Medical Imaging

Mohammad Dawood

Department of Computer Science

University of MünsterGermany

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Medical Imaging, SS-2011

Mohammad Dawood

Recap

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Medical Imaging, SS-2011

Mohammad Dawood

X-Ray

CT

MRI

Larmor frequency

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Medical Imaging, SS-2011

Mohammad Dawood

Nuclear Medicine

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Medical Imaging, SS-2011

Mohammad Dawood

Nuclear medicine

Function not Density

Oncology/Cancer

Heart tissue viability

Brain dysfunctionepilepsystrokealzheimer

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Medical Imaging, SS-2011

Mohammad Dawood

Radioactivity

Bohr’s atomic model

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Medical Imaging, SS-2011

Mohammad Dawood

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Medical Imaging, SS-2011

Mohammad Dawood

Radioactivity

Isotopes

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Medical Imaging, SS-2011

Mohammad Dawood

Radioactivity

1. α decay

2. β- decay

3. β+ decay

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Medical Imaging, SS-2011

Mohammad Dawood

N

Z

Radioactivity

4. Electron capture

5. γ emission

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Medical Imaging, SS-2011

Mohammad Dawood

Radioactive penetration

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Medical Imaging, SS-2011

Mohammad Dawood

Radioactivity

Law of radioactive decay

Law of attenuation

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Medical Imaging, SS-2011

Mohammad Dawood

Isotop Half life4H 9.93696 × 10−23 Seconds26Na 1 Second15O 122 Seconds18F 110 Minutes131I 8 Days137Cs 30 Years239Pu 24.110 Years238U 4.468.000.000 Years232Th 14.050.000.000 Years

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Medical Imaging, SS-2011

Mohammad Dawood

Cyclotron

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Medical Imaging, SS-2011

Mohammad Dawood

Cyclotron

particles passing through the gap are accelerated

increase in velocity and mass result in spiral path

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Medical Imaging, SS-2011

Mohammad Dawood

Gamma Scintigraphy

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Medical Imaging, SS-2011

Mohammad Dawood

Scintigraphy

gamma emitters

99Mo → 99mTc + β⁻ + νe

99mTc → 99Tc + γ

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Medical Imaging, SS-2011

Mohammad Dawood

Gamma camera

principle of anger camera

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Medical Imaging, SS-2011

Mohammad Dawood

Collimator

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Medical Imaging, SS-2011

Mohammad Dawood

Scintillators

Organic crystals, Organic liquidsAnorganic crystals, Plastic

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Medical Imaging, SS-2011

Mohammad Dawood

Photomultiplier tube

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Medical Imaging, SS-2011

Mohammad Dawood

SPECT(Single Photon Emission Computed Tomography)

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Medical Imaging, SS-2011

Mohammad Dawood

SPECT camera

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Medical Imaging, SS-2011

Mohammad Dawood

SPECT camera

Multiple angles

3-6 degrees

ca 15-20 sec per angle

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Medical Imaging, SS-2011

Mohammad Dawood

SPECT camera

Pinhole SPECT

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Medical Imaging, SS-2011

Mohammad Dawood

PET(Positron Emission Tomography)

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Medical Imaging, SS-2011

Mohammad Dawood

β+-decay

Positron (e+)

Neutrino (ν)

Electron (e-)

Annihilation

p → n + e+ + e+ + e- → 2

Eγ = 511 keVAngle = 180°

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Medical Imaging, SS-2011

Mohammad Dawood

Coincidence Unit

Sorting Unit

ImageReconstruction

PET Image

Detectors

Decay

Millions of events are detected during few minutes of PET scan

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Medical Imaging, SS-2011

Mohammad Dawood

PET

Detectors

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Medical Imaging, SS-2011

Mohammad Dawood

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Medical Imaging, SS-2011

Mohammad Dawood

X

y

X1

y13),( 11 yxI

PETProjections

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Medical Imaging, SS-2011

Mohammad Dawood

s

)(sI

PETProjections

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Medical Imaging, SS-2011

Mohammad Dawood

PETProjections from different angels

s

),( tI

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Medical Imaging, SS-2011

Mohammad Dawood

t

)(0 sP

t

0

PETProjections from different angels

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Medical Imaging, SS-2011

Mohammad Dawood

s

45o

PETProjections from different angels

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Medical Imaging, SS-2011

Mohammad Dawood

s

90o

PETProjections from different angels

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Medical Imaging, SS-2011

Mohammad Dawood

PET

Projection sinogram

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Medical Imaging, SS-2011

Mohammad Dawood

PET

Positron range

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Medical Imaging, SS-2011

Mohammad Dawood

PET

Non-colinearity

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Medical Imaging, SS-2011

Mohammad Dawood

PET

Arc correction

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Medical Imaging, SS-2011

Mohammad Dawood

PET

Geometric sensitivity is inhomogeneous

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Medical Imaging, SS-2011

Mohammad Dawood

PET

Crystal efficiency normalization

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Medical Imaging, SS-2011

Mohammad Dawood

PET

Random and Scatter

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Medical Imaging, SS-2011

Mohammad Dawood

PET

Scatter

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Medical Imaging, SS-2011

Mohammad Dawood

Coincidence Unit

Sorting Unit

ImageReconstruction

Decay

Time of flight PET