OCR A-Level Physics A H556
Practical Skills in the Written Papers
The Practical Endorsement
Physical Quantities and Units
Making Measurements and Analysing Data
Nature of Quantities
Motion
Forces in Action
Work, Energy and Power
Materials
Newton’s Laws of Motion and Momentum
Charge and Current
Energy, Power and Resistance
Electrical Circuits
Waves
Quantum Physics
Thermal Physics
Oscillations
Gravitational Fields
Astrophysics and Cosmology
Capacitors
Electric Fields
Electromagnetism
Nuclear and Particle Physics
Medical Imaging
PET scanning
- 3 things to know
- Papers 1, 2 and 3
Overview
Recall questions on positron-electron annihilation, fluorine-18 tracers, 511 keV gamma photons, coincidence detection and lines of response, forming PET images, uses in cancer and neurology, and cyclotron supply.
What you need to know
Answer each one before you reveal it.
Why might a hospital with a PET scanner require an on-site cyclotron or rapid delivery service?
What type of decay does fluorine-18 undergo, and what is its approximate half-life?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What are the products of positron-electron annihilation, and what are their properties?
Model answer
Two gamma photons of equal energy (511 keV each) that travel in opposite directions (180° apart).
- 2
What type of decay does fluorine-18 undergo, and what is its approximate half-life?
Model answer
Fluorine-18 decays by positron emission with a half-life of approximately 110 minutes.
- 3
In which imaging technique is fluorine-18 used as a tracer?
Model answer
PET (positron emission tomography) scanning.
- 4
Into which compound is fluorine-18 incorporated for PET scanning, and why does this compound accumulate in certain tissues?
Model answer
Fluorine-18 is incorporated into fluorodeoxyglucose (FDG), which accumulates in tissues with high metabolic activity.
- 5
What happens to a positron emitted from a tracer in PET scanning before detection occurs?
Model answer
The positron travels a short distance before encountering an electron, resulting in annihilation.
- 6
State the equation used to calculate the energy of each annihilation gamma photon from the rest mass of an electron or positron.
Model answer
E = mₑc², where E is energy, mₑ is the rest mass of an electron (or positron), and c is the speed of light.
Other ways to work this
The same content, four other ways.
What is inside Levo
Six ways to work the same material.
Every question in Medical Imaging, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
Or £46 a year, about £3.83 a month. Cancel anytime.