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UNIT 21 A and B
- Module
- (UNIT21AB)
- Institution
- PEARSON (PEARSON)
i got distinction, its about ionizing and non ionising techniques
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,Non-ionising techniquesMagnets-
Hydrogen makes about 10% of our body weight.
Magnetism is caused by the movement of charged particles (for example,
electrons). Most items become demagnetized when electrons spin in opposite
directions. They are magnetic elements because the electrons in other materials
rotate in the same direction as theirs. Because hydrogen only has one electron, it
retains magnetic characteristics. In other words, the hydrogen atoms are
surrounded by a very weak magnetic field. Magnets have two poles: positive and
negative. Because opposed charges attract each other, moving the positive pole
of the magnet near the hydrogen atom causes the opposite poles of the charge
to align so that they face each other.
Water (H20) makes up 60% of the human body. This molecule is made up of
hydrogen atoms. Electromagnetic energy, specifically radio waves, can energise
these hydrogen atoms. As the radio energy is absorbed, the atoms begin to
oscillate; this oscillation is known as precession, and the frequency at which the
atoms oscillate is known as the Larmor frequency. Even after the radio waves are
switched off, the atoms continue to oscillate and release the radio energy they
have been holding. This process is referred to as "nuclear magnetic resonance"
(NMR). This approach is employed during MRI.
An MRI scanner has four primary components-
A powerful magnetic field surrounds the patient.
The gradient coil divides the magnetic field into smaller, varying-intensity
sections, allowing us to isolate certain organs or tissues. controls the camera's
movement.
Radiofrequency coil: The receiver coil (rf) receives reemitted RF, whereas the
transmitter coil (rf) transmits radiofrequency (input).
The radiation emitted by the body is then processed by a computer to generate
an image that shows which regions of the body are emitting more or less RF
waves.
MRI production-
MRI generates precise and detailed images by measuring the amount and
position of hydrogen and water in diverse body tissues. Because our bodies are
60-70 percent water, we can make very accurate images and analyse various
signals (for example, cerebrospinal fluid (CSF) shows bright in MRIs due to its
high-water content).
In different tissues, such as blood, fat, and bone, hydrogen atoms vibrate at
different frequencies. We can observe tissues and abnormalities more clearly by
selectively focusing RF waves to lower the brightness of certain tissues (such as
fat).
Contrast is a substance that can be injected into the body or consumed as a
"barium meal". Because of the chemical composition of the contrast material, it
will appear very bright on the scan. For example, injecting the patient with 5-15
, ml of gadolinium before the scan enhances the blood vessels (blood vessels) in
the image by making the blood clearer. Image modified and explained-
The light and dark parts of the image represent the specific chemical
environment/properties of the biological tissue. Magnetic field strength, gradient
roll, and radio wave pulse timing all affect image clarity. Depending on the size
and location of the organ being studied, different detector coils can be used.
After the results of the MRI scan, surgery is often postponed or guided more
precisely, reducing the need for exploratory surgery and, consequently, the risk
of infection.
FLOWCHART OF MRI PRODUCTIO
On a platform that slides inside the MRI scanner, the patient is positioned.
The patient is surrounded by a magnetic field produced by a powerful
magnet. The tissues of the body's hydrogen atoms line up with the
magnetic field.
Radiofrequency coils 'push' hydrogen atoms out of alignment with the
radiation waves they absorb.
The hydrogen atoms gradually realign with the magnetic field as the input
radiofrequency is withdrawn, reemitting the radiofrequency that was
absorbed.
By mapping the bodily regions that release the most/least energy, a
radiofrequency receiver coil captures the re-emitted energy and generates
an image.
Uses and Benefits- It identifies brain enlargement and haemorrhage.
Aneurysms in the brain, strokes, brain tumours, spinal tumours, and
inflammation are all common issues. After an injury, evaluate the spinal cord's
integrity. It is also used to describe spinal disc and vertebral issues. The
structural features of the heart and aorta can be examined to diagnose
aneurysms and ruptures. It contains information about the glands and organs of
the abdomen. Clinicians can diagnose patients with the greatest quality evidence
possible because to the availability of high-resolution photos. Cross-sectional
images of the body can be produced by MRI. Advanced computer algorithms that
integrate two-dimensional photos to produce a three-dimensional image which
make this conceivable. These images are created using large magnets, radio
waves and computers. MRI can frequently detect damaged areas of the brain
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