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Transcript of MRI
Magnetic Resonance Imaging
By: Raina Shah
What Is An MRI?
How Does It Work?
a test that uses magnetic field and pulses of radio wave energy to make pictures of organs and structures inside the human body.
doctors perform MRI scans to diagnose multiple sclerosis, brain tumors, torn ligaments, tendonitis, cancer, strokes, and etc.
an MRI is a best way to see the inside of a human body without cutting it open.
for an MRI test, the area of body being studied is placed inside a special machine that contains a strong magnet.
pictures of the scan are digital images that can be stored on a computer to analyze later on.
patients are asked to remove jewelery, credit cards, and other things, so the scan can be performed in an accurate manner.
you are put into a machine (a big hole) and subjected to loud noises, and have to lie perfectly still.
uses a very strong magnet which consist of coils of wire through which a current of electricity is passed, creating a magnetic field.
reduces the resistance in wires to zero to produce the large magnetic field which requires a lot of energy.
superconductive magnets are very expensive, but the strong magnetic field they produce creates the highest-quality imaging.
other magnets such as resistive and permanent can be used.
there are three gradient magnets which have a lower strength than the main magnet.
main magnet creates intense stable magnetic field around patient.
gradient magnets create lower magnetic field consumed by other parts in the body
coils transmit radio frequency waves into the patient’s body.
there is a gravitational field because it does exert a force on the MRI machine.
once patient is in the centre of magnetic field, scan begins.
hydrogen atoms are used to detect from patient's body to develop scans.
these atoms spin on their axis, and have a strong magnetic movement.
once introduced to magnetic field, atoms line in the direction of field.
hydrogen protons line up so they are pointing at patient's head or feet.
most cancel out but a few out of millions don't because they don't have a pair.
these leftover protons are used to create the image.
releases a radio frequency pulse specific to hydrogen.
directs this pulse to the body being examined.
when pulse is applied, unmatched protons absorb energy and resume spining in different directions.
this part is called "Resonance"
radio frequency pulse forces atoms to spin at a certain frequency, and in a specfic direction--> called Larmour Frequency
three gradient magnets then come into play.
are arranged in the main magnet, so they can change the magnetic field of the main magnet.
allows you to take an image of any part of the body.
these magnets can manipulate everything, so machine doesn't need to be moved.
End of Scan
radio frequency pulse is turned off.
hydrogen protons return to their natural state, and release energy that they absorbed from pulses.
When they do this, they give off a signal that the coils pick up, and sent it to the computer system.
does not use ionising radiation
beneficial to children, and when examining the abdominal parts of the body where radiation used is high.
helps diagnose severe medical conditions.
strong magnetic fields produced may cause severe long term health effects.
can raise the risk of cancer, and other diseases because magnetic field is increased to achieve accurate images.
thermal burns, hearing loss, and projectiles.
Several equations were introduced in Chapter 7 and 8 which related to the electrical fields and magnetic fields.
due to high amounts of electricity generated, contributes to the amount of greenhouse gases released.
causes an increase in carbon footprint.
carbon footprint measures your impact in generating the greenhouse gases.
contributes in a negative manner to climate change, thus creating global warming.
global warming causes an increase in temperature, even in cold climates where specific animals are not suitable to this type of climate.
Burning Fossil Fuels
About three-quarters of greenhouse gas emissions that are attributed to humans come from burning fossil fuels.
we burn fossil fuels when we operate cars, use electricity, heat our homes etc.
As result, an MRI, due to large amounts of electricity used in order for it to work, burns high amounts of fossil fuels.
price to buy an MRI machine can range from $150,000 to $2 million.
it depends on the type of magnet the machine has and magnetic field strength.
for a company buying this machine would have to pay a lot.
Access to MRI scans provide quicker detection of health issues, saving unnecessary attempts at treatment.
Magnetic Force On Moving Charges
Magnetic Force on a Current-Carrying Conductor
What Effect Does A Uniform Magnetic Field Have on the Motion of a Moving Charge?
uses superconducting magnets to create a magnetic field around the body.
this field is typically more than 100 000 times as strong as Earth's magnetic field.
magnetic field applied by the MRI alters the magnetization of the body's atoms as the MRI unit scan soft tissues in the brain, heart, eyes, and other organs.