Medical Imaging - The Physics of Light Microscopes and Magnetic Resonance (MRI) units

Essay by LordOrangeHigh School, 12th gradeA+, November 2007

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Medical Physics

Extended Response Task

The Physics of Medical Imaging

Ben Cotterill - 23/4/07

Part 2 - Studying a medical imaging technique

Magnetic Resonance Imaging


Introduction The main components used in Magnetic Resonance Imaging (MRI) are a strong magnetic field and a certain radio frequency. The radio frequency tells the computer 'what it sees', allowing the computer to devise an image. The magnetic field is required to allow the radio frequency to do its job.

MRI relies on tissue density and the unique 'magnetic' properties of a hydrogen atom.

The "Magnetic" in MRI

The coils of the magnets are submerged in liquid helium (4.4K, about -269.11 oC) to reduce resistance in the wires. These magnets produce the required 0.5 - 2.0 Tesla.

The "Resonance" in MRI

The second important element in an MRI scan requires a radio frequency (RF) signal.

Inside the human body, there are billions of hydrogen atoms. These hydrogen atoms spin on their axis randomly when not in contact with strong magnetic fields (See below left)