MRI scanner

Question 1

How is an image produced on an MRI scan?

Answer 1

• nuclei in the body possess a spin which creates a magnetic field
• When in the MRI machine, the nuclei align to the main magnetic field
• nuclei process at the same speed if the magnetic field strength is the same
• lamour frequency Is the rate the nuclei spin
• Radio-frequency added will cause certain nuclei possessing the correct labour frequency will be knocked out of alignment to 90 degrees
• RF is stopped and the nuclei are said to ‘relax’
• When the nuclei relax, they lose energy and emit it in the form of EM radiation
• detector detects EM photons
• use of small gradient coils creates certain frequencies fr certain tissue types

Question 2

What does MR safe mean?

Answer 2

No risk to the patient but may affect the quality of the image

Question 3

What does MR compatible mean?

Answer 3

Safe and won’t effect image quality

Question 4

uses of MR in RT?

Answer 4

• clearer images than CT
• used to aid diagnosis eg, brain tumours
• can show how deeply tumours have extended to body tissues