fundamentals of stereotaxy

8/11/2019 Fundamentals of Stereotaxy

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Fundamentals of Stereotaxy


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What is Stereotaxy?

Referencing of unknown volume within a coordinate system

Mathematical Concept that identifies a point in space by itsrelationship to 3 planes intersecting at right angles to each

other and intersecting at a common point


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X

Axes IntroducedFree Volume

X X

X

Imaging Grid

Quantifies Volume

Treatment Grid

Replaces Imaging Grid


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Axes Introduced

Free Volume

X

X

Imaging GridTreatment Grid

X

Headring = Axis

Localizer = GridCRW Arc = Treatment Grid

X


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Importance of Stereotaxy

Gives us the ability to reach very specific points in the

brain that are close to critical structures without creating

damage to surrounding tissue

Initial interest for Parkinsons Disease Surgery

Extended to applications where accuracy is paramount

biopsy

functional neurosurgery

microsurgery

radiosurgery


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History of Stereotaxy


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SPIEGEL WYCIS

Philadelphia, 1947

Human Stereotactic Apparatus

- tactic to touch


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Other Frames...

Lars Leksell, Sweden, 1949

Tallairach, Paris, France 1949

Riechert & Wolff, Freiburg, Germany 1951


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Problem with Existing Frames

No Quality Assurance

Stab blindly in the dark

?


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BRW

(Brown-Roberts-Wells)

USA, 1980

Interlocking Arcs

zero centred


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Quality Assurance

AP, LAT, VERT

BRW Phantom Base


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CRW

(Cosman-Roberts-Wells)

USA, 1988

Arc Centred

CRW Phantom Base


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Medical Imaging


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Role of Medical Imaging

Increasing interest for Cancer Treatment

Investigation

Diagnosis Planning

Monitoring Treatment of Malignant Diseases


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X-rays

Discovery of X-rays:

Wilhelm Rntgen, Wrzburg, Germany, November

1895

1st Clinical Use:

Needle removed from womans hand using X-rays

Birmingham, UK January 1896


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X-rays

X-rays:

Projectionof the

attenuating properties

of all the tissue along

the paths of photons

Patient

X-ray source

Receptor


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Angiography

X-ray of blood vessels

radio-opaque dye injected and x-rays taken


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Computerized Tomography

Conventional X-rays deficient in recognizing

Soft tissue

Depth Information

Needed Method for Taking X-rays on sections

of body


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Computerized Tomography

Invention: Radon, 1917

x-ray CT in Clinical Environment:

Hounsfield, British Institute of Radiology Conference,1972


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Magnetic Resonance Imaging

Nuclear Magnetic Resonance (NMR)

discovered independently by 2 sources in 1946

Resonance by Magnetic Field Gradient discovered in Lauterbur 1973

Put Patient in Magnetic Field & take images of

sections of body


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Apply Strong Magnetic Field


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Inject Pulsed Radiofrequency


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Remove Pulsed Radiofrequency


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CT vs MR

CT

Good for geometric accuracy

Bad for Morphological DetailMR

Good for Morphological Detail

Bad for geometric accuracy - distortion


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Other Types of Imaging

SPECT:

Single Photon Emission Computed Tomography

Allows us to see functional information on specific

organs. Inject radioactive isotopes that emit

gamma rays when decaying; these are shown in

the images


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fMRI:

functional Magnetic Resonance Imaging

Allows us to monitor increase of blood flow.

Different activity correspond to different levels of

blood flow. So, monitor the blood flow & you get

the different areas of brain controlling the various

functions.


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fMRI


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Image Guided Surgery

Horsley & Clarke

Spiegel & Wycis

Leksell

Tallairach

Riechert & Wolff

BRW

CRW

1908

1980s

Xray

CT

MR

PET/SPECT/fMRI

1876

1980sComputer Technology

Image

GuidedSurgery


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Horsley & Clarke

Spiegel & Wycis

Leksell

Tallairach

Riechert & Wolff

BRW

CRW

1908

1980s

Xray

CT

MR

PET/SPECT/fMRI

1876


3D Planning

Accurate Targetting

Reduce Damage to Healthy Tissue

More Procedures Operable

Patient Comfort


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Horsley & Clarke

Spiegel & Wycis

Leksell

Tallairach

Riechert & Wolff

BRW

CRW

1908

1980s

Xray

CT

MR

PET/SPECT/fMRI

1876



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Uses of Framed Stereotaxy

Stereotactic

Radiosurgery/Radiotherapy

Functional Neurosurgery


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Parkinsons isease Surgery


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Parkinsons isease Surgery


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Frameless Stereotaxy

Put CT/MR Scans of

Patient in w/sCo-register Patients

Head to Scans in w/s


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Markers Create Volume

in Image Space

Skin Markers

Localizer Quantifies Volume

in Image Space

Localizer


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Markers Create Volume

in Image Space

Skin MarkersRegister Patient to Image Space


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OAS

(Operating Arm System)

1992


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Surgical Product Range...

StereotaxyHardware/Software for

Frame Based StereotaxyNeurosurgery/Radiotherapy

Image GuidedHardware/Software for

Frameless Stereotaxy

fundamentals of stereotaxy

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