What does a radiotherapy physicist do?
Radiotherapy physicists help make cancer treatment accurate and safe. They calculate and check radiation doses so treatment reaches the intended area while limiting exposure to healthy tissue.
Planning and checking treatment
Physicists use patient images and specialist software to help plan treatment. They calculate radiation dose and check that a plan can be delivered accurately.
They work closely with oncologists, radiographers, technologists, engineers and other scientists.
Testing the equipment
Before a new treatment machine is used, it needs detailed testing, known as commissioning. Regular quality-assurance checks then help the team confirm that it is working as expected.
Dosimetry means measuring or calculating radiation dose. It is an important part of checking both equipment and treatment plans.
What might a working day include?
- Calculating doses and reviewing treatment plans
- Testing machines and checking measurements
- Investigating an unexpected result
- Working with colleagues on a complex treatment
- Writing software or analysing data
- Researching and introducing new techniques
Would the work suit you?
You may enjoy it if you like careful technical work, solving practical problems and seeing how science helps patients. You will need to explain your reasoning, keep clear records and ask for help when a result needs further checking.
Physicist or therapeutic radiographer?
These professions work closely together but have different training, registration and responsibilities. If you are considering both, compare their day-to-day work and training requirements.
How to train
Radiotherapy Physics is one of the Medical Physics specialties in England’s Scientist Training Programme (STP). Wales, Scotland and Northern Ireland have their own recruitment arrangements.
Compare treatment and imaging work
Explore how radiotherapy differs from the imaging specialisms.
Sources
Guidance checked: 18 August 2026