| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: understand that computed tomography (CT) scanning produces a 3D image of an internal structure by first combining multiple X-ray images taken in the same section from different angles to obtain a 2D image of the section, then repeating this process a |
Learning Objective/s:
- Describe how X‑ray tubes generate bremsstrahlung and characteristic radiation.
- Explain the exponential attenuation of X‑rays in matter.
- Summarise the two‑stage CT process: acquisition of 2‑D projections and reconstruction of slices.
- Interpret how stacked 2‑D slices form a 3‑D image.
- Evaluate safety principles (ALARA, shielding) in CT imaging.
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Materials Needed:
- Projector with slide deck on X‑ray production and CT.
- Whiteboard and markers.
- Handouts containing key equations and CT flowchart.
- Computer simulation of CT reconstruction (online filtered back‑projection demo).
- Sample CT images for analysis.
- Lead apron (demonstration of shielding).
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Introduction:
Begin with a striking CT scan image of a human head, asking students what allows us to see inside without surgery. Recall prior learning on X‑ray generation and attenuation, linking it to the need for multiple angles. State that by the end of the lesson they will be able to explain how those X‑ray projections are combined to produce a 3‑D model.
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Lesson Structure:
- Do‑now (5') – quick quiz on X‑ray production (multiple choice) to check prior knowledge.
- Mini‑lecture (10') – review bremsstrahlung, characteristic radiation, and the attenuation law.
- Interactive demonstration (10') – use a computer simulation to rotate the X‑ray source around a virtual slice and collect projections.
- Guided reconstruction activity (15') – students work in pairs with a worksheet to apply the filtered back‑projection concept; teacher circulates for support.
- Whole‑class discussion (5') – compare the reconstructed slice to the original, discuss stacking slices into a 3‑D image, and review safety considerations.
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Conclusion:
Summarise how CT converts many 2‑D X‑ray images into a volumetric representation and why this offers diagnostic advantages. Ask students to write one key takeaway on an exit ticket. Assign homework: read the provided handout on CT algorithms and solve the practice question on total scanned length.
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