New Radiotherapy TrueBeam Linear Accelerator 'Oak' installed at Cheltenham General Hospital

Linacs work by accelerating electrons to generate high-energy X-rays or electron beams, which can be precisely directed at a patient’s tumour. These treatments are designed to destroy cancer cells while sparing surrounding healthy tissue, enhancing both effectiveness and safety.

Linacs are major investments, costing at least £2 million each. The advanced radiotherapy treatment machine, supplied by Varian, has now been successfully installed with 'Oak' marking the Varian engineer's 250th installation.

The Trust's specialist Medical Physics team is currently commissioning the unit – a crucial phase ensuring the system is calibrated for safe and effective treatment. The commissioning process takes around three months before the unit is fully handed over to the Radiotherapy Radiographers. The ambition is for the first patients to be treated on the new Linac from Spring 2025.

It is essential that all the Trust's Linacs match, as this allows patients to receive treatment on any of the hospital’s machines without needing a completely new treatment plan. If a patient transfers from another cancer centre, however, a new plan would be created as each centre’s machines may have slightly different settings.

Continuing a tradition at Cheltenham General Hospital, radiotherapy treatment units are named after the tree pictured in their sky ceiling – calming ceiling panels designed to create a more soothing environment for patients undergoing treatment. This latest unit has been named 'Oak', symbolising strength and resilience.

Lisa Addis, Radiotherapy Operational Manager, said:
"It’s taken many months of project work, so thanks to all involved, including our partners GMS Facilities for their support throughout the project."

The installation of 'Oak' marks a significant step forward for the Oncology Centre. Once fully operational, all four high-energy treatment units will be the same, streamlining processes and enhancing safety in cancer treatment delivery.

Cheltenham General Hospital now operates four Linacs, all commissioned to match output, running from 8am to 6pm, 5 days a week. Alongside the commissioning process, the Medical Physics team also calibrates each machine every month to maintain precision and safety.

This latest investment in cutting-edge radiotherapy technology is another step towards further improving cancer treatment for patients in Gloucestershire and beyond.

Behind the Scenes: How Medical Physics Commissions a Linac

Before the new Linac 'Oak' can begin treating patients, it must undergo a detailed commissioning process led by Principal Physicist Jason Brimelow and the Medical Physics team. This involves extensive testing to ensure that the radiotherapy beam delivers the precise dose required for safe and effective cancer treatment.

A key part of the commissioning process involves testing the beam using a large tank of ionised water (pictured). Jason explains:

"The human body is about 70% water, so the water tank allows us to measure and test the radiotherapy beam dose to ensure it matches the predicted dose specified by the treatment planning computer system.

"The machine comes with factory settings, but we need to commission it to ensure it exactly matches our other Linacs. For every millimetre of this large tank of water, we test and measure the dose in both directions, then we repeat the process at several different depths – which explains why commissioning takes so long."

If the results from the water tank testing do not perfectly match the predicted beam profile from the treatment planning system, adjustments can be made. Jason continues:

"If our treatment planning system thinks the beam should look a certain way, and the testing in the water reveals a different answer, we can adjust the algorithms in our planning computer to ensure they match perfectly."

Greater accuracy means fewer appointments

Advances in radiotherapy technology now mean that treatments are more precise and efficient than ever before. For example, breast cancer patients may now require as few as five treatment appointments, compared to significantly more in previous years.

Each patient’s treatment area is mapped using a CT scan and the latest camera systems in the Linac track the tumour in real time as the patient breathes, coughs or moves. The machine automatically pauses treatment if the tumour moves out of range and resumes once it is back in position, minimising the impact on healthy tissue. The system also adjusts the patient’s bed position by as little as half a millimetre to ensure pinpoint accuracy.

Our Principal Physicist

Jason Brimelow has worked for the trust for 28 years, personally commissioning every Linac used, including the one at our satellite radiotherapy unit at Hereford County Hospital. He holds a Master’s degree in Medical Physics and reflects on his career:

"I fell into working in radiotherapy and I’ve seen a lot of changes over the years. It’s been a privilege to witness the tangible benefits of leading-edge technology and how science really helps people survive and recover. Each time we invest in a new Linac, we can see that further progress has been has been made, which is incredibly rewarding. The Trust is also a great place to work!"