edentulous
8 | V2R CT Scanning Protocol \\ Single Scan Protocol
©2016 V2R Biomedical Inc. V2R-PR-SP-V03
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
©2016 V2R Biomedical Inc. V2R-PR-SP-V03
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.
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.
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.
10 | V2R CT Scanning Protocol \\ Overview
©2016 V2R Biomedical Inc. V2R-PR-SP-V03
Overview
Dual Scan Protocol – Dentate patient
Dual Scan Protocol – Edentulous patient
Single Scan Protocol – DENTATE PATIENT ONLY (NOT RECOMMENDED)
SCAN #1
SCAN #1
Patient Scan appliance Cotton Rolls
SCAN #2
Scan appliance
SCAN #1
Patient Scan appliance Bite Index
SCAN #2
Scan appliance
Patient Cotton rolls
11 | V2R CT Scanning Protocol \\ Checklists
©2016 V2R Biomedical Inc. V2R-PR-SP-V03
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. ☐
S1.6 Patient was positioned so that the occlusal plane was parallel to the image slice generated.
☐
S1.7 Cotton rolls were inserted to separate the lips and cheeks from the gingiva. 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. ☐
S1.9
Scan settings used as recommended by V2R:
Gantry tilt = 0°
Slice thickness ≤ 0.5mm
Reconstructed slice increment = same as slice thickness
☐
S1.10
Reconstruction of the images:
Images required: Axial slices only
Format: .DICOM or .DCM, multi-slice
☐
S1.11
Validation of the images prior to submitting to V2R
All the markers are visible
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). ☐
S2.13 The scan appliance was positioned in the scanner in the same orientation 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. ☐
S2.15
Scan settings used as recommended by V2R:
Gantry tilt = 0°
Slice thickness ≤ 0.5mm
Reconstructed slice increment = same as slice thickness
☐
S2.16
Reconstruction of the images:
Images required: Axial slices only
Format: .DICOM or .DCM, multi-slice
☐
S2.17
Validation of the images prior to submitting to V2R:
All the markers are visible
The entire arch is visible
No movement artifact detected
☐
12 | V2R CT Scanning Protocol \\ Checklists
©2016 V2R Biomedical Inc. V2R-PR-SP-V03
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. ☐
S1.6 Patient was positioned so that the occlusal plane was parallel to the image slice generated.
☐
S1.7 Cotton rolls were inserted to separate the lips and cheeks from the gingiva. 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. ☐
S1.9
Scan settings used as recommended by V2R:
Gantry tilt = 0°
Slice thickness ≤ 0.5mm
Reconstructed slice increment = same as slice thickness
☐
S1.10
Reconstruction of the images:
Images required: Axial slices only
Format: .DICOM or .DCM, multi-slice ☐
S1.11
Validation of the images prior to submitting to V2R
All the markers are visible
The entire arch is visible
No movement artifact detected
☐
Scan #2 – Scan appliance assembled on the master model
S2.12 Scan appliance was adequately assembled to the master model. (The fit can be verified through the inspection windows).
☐
S2.13 The scan appliance (assembled on the master model) was positioned in the scanner in the same orientation it was when worn by the patient.
☐
S2.14 The field of view is set to capture the entire scan appliance and model assembly.
☐
S2.15
Scan settings used as recommended by V2R:
Gantry tilt = 0°
Slice thickness ≤ 0.5mm
Reconstructed slice increment = same as slice thickness
☐
S2.16
Reconstruction of the images:
Images required: Axial slices only
Format: .DICOM or .DCM, multi-slice
☐
S2.17
Validation of the images prior to submitting to V2R
The entire arch is visible
The occlusal anatomy is visible (patient not in intercuspation)
No movement artifact detected
☐
13 | V2R CT Scanning Protocol \\ Checklists
©2016 V2R Biomedical Inc. V2R-PR-SP-V03
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. ☐
S1.4 Patient was positioned so that the occlusal plane was parallel to the image slice generated.
☐
S1.5 Cotton rolls were inserted to separate the lips and cheeks from the gingiva. 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. ☐
S1.7
Scan settings used as recommended by V2R:
Gantry tilt = 0°
Slice thickness ≤ 0.5mm
Reconstructed slice increment = same as slice thickness
☐
S1.8
Reconstruction of the images:
Images required: Axial slices only
Format: DICOM (multi-slice format) ☐
S1.9
Validation of the images prior to submitting to V2R
All the markers are visible
The entire arch is visible
No movement artifact detected
☐
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