ENU 6659 Intro

Nuclear Medicine

Imaging of (injected) radio-labeled pharmaceuticals

Emission Tomography

3D nuclear medicine imaging

• SPECT: single photon emission computed tomography

• PET: positron emission tomography

# PET systems / pop. # PET systems / pop. millionmillion

0

1

2

3

4

5

6

7

8

9

CA TX NY FL IL PA OH MI GA NJ NC

IMV 2005/2006 Market Summary ReportIMV 2005/2006 Market Summary Report

•Bone scan

•Tc-99m

•anterior/posterior views

Nuclear medicine (PET and SPECT) provides images related to the body’s

Function (physiology)

compared with x-ray images that are related to the body’s

Anatomy (physical properties)

Brain metabolism imaging w/ PET

Normal

Perfusiondefect

Myocardial Perfusion Imaging w/ SPECT

PET Brain ImagesPET Brain Images

Alzheimer’s Disease with Alzheimer’s Disease with PETPET

normal

diseased

Molecular Imaging

moles / min / ml of tissue

F-18 Fluoro-deoxy-glucose F-18 Fluoro-deoxy-glucose (FDG)(FDG)

(PET metabolism tracer)(PET metabolism tracer)

Advances in SPECT gamma camerasAdvances in SPECT gamma cameras

1980 1985 1990

dual head (fixed 180)

single head triple head (fixed 120)

1990 1995 2000

Advances in SPECT gamma camerasAdvances in SPECT gamma cameras

dual head (fixed 90)

dual head (variable angle)

triple head (variable angle)

SPECT InstrumentationSPECT Instrumentation

transmission

emission

No collimator

transmission

emission

With collimator

Annihilation Annihilation (simple)(simple)

conservation of momentum:

before: system at rest; momentum ~ 0

after: two photons created; must have same energy and travel in opposite direction.

conservation of energy

before: 2 electrons, each with a rest mass of 511keV

after: 2 photons, each with 511keV.

decay via positronemission

electron/positronannihilation

annihilationphoton

annihilationphoton

PET PhysicsPET Physics

Coincidence EventCoincidence Event

Annihilation location

Time-of-Flight PETTime-of-Flight PET

Annihilation location

d1

d2

t = (d2-d1)/c

t

x = t·c/2

Detector midpointx

= 2x/c

PET InstrumentationPET Instrumentation

PET/CTPET/CT

PET

PET/CT

ET Detectors (i.e. Cameras)ET Detectors (i.e. Cameras)

Needs: High count rate capability (short T1/2 emitters)

Efficiency (511 keV) Energy resolution (scatter rejection)

Low cost

Detector MaterialsDetector Materials

Scintillators• NaI• BGO• LSO

Semiconductors• CdZnTe

Cardiac perfusion imaging:Cardiac perfusion imaging: Attenuation effectsAttenuation effects

Without attenuation correctionWith attenuation correction