| Date | November 2016 | Marks available | 3 | Reference code | 16N.3.HL.TZ0.20 |
| Level | Higher level | Paper | Paper 3 | Time zone | Time zone 0 |
| Command term | Explain | Question number | 20 | Adapted from | N/A |
Question
State the property of protons used in nuclear magnetic resonance (NMR) imaging.
[1]
a.
Explain how a gradient field and resonance are produced in NMR to allow for the formation of images at a specific plane.
[3]
b.
Markscheme
«proton» spin
a.
strong B field applied to align proton spins
OWTTE
cross-field applied to give gradient field
OR
each point in a plane has a unique B
RF field excites spins
protons emit RF at resonant/Larmor frequency dependent on Total B field
RF detected shows position in the plane / is used to form 2D images
Allow features to be mentioned in any order
b.
Examiners report
[N/A]
a.
[N/A]
b.
Syllabus sections
Option C: Imaging » Option C: Imaging (Additional higher level option topics) » C.4 – Medical imaging (HL only)
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