medical application of emf
Post on 16-Jul-2015
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M.KUMARASAMY COLLEGE OF
ENGINEERING
WELCOME
2/15/2015 EMF 1
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What do Physicists do in…
“REAL LIFE
Many work with doctors
in the field of
Medicine
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Doctors often need to look inside our
bodies without cutting them open….
Some you may have heard of…
X-rays…..NMR…..MRI scans
And new ones you may not have heard of yet….
PET scans…..MEG
are essential in the development of many scanning technologies
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Here is your chance
to…Find out the basics of how these
scans work
See how important electro magnetic
field in modern medicine.
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ELECTRO
MAGNETICWAVES
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X-
raysVery little ordinary
light can pass
through skin. It’s
either absorbed at
the surface or
reflected back..
To “see” inside we
need a kind of
“light” with more
energy…
Skin
Ordinary Light
X rays
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Taking “X rays”
The patient is
placed in
front of a
source of
X-rays.
X ray
Tube
A photo graphic
plate is placed
on the other
side of the
patient
Most of the
X rays pass
through the
patient’s
body…….
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X-rays are also partly absorbed by some
tissues in body this creates a more subtle
picture.
SOFT
TISSUE
bone
Soft tissue
Photographic
plate
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X-RAYS
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Advantage of X rays
X-rays are easy to produce
X-rays machines are relatively cheap
X-rays are used to diagnose broken
bones, dislocated joints etc..
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Disadvantage of X-rays
In large doses X rays can
harmful to health.
Imaging of soft tissues and
organs is not always very
detailed.
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MRIWhat do the letters stand
for?
M……….. Magnetic
R………… Resonance
I…………. Imaging
MRI scanners do not use X rays.
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With the patient safety check
complete the scan can
begin…The part of the body to be scanned is placed in the centre of the primary magnet
X
This field causes the Hydrogen nuclei in the
patients body to line up with the field2/15/2015 14
The patient is placed on a bed and then
moved into a large hollow tube.
The tube contains a very powerful
magnet….
Using an MRI
Scanner…
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It took physicists over 40 years to turn their
discovery of nuclear magnets into images of
the human body.
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View an MRI scan from any
angle..
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ADVANTAGES
Do not involve
exposure to
radiations.
Ability to image
without the use of
ionising radiations.
Scanning and
detection of
abnormalities in soft
tissues.2/15/2015 18
DISADVANTAGES
Very expensive (1 million )
While processing creates
so much of noise.
It is done in enclosed
space.
Less spatial resolution than
COMPUTED
TOMOGRAPHY.
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PET(positron emission tomography)
“snapshot” images are useful
but doctors sometimes need “real time”pictures of how parts of your body are
functioning…
e.g. How your heart is
functioning.
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PET SCANNERS LOOK LIKE CT
SCANNERS…
-NO X RAY
TUBE.
-The ring is
surrounded by
“Gamma Ray”
detectors
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PET scan patients are injected with a
specially created substance called a
“RADIOTRACER”….
Usually a “Radioactive” type
of glucose.
The radiotracer is a
source of positrons
which leads to the
production of gamma
rays…
INSIDE THE PATIENTS
BODY!
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The radiotracer concentrates itself
in certain tissue types…
This glucose type
radiotracer has
concentrated
itself in high
glucose using
cells like the
brain, kidneys
and cancer cells.
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PET ScansThe biggest cost
is in the
production of
RADIOTRACE
R
The hospital
needs to have
access to a
“CYCLOTRON
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ADVANTAGES
Used for diagnosis of
many diseases.
At small movement it
does not ruin the scan.
To show blood flow,
oxygen and glucose
metabolism in the
tissue.
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DISADVANTAGES
Scans works by
injecting a patient with
radionuclide.
Radioactivity decays
rapidly.
Images are of
substantially lower.
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MEG(magnetoencephalography)
It doesn’t put anything
into a patients body….
It just measures something that is
already there
No X rays/Strong Magnetic
Fields/Radio
waves/Radiotracers
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Your body is full of tiny electric
currents!
These tiny currents produce tiny magnetic
fields
MEG is able to measure some of these.2/15/201528
ADVANTAGES
Measure activity of the
brain extreme quickly.
Temporal specificity
Effective diagnostic tool
for evaluating brain
function.
Easy to use
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DISADVANTAGES
Very invasive
More expensive
Cannot detect activity of
the cell
Cannot be used with the
patients who are
claustrophobic.
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NMR(NUCLEAR MAGNETIC RESONANCE)
Used for magnetic resonance
imaging for medical diagnosis and
magnetic resonance microscopy in
research setting.
Biochemical information can also be
achieved from LIVING TISSUE.
EX: HUMAN BRAIN TUMOR
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NMR process
NMR scan the narrow table moves the patient through a tunnel like structure
create a magnetic field through which radio waves are sent , creating a 3-D image of the internal structure.
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NMR SCANNER
NMR SCANNER
also utilised
in low field NMR.
Its effectiveness can be
Improved byHYPERPOLARISATION
and using 2D,3D
Techniques.
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NMR HAHN ECHO DECAY
EXPERIMENT
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ADVANTAGES
Does not require contrast media,so no
anaphy lactic reaction.
Better accuracy in localisation of
etiology
No complications like
pancreatitis,bleeding etc..
Non invasive
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DISADVANTAGES
Imaging compared with other
modalities is intrinsic
insesitivity of the method.
Very expensive
Time consuming
Spectra take long time to
interpret.
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ELECTRO MAGNETIC BLOOD
FLOW METERWorks on the principle of
FARADAY’S LAW OF
ELECTRO MAGNETIC
INDUCTION’.
Used to measure the blood
flow
For this the diameter of
blood vessel is outlined by
the TRANSDUCER IN THE
RADIOGRAM2/15/2015 EMF 37
ELECTRO MAGNETIC BLOOD
FLOW METER
It is used during the
vascular surgery to
measure the quantity
of blood passing
through the vessel or
graft before during or
after surgery.
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VARIOUS METHODS USED FOR
ASSESSMENT
Observation and
palpation of pulses
Intra-arterial pressure
measurements with
careful attention to the
presence of
“GRADIENTS’
Arteriography
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ADVANTAGES
Measurement of flow and
volume of blood.
During arterial
reconstruction
Superior mesenteric artery
reconstruction
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DISADVANTAGES
Some times magnetic fields
are not uniform
Wall of flow tube is
conductive
Flow is axially non-
symmetrical
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THANK YOU
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QUERIES….?
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