This higher tier covers Higher Tier Only: Why Gamma Beams Are Rotated in Radiotherapy within Uses & Hazards of Radiation for GCSE Physics. Revise Uses & Hazards of Radiation in Atomic Structure for GCSE Physics with 17 exam-style questions and 5 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 13 of 16 in this topic. This section is most useful once the core foundation idea is secure, because it adds the detail that pushes answers higher.
🎓 Higher Tier Only: Why Gamma Beams Are Rotated in Radiotherapy
In external beam radiotherapy, the gamma source is mounted on a machine (linear accelerator or cobalt-60 unit) that rotates around the patient. Multiple beams from different angles all converge on the tumour.
The result: the tumour receives a very high total dose (sum of all beams), while each entry path through healthy tissue receives only a fraction of that dose. This maximises the damage to cancer cells while minimising side effects to surrounding healthy tissue.
This is why patients sometimes need many sessions — the dose is spread out over time to allow healthy tissue to repair between treatments, while cancer cells (which divide rapidly) accumulate more damage.
Practice questions for Uses & Hazards of Radiation
Which type of radiation is used in smoke detectors?
Explain how a smoke detector uses an alpha source to detect smoke.