Honorata Chajecka-Szczygielska, Senior Radiotherapy Physicist

I’ve been working in the Joint Department of Physics at The Royal Marsden in Sutton for 10 years and am one of a team of physicists responsible for the quality control of our linear accelerators – machines we use to treat patients with radiotherapy. We have seven linear accelerators, or linacs, in Sutton and four in Chelsea. I work closely with engineers, radiographers and clinical oncologists to ensure the machines are safe and effective for patients.

If a machine breaks down or develops a fault, an engineer will fix the problem and I’ll verify that it is delivering the precise dose of radiation before any patients are treated. This is key to ensuring that treatment is safe and effective.

Working order

Each linac has a detailed quality control check every month. When I sign my name in the log book to say that a machine is fit for clinical use, it’s a big responsibility, so our checks are extremely stringent. I’ll ensure that the dose levels are correct and the mechanics of the whole machine – from the devices that shape the beams of radiation to the bed patients lie on – are working. I’ll also check the imaging function of the linac, that the laser beams used to position the patient are aimed precisely at the specified point, and that the emergency stop buttons are working. Going forward, I’m trying to make quality control faster and digitise some of the processes.

We’ll also test the individual treatment plans, which are produced by a physicist using computer software. They set out how many sessions – known as fractions – of radiotherapy a patient should have, the amount of radiation they should receive, and the angles and shapes of the beam. These plans are then signed off by the consultant.We use dosimetry ‘phantoms’ to test the treatment plans and verify the radiation dose. These are essentially sophisticated mannequins and can contain more than a thousand separate radiation detectors.

These are essentially sophisticated mannequins and can contain more than a thousand separate radiation detectors

Test and plan

When I’m not working with one of the linacs, I’ll be in the dosimetry lab. Here, I’ll analyse measurements, test our equipment and plan my next quality control system. I usually work standard office hours, but if we need to spend time on one of the machines when the Radiotherapy Department is busy, we’ll do our checks and testing in the evening.

At the moment, we have a new linac we’re commissioning for use. These machines are incredibly complex – you can’t just plug it in and put a patient on it. We need to acquire all the radiation beam data required for treatment, enter it into a computerised treatment planning system, plan and verify numerous procedures and train all personnel.

Although we don’t work directly with patients, I find commissioning a new linac so interesting. In fact, making sure that the machines are working to their highest specification is my favourite part of the role.