Question 18N.3.HL.TZ0.15
| Date | November 2018 | Marks available | [Maximum mark: 5] | Reference code | 18N.3.HL.TZ0.15 |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | Describe, Outline | Question number | 15 | Adapted from | N/A |
In nuclear magnetic resonance imaging (NMR) a patient is exposed to a strong external magnetic field so that the spin of the protons in the body align parallel or antiparallel to the magnetic field. A pulse of a radio frequency (RF) electromagnetic wave is then directed at the patient.
Describe the effect of the RF signal on the protons in the body.
[1]
protons spin direction changes
OR
proton energy state changes ✔
Outline the measurement that needs to be made after the RF signal is turned off.
[2]
Relaxation time «of signal/proton spin» ✔
Location/time delay of the emitted RF signal ✔
Describe how the measurement in (b) provides diagnostic information for the doctor.
[2]
Relaxation time gives information on tissue type/density/health/OWTTE✔
Location information provides 3D image/OWTTE✔