PET

                                         

PET- POSITRON EMISSION TOMOGRAPHY

• NONINVASIVE NUCLEAR IMAGING TECHNIQUE THAT INVOLVES THE ADMINISTRATION OF A RADIOPHARMACEUTICAL AND SUBSEQUENT IMAGING OF THE DISTRIBUTION AND KINETICS OF THE RADIOACTIVE MATERIAL.

PET IS A PHYSIOLOGIC MODALITY

• IS PREDOMINANTLY USED TO MEASURE HUMAN CELLULAR, ORGAN, OR SYSTEM FUNCTION.

PHYSIOLOGIC ASPECT OF THE TISSUE UNDER STUDY

• IS DETERMINED FROM THE MEASUREMENT OF THE RADIOACTIVITY EMITTED BY A RADIOPHARMACEUTICAL IN THAT TISSUE.

POSITRON EMITTING RADIONUCLIDES

• 11C - CARBON

• 13N - NITROGEN

• 15O - OXYGEN

• 18F – FLUORINE

HISTORY OF PET

• THE USE OF POSITRON EMITTING RADIOPHARMACEUTICALS FOR MEDICAL PURPOSE WAS FIRST CONCEIVED IN THE EARLY 1930s BY E.O. LAWRENCE- THE INVENTOR OF CYCLOTRON.

E.O. LAWRENCE

COMPOUNDS WITH POSITRON EMITTING REDIONUCLIDES WERE

SYNTHESIZED AND GEIGER COUNTERS WOULD BE USED TO MEASURE THE

UPTAKE OF RADIONUCLIDE BY DIFFERENT BODY PARTS.

F.W. WRENN SHOWED THE USE OF POSITRON EMITTING RADIONUCLIDES

FOR LOCALIZATION OF BRAIN TUMORS IN 1951.

IN 1967 G. HOUNSFIELD DEMONSTRATED THE CLINICAL USE OF CT. THE MATHEMATICS OF IMAGE

RECONSTRUCTION AND PET ARE SIMILAR.

IN 1975 THE FIRST CLOSED- RING TRANSVERSE POSITRON TOMOGRAPH WAS BUILTFOR PET IMAGING BY M.M.

TER-POGOSSIAN.

SINCE 1975:

• BETTER RESOLUTION IN PET IS BEING ACHIEVED NEARING 1-2 MM

• NEW RADIOPHARMACEUTICAL AGENTS ARE BEING DEVELOPED TO STUDY: BLOOD FLOW, METABOLISM, PROTEIN SYNTHESIS, LIPID CONTET, RECEPTOR BINDING AND MANY OTHER.

DETECTOR TYPES: SCINTILLATION- BETTER

RESOLUTION

PM TUBE

S. CRYSTALS. CRYSTAL

PHOTODIODE

POSITRON

•Atomic particle with properties identical to those of a negatively charged electron, except for its positive charge. The positron is the antiparticle of the electron. Positrons and electrons annihilate one another when they meet, producing pure energy in the form of gamma rays

PET

• PAIR PRODUCTION INTERACTION IS UTILIZED!!

Pair Production (PP) can occur when the x-ray photon energy is greater than 1.02 MeV, when an electron and positron are created with the annihilation of the x-ray photon. Positrons are

very short lived and disappear (positron annihilation) with the formation of two photons

of 0.51 MeV energy. Pair production is of particular importance when high-energy photons pass through materials of a high atomic number.

Energy: > 1.02 MeV

When we talk about the beta plus decay a proton decays into a neutron, a positron (the antiparticle of the electron) and a neutrino. The positron and the neutrino are emited. The radioactive particle is the positron

                                                                        

DATA ACQUSITION IN:

• CT

• MRI

• PET

CT

MRI

PET800 DETECTORS

RESOLUTION OF IMAGES

• CT –512 X 512

• MRI 512 X 512

• PET – 64 X 64

COMPARISON

PRODUCTION OF POSITRON EMITTERS

• CYCLOTRON METHOD

• MILKING OF RADIONUCLIDE GENERATOR

CYCLOTRON

BOMBARDMENT OF STABLE NUCLEI WITH HIGH ENERGY BEAMS OF

CHARGED PARTICLES.

MILKING OF RADIONUCLIDE GENERATOR

PET SCANNER

GANTRY AND DETECTORS

CLINICAL APPLICATIONSBRAIN:

• DEMENTIAS

• COMPLEX PARTIAL EPILEPSY

• STROKE

• TUMORS

DEMENTIAS- ALZHEIMER’S DISEASE

BILATERAL HYPOMETABOLISM APPEARS IN PARIETAL AND TEMPORAL ASSOCIATION AREAS

EPILEPSY

SHOW FOCI

STROKE

METASTATIC TUMOR

CLINICAL APPLICATION OF PET

HEART

• CORONARY ARTERY DISEASE

CAD

FUSION OF PET AND CT

FUSION OF PET AND CT