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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


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 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.



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



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;


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


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.


Recommended scan settings*

Gantry tilt: None (0°)

Slice thickness: ≤ 0.5mm

Reconstructed slice increment: Same value as slice thickness

Recommended image reconstruction settings*


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


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


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:


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


Gantry tilt = 0°



☐

S2.16




☐

S2.17

Validation of the images prior to submitting to V2R:




☐



DUAL SCAN PROTOCOL – DENTATE PATIENT


Scan #1 – Patient + Scan appliance


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. ☐



☐


☐

S1.8 The field of view is set to capture the relevant anatomy and markers. ☐

S1.9


Gantry tilt = 0°



☐

S1.10



Format: .DICOM or .DCM, multi-slice ☐

S1.11





☐

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


Gantry tilt = 0°



☐

S2.16




☐

S2.17



The occlusal anatomy is visible (patient not in intercuspation)


☐



SINGLE SCAN PROTOCOL – DENTATE PATIENT ONLY – *NOT RECOMMENDED*


Scan #1 – Patient + Scan appliance



S2.3 Cotton rolls were added to stabilize and separate the jaws. ☐


☐


☐

S1.6 The field of view is set to capture the entire arch. ☐

S1.7


Gantry tilt = 0°



☐

S1.8



Format: DICOM (multi-slice format) ☐

S1.9





☐

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