Radiotherapy Physics
Medical Physicists in Radiotherapy
Radiotherapy is a form of cancer treatment that delivers X-rays to cancer cells with the aim of killing them. Treatment is most commonly delivered using a linear accelerator – a large, rotating machine that sends out invisible X-rays.
A radiotherapy department relies on the expertise of many professional groups, including radiographers, doctors, nurses, engineers and medical physicists. Medical physicists are scientists with a strong understanding of X-rays, human anatomy and computer systems.
This page gives an overview of the main roles of medical physicists in providing cancer care.
Treatment planning – creating treatments tailored to each patient
Medical physicists help create and check each patient’s treatment plan. This includes programming how the linear accelerator rotates to deliver the correct dose of X-rays to the tumour while limiting radiation to healthy tissue.
Every treatment plan is unique, reflecting each patient’s individual anatomy and tumour. Once a plan is completed, it is independently checked by another physicist to reduce the risk of errors.
Quality assurance – ensuring accurate treatment delivery
Medical physicists carry out routine testing of linear accelerators to ensure they perform exactly as expected. This process is known as quality assurance.
Quality assurance helps ensure treatments are delivered accurately and consistently, providing patients with safe and reliable care throughout their treatment course.
Brachytherapy – a specialised form of radiotherapy
Brachytherapy is a type of radiotherapy used to treat certain cancers, particularly some cervical cancers. Radiation is delivered from inside the body by placing a small radioactive source near or inside the tumour.
Physicists carefully calculate the position and duration of the source to maximise tumour treatment and minimise exposure to healthy organs. The source itself is no larger than a grain of rice.
Medical physicists also test the equipment used to store and move the radioactive source. Each new source is measured to confirm its strength before it is used in patient treatments.