| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: understand the use of X-rays in imaging internal body structures, including an understanding of the term contrast in X-ray imaging |
Learning Objective/s:
- Explain the processes of bremsstrahlung and characteristic radiation that generate X‑rays in a tube.
- Describe how X‑ray attenuation produces images of internal body structures and define image contrast.
- Identify the factors (density, atomic number, thickness, photon energy) that influence image contrast.
- Evaluate the purpose and use of contrast agents such as iodine and barium in X‑ray imaging.
- Apply the contrast formula C = |I₁‑I₂| / (I₁+I₂) × 100 % to compare two regions.
|
Materials Needed:
- Projector or interactive whiteboard
- PowerPoint slides with tube diagram and attenuation graphs
- Printed worksheet with contrast calculations
- Sample X‑ray images (bone vs. soft tissue)
- Demonstration video of an X‑ray tube operation
- Calculator or spreadsheet for formula practice
|
Introduction:
Begin with a striking X‑ray image of a hand and ask students what makes the bones appear bright. Recall prior knowledge of electromagnetic waves and the concept of attenuation. Explain that by the end of the lesson they will be able to describe how X‑rays are produced, define image contrast, and calculate it for simple cases.
|
Lesson Structure:
- Do‑now (5') – Quick quiz on the electromagnetic spectrum and previous wave concepts.
- Mini‑lecture (10') – Explain X‑ray tube components and production mechanisms (bremsstrahlung, characteristic radiation) with diagram.
- Guided activity (12') – Use the attenuation equation to predict image brightness for different tissues; students work in pairs on a worksheet.
- Contrast exploration (10') – Introduce the definition, influencing factors, and formula for contrast; calculate contrast for two sample regions.
- Contrast agents discussion (8') – Show examples of iodine and barium, discuss why they are used.
- Formative check (5') – Exit ticket: one sentence describing how photon energy affects contrast.
|
Conclusion:
Summarise the link between X‑ray production, attenuation, and image contrast, highlighting the role of contrast agents. Students complete an exit ticket calculating contrast for a given pair of intensities. Assign homework to research a clinical case where contrast agents improved diagnosis.
|