pet scan.ppt

PET SCAN
PRESENTATION BY:- GAURAV DAREKAR
GUIDE BY :-NISHA MAM

PET
[ POSITRON EMISSION TOMOGRAPHY ]

CONTENT
• INTRODUCTION
• HISTORY
• PRINCIPLE
• COMPONENT
• APPLICATION

INTRODUCTION
• PET also called PET imaging or a PET scan.
• PET scan is a type of nuclear medicine
imaging
• PET Machine that can image biological and
chemical activities

• PET scan gives physiological function of the
body.
• PET scanner is used produce an image
showing the distribution of the tracer in the
body.
• PET is an imaging madality that produces 3 D
images of the body that are capable of
demonstrations the biochemical function of
bodys organs and tissues.

HISTORY
• 1975 the first commercial PET scanner was
introduced.
• 70s and 80s PET was mainly used for research.
• 1990s being used in clinics regularly.

PRINCIPAL
•PET is uses radiotracer or pharmaceutical
fluoro deoxy- glucose (FDG).
•Firstly, FDG is injected intravenously into the
patient.
•FDG emits positron by going into the
patient’s abnormalities or malignancy tissue.

• The half-life of positron is very short.
• metabolism
• Glucose molecules-------- Glucose-6
Phosphate.
• FDG is similar to our glucose molecule
and travels in the body same way as
glucose and undergoes metabolism
• metabolism
• FDG ------------- FDG-6 Phosphate
• (Hexokinase)

• It the tissue is normal, this process continues
during the metabolism.
• If there is any malignancy, presence of
pathology, infection and other abnormality, the
FDG gets trapped.
• FDG emits Positron from abnormal tissue.
• The emitted positron joints with an electron
and undergoes annihilation.

• The positron
annihilation
produces 2
photons of
energy 511 keV
each emitted in
opposite direc -
tion (180°) in the
body site.

• These photons
detected by a set of
ring detectors
surroundings the
patient .
• The detector sends
these signals to the
computer and the
computer creates the
final image from
thesesignals.

COMPONENTS OF PET SCAN
• Scanner gantry
• A. Detector
• B. Septa
• C. Coincidence circuit
• 2. Table
• 3. Computer
• 4. Cyclotron

1. PET GANTRY
• Shape = Round donut shape
• Diameter = 70-80 cm
• A. Detector
• B. Septa
• C. Coincidence circuit

A. DETECTOR
• PET equipment consist of a ring of detector
surrounding the patient.
• Scintillation crystal (10000-20000) are used as
detectors, e.g. – bismuth germanate (BGO),
lutetium oxyortho- -silicate (LSO), and gadolinium oxy-
-orthosilicate(GSO)

4 photo multiplier tubes
arranged in a circular pattern
around the patient.
 Generally, detectors must
have high detection
efficiency, less afterglow and
energy resolution.
 Detectors are made in block
format coupled with photo- -
multiplier tubes (PMT).

• The PET detectors detect the emission
photons and convert them into light
signals.
• This scintillation event is converted into
an electric signal by PMT, which can be
displayed on a monitor.

B. SEPTA
• Lead of tungsten circular shield mounted between the detector rin
• Limits scattered radiation from the object reaching the detector.

C. COINCIDENCE DETECTION
• Annihilation coincidence detection circuits,
detects co- -incidence interaction with in
each pair of detectors and obtain line of
response (LOR)
• The effective attenuation suffered by the
two Photons is determined

• The time of flight (TOF) of the photons are also
detected
• The coincidence may be :-
• 1.True coincidence
•
• 2. Random coincidence
•
• 3. Scatter coincidence
•
• 4.Multiple coincidence

A true coincidence arises from a single event, in the
same plane.
The scattred coincidence is due to single event, but in different
plane, due to scatter.

The random coincidence is due to two independent events,
not in the same plane.
Multiple coincidence is the detection of two independent events
that are detected at the same time.

2.TABLE
• The bed is capable of moving in and out of the scanner to
measure the distribution of PET radio pharmaceuti- -cals
through out the body, and it adjusts to a very low position
for easy patient access.

3. COMPUTER
• A computer analyzes the gamma rays and uses the
information to create an image map of the orgen
or tissue being studied.
• In 3D image reconstruction algorithm is used.

4. CYCLOTRON
• The high energy particles produced in a cyclotron
are used to bombard nuclei and study the resulting
nuclear reactions and hence investigate nuclear
structure.
• A machine used to produce the radioisotopes
(radio - -active chemical elements) which are
used to synthesize the radio pharmaceuticals

APPLICATION OF PET SCAN
• Detect cancer.
• Determine whether a cancer has spread in the body.
• Determine if a cancer has returned after treatment.
• Determine blood flow to the heart muscle.
• Determine the effects of a heart attack, or myocardial infarction
on areas of the heart.

CONTINUE
• Evaluate brain abnormalities, such as tumors,
memory disorders and seizures and other central
nervous system disorders.
• To map normal human brain and heart function.

pet scan.ppt

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