| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: understand that the gamma-ray photons from an annihilation event travel outside the body and can be detected, and an image of the tracer concentration in the tissue can be created by processing the arrival times of the gamma-ray photons |
Learning Objective/s:
- Describe the positron‑electron annihilation process that produces two 511 keV gamma photons.
- Explain how coincidence detection and time‑of‑flight (TOF) measurements locate the annihilation event.
- Apply the TOF equation \(x = \frac{c\,\Delta t}{2}\) to calculate the position along a line of response.
- Interpret a reconstructed PET image to identify regions of high tracer uptake.
- Evaluate the main detector technologies and safety considerations used in PET.
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Materials Needed:
- Projector or interactive whiteboard
- PowerPoint slides with diagrams of PET annihilation and detection
- Handout summarising TOF reconstruction steps
- Sample PET image for analysis
- Clicker/online quiz tool for formative checks
- Optional: simulation software showing coincidence detection
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Introduction:
Begin with a striking PET image of a tumour to capture interest, then ask students what they know about X‑ray production and photon detection. Review the concept of electron‑positron annihilation and the 511 keV photons it creates. State that by the end of the lesson they will be able to trace these photons from the body to a reconstructed image.
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Lesson Structure:
- Do‑now (5 '): Quick quiz on X‑ray production and photon energy to activate prior knowledge.
- Mini‑lecture (10 '): Explain positron emission, annihilation, and the 511 keV gamma photons.
- Animation demo (8 '): Show coincidence detection and the formation of a line of response (LOR).
- Guided calculation (12 '): Students work through sample Δt values using \(x = \frac{c\,\Delta t}{2}\) and record positions.
- Group image analysis (10 '): Examine a PET slice, locate high‑uptake regions, and relate them to the calculated positions.
- Formative check (5 '): Clicker questions targeting each learning objective.
- Recap & exit ticket (5 '): Students write one key concept they mastered and any remaining question.
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Conclusion:
Summarise how annihilation photons escape the body, are captured by detector rings, and are processed via TOF to produce quantitative images. Collect exit tickets to gauge understanding and assign a short homework task: read a case study on PET oncology and prepare a one‑paragraph summary of how image reconstruction informs treatment decisions.
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