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Cone Beam CT

An alternative approach to extremity imaging?

Peter Sharpe Roisin Dobbin-Stacey

Chief Executive PET/CT – CT Manager

Medical charity

Providing MRI , PET/CT, CBCT & DXR

65,000 patients annually

Research – Fund and participate

Provide - Training & education.

Cobalt – Who are we?

Objectives – to innovate

First:

1.5T Mobile MRI

High-field Open MRI

Open PET/CT

3.0T Mobile MRI

ISAS accreditation

Wide bore digital mobile MRI

Flow PET/CT technology

Carestream - MyVue & VueMotion.

Cobalt – Who are we?

Why CBCT for Cobalt?

Good fit – Innovation and research

Good partnership with Carestream

Very positive reviews from a range of international ‘trade sites’

One stop orthopaedic clinics – DXR weight bearing

Research opportunity.

What is Cone Beam CT Traditional CT

Cone Beam CT

A narrow slice of the patient is imaged

with a fan-beam of x-rays and multiple

rotations; z direction typically has

lower resolution

A large-area flat panel detector images

an extended volume of the patient in a

single rotation; same (isotropic)

resolution in all 3 directions

What is Cone Beam CT

Single

Source

3 Source

Increases reconstruction volume by ~50%

Reduces “cone beam” artifact

Enables future advanced acquisition

protocols

o Dual energy

Why did Carestream develop CBCT?

OnSight Extremity CBCT

Designed specifically for imaging of extremities

Hand, wrist, elbow, knee, ankle, foot

Benefits

Weight bearing imaging for knee / foot / ankle

Comfort features - low dose

Improved visualization over 2D or standard 3D imaging

o Isotropic resolution

o Advanced Iterative image reconstruction

o Good soft tissue visualization

o Advanced Scatter and Metal Artifact Reduction

Large field of view – 21cm x 22cm

Compact design and reduced shielding requirements – Low cost

Fraction of MDCT cost

Imaging right at the point of care - faster diagnosis and treatment

Installation - Requirements

Small system and footprint

Standard ceiling height

Room shielding typically not

required*

*consult local regulations

Installation

Room pre-installation and post installation

OnSight Extremity CBCT

Designed to provide the lowest level of patient

and operator exposure

Patient exposure is reduced - compared to

traditional Multi-Detector CT

Only exposes joint under examination

Minimises scattered radiation - integrated lead

curtain and well shielded

OnSight Extremity CBCT – Bore volume

Large

field of view

Reconstruction volume

Bore opening

Applications

Motorised movements - auto-positions

for height, tilt and rotation

Stepstool and positioning guides

Patient monitor for imaging status

Patient support handles

Touch-screen monitor - intuitive user

interface

Specific patient chair

Applications

One stop orthopaedic clinics

DXR weight bearing studies

Demand for MDCT increasing

Ease of access

Applications

Potential to replace DXR and MDCT

More diagnostic confidence - Rreduction in repeat examinations

Occult and non-displaced fractures

Scaphoid fracture detection and healing evaluation

Non-unions and growth plate fractures in children, follow-up / fusion healing

Impingement (under load)

Evaluation of disease progression, for RA , OA and Gout

Post operative and follow up joint replacement

Design joint replacement

Initial Experience – Hand & Wrist

• 3D weight-bearing

• Accurate determination of the relative placement and

orientation of the bones while under realistic load

conditions

Investigational: Not Available for Commercial Sale

• Fracture Trapezium and

distal radius

Hand and Wrist

Initial Experience – Foot and Ankle

3D weight-bearing

Accurate determination of the relative placement and

orientation of the bones while under realistic load

conditions

Investigational: Not Available for Commercial Sale

Large Field of View Image the Tripod of the foot

Weight–Bearing 3D Exams - Ankle

Sc

Weight–Bearing 3D Exams - Ankle

Non weight-bearing Weight-bearing Non weight-bearing Weight-bearing

Investigational: Not Available for Commercial Sale

? Impingement MRI vs CBCT & DXR

Investigational: Not Available for Commercial Sale

Impingement

Investigational: Not Available for Commercial Sale

Ankle MRI vs. CBCT & DXR – Posterior impingement

Investigational: Not Available for Commercial Sale

Ankle – post surgery ? union

Investigational: Not Available for Commercial Sale

Trauma – Metal Artifact Reduction

Initial Experience – Knee

Investigational: Not Available for Commercial Sale

Knee - OA

Investigational: Not Available for Commercial Sale

Knee post KR fracture or loose component

Investigational: Not Available for Commercial Sale

3D surface rendering

Effective Dose

References:

Assessment of Effective Radiation Dose od An Extremity CBCT, MDCT and Conventional X-Ray for Knee

Using Mosfet Dosimeters – Juha Kivisto et al Department of Physics, University of Helsinki, Finland., 2013

Imaging of the knee

Modality Effective Dose

MDCT 27 - 48µSv.

CBCT 12.6µSv.

DXR (4 view) 6.0µSv.

Effective Dose

Modality Effective Dose

Chest MDCT ~7000 µSv (1,2)

Head MDCT ~2000 µSv (1)

Extremity MDCT ~30 to 160 µSv depending on anatomy and study details (4)

Chest radiograph ~20 to 100 µSv depending on study details (3)

OnSight CBCT Extremity scan ~5 to 40 µSv depending on anatomy and study details

2D Radiographic study of an extremity ~0.2 to 3 µSv depending on anatomy and study details (3)

1 day natural background exposure ~17 µSv (1)

1 trans-continental flight from NY to LA ~25 µSv (5)

References:

(1) www.epa.gov/radiation/radiation-sources-and-doses

(2) McCollough et.al. “Answers to common questions about the use and safety of

CT scans.” Mayo Clin Proc. (2015) 90(10):1380-92

(3) Huda W. et.al. “Radiation Dosimetry for Extremity Radiographs” Health Physics

(1998) 75(5):492-499

(4) Biswas et.al. “Radiation Exposure from Musculoskeletal Computerized

Tomographic Scans” J. Bone Joint Surg. Am. (2009) 91:1882-9

(5) http://jag.cami.jccbi.gov/cariprofile.asp

Conclusion

Initial experience positive

User friendly

Adoption rate typical

Higher resolution images than MDCT and DXR*

Lower dose than MDCT

Quicker than MDCT and DXR*

Good patient acceptance - Weight bearing

Metal Artefact Reduction – Works well

Competes with MDCT – Compliments DXR.

*Using Cone Beam CT as a low-does 3D imaging technique for extremities: initial experience in 50 subjects

Skeletal Radiology June 2015 Huang AJ, Chang CY Thomas BJ;

Future – Research Project

CBCT with MAR - Assessment of total knee replacement

Potential to deliver high image data with quantifiable

measurement of 3D position, fixation and bone density

Replacing 2D radiographs

Post surgery – assess position , exclude any bone damage

Early years – loosening, infection

End of life- loosening, bone loss, fractures in bone or metal

work

Results – better pre-op assessment, possible personalised

prediction of implant survival.