Principles of Cone Beam Volumetric Tomography

Planmeca ProMax 3D ModelsPlanmeca ProMax 3D family offers a solution for the most demanding imaging needs, producing various imaging sizes with one concept an ideal imaging size for different maxillofacial applications.

Extended applicationsUnique new imaging capabilities for: Implant planningOral surgeryImpacted teeth3rd molar extractionsOcclusion analysisTMJ analysisPeriodonticsAirway studies

Emerging new diagnostic applications

3D technologyCBCT - Cone Beam Computed Tomography

CBVT - Cone Beam Volumetric Tomography

DVT Digital Volume Tomography

A technological advance from traditional CAT Scan, medical CT or fan beam CT

Medical CT

Medical CT vs CBVTX-ray sourceobjectLine detectorMovement of translation and axis of rotationX-ray sourceobjectaxis of rotationFlat panel detector

CBCT volume capture

CBCT volume captureZYX

Medical CT vs. CBVTMedical CT: Slices are acquired then reconstructed to create the volume

Medical CT vs. CBVTCBCT:The volume is acquired then slices are reconstructed from the volume

ProMax 3D technologyStroboscopic effect, images taken using short X-ray pulses during the scan300/450 images taken during the scanCumulative exposure time 2.8 -12 sec for 18 sec scanEnhanced clarity of the imagesReduced radiation dose

ProMax 3D Max & Mid ScanningSymmetric scanningC-arm rotatesMagnification 1.8xScan angle 200 deg300 framesMax. volume 100 x 130 mmAsymmetric off-set scanningElbow arm rotatesMagnification 1.44xScan angle 360 deg450 framesMax. volume 230 x 160 mm

Asymmetric off-set scanningSensor shift changes the acquisition geometry and reduces the final image qualityThe shift of whole c-arm remains the acquisition geometry constant and produces better final image

Back projection basic images

Back projection

ProMax 3D Technology 3D image volume is a cylinderCylinder consists of more than 120 million voxelsVoxel size 0.1 x 0.1 x 0.1 mm, 0.2 x 0.2 x 0.2 mm, 0.4 x 0.4 x 0.4 mm or 0.6 x 0.6 x 0.6 mm

Isotropic voxelCBVT has always an isotropic voxelThe reconstruction can produce any size of voxelThe voxel is always perfect cubeThe measurements are exactVoxel size is typically 0.1 0.5 mm

CT has an anisotropic voxelThe voxel is always a brickThe pitch (= distance between spiral rounds = layer thickness) varies and causes distortion in the 3D measurements.The layer thickness is typically 0.5 0.8 mm

Pulsed X-rayPulsed X-ray produces sharp images with less dose.

3D Technology Flat PanelPlanmeca ProMax 3D flat panel imaging chainConventional imaging chain with Image IntensifierX-ray Tube Patient Image Intensifier TV Camera Digital ImageX-ray Tube Patient Flat Panel - Digital ImageModern Flat Panel Technology for maximum performance

Image intensifier

3D Technology Flat PanelImage intensifier has both distortion and brightness non-uniformity which is absent from the flat panel detectorImage intensifier needs periodical maintenance. It has limited life span 3-6 years.It is sensitive to magnetic or electrical fields.It is over 60 years old technology.

3D technology Tube Current ModulationDifferent attenuation properties across and along the patient's headTube current (mAs) can be dynamically adjustedReduces patient dose and improves image quality

Comparison

PlanmecaProMax 3D sPlanmeca ProMax 3D Planmeca ProMax 3D MidPlanmeca ProMax 3D MaxVoxel size100 / 200 m *100 / 200 / 400 m100 / 200 / 400 / 600 m100 / 200 / 400 / 600 mMax. 3D volume (diam. x height )50 x 80 mm80 x 80 mm160 x 90 mm230 x 160 mmMax. 3D volume withstitching, (diam. x height)90 x 130 mm150 x 130 mm160 x 160 mm230 x 260 mmStitching, verticalYesYesYesYesStitching, horizontalYesYesNoNoSmartPan imagingYesYesYesNoDimax Panoramic imagingOptionalOptionalOptionalNoDimax CephalostatOptionalOptionalOptionalNoMotorised patient supportfor vertical movementNoNoYesYes

CBCT vs. Medical CTCone Beam Imaging is:FasterSmallerSafer (lower dose)Less expensiveMore convenientDentally specificHigher resolutionBetter image quality

WHAT ARE THE DOSES?

Radiation dose International Commision on Radiological Protection, Standards for absorbed dose from 1990 and 2007

Radiation dose Medical CT 1200-3300 SvDr Stuart White, UCLADig. Pan ca 7 SvFMS 90 uSvDr Sharon Brooks, O of Michigan, ICRP 1990

Dig. Pan 6,7 SvFMS 84 uSvDr Stuart White 1992, ICRP 1990

Typical panoramic dose 24.5 SvDr Ludlow, ICRP 2007

Radiation doseThe estimated effective patient dose, Planmeca ProMax 3D software version 1.21.4, Dr. Mika Kortesniemi:Radiation dose of CBCT 20- 250 SvSame level as 2-10 panoramic imagesSame level as full mouth series with film Essentially lower than medical CT

IMAGING PROTOCOLHigh and Normal Resolution modesLow Dose modeIMAGING OBJECTLeft 3rd molarLeft 3rd molarFOV [d cm x h cm]8 x 88 x 8TUBE VOLTAGE [kV]8484TUBE CURRENT [mA]128EXPOSURETIME [s]122.8CURRENT TIME PRODUCT [mAs]14422.4CURRENT TIME PROFILE [MIN(mAs) / MAX(mAs)]1.00.3Effective dose [mSv] (ICRP 1990)0.1220.021Effective dose [mSv] (ICRP 2007)0.2520.045

Dose Radon, background, smoking US Study: Average yearly dose of 2070 Sv from radonAverage yearly dose of 320 Sv from smokingAverage yearly dose of 4000 Sv from background radiation in Denmark

Dose Flight www.gsf.de/epcard

Dose Risks ec.europa.eu/energy/nuclear/radioprotection/publication/doc/136_en.pdfAge:

The EndMore information:Erkki HiltunenProduct Manager, X-raystel: +358 20 7795 456 erkki.hiltunen@planmeca.com

Mark NiemiProduct Manager, X-raystel: +358 20 7795 743 mark.niemi@planmeca.com

More information:Osku SundqvistProduct Manager, Softwaretel: +358 20 7795 793osku.sundqvist@planmeca.com4/2011

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