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Physics: unlocking the mysteries of tumours

With the discovery at the Large Hadron Collider at CERN of the Higgs boson – thought to be responsible for giving mass to everything in our universe – physics is helping us to decipher the very matter of our world. More tangible benefits from physics can be found in everyday technology – smartphones, optical fibres and solar panels. Now through the application of physics, scientists are developing life-saving methods of using ionising radiation for diagnosing and treating cancer.

"CMS Higgs-event" by Lucas Taylor. Licensed under CC BY-SA 3.0 via Wikimedia Commons.

Our Joint Department of Physics here at The Institute of Cancer Research, London, also spanning The Royal Marsden NHS Foundation Trust, is developing and applying techniques for cancer diagnosis, imaging and treatment – in particular radiotherapy.

Radiotherapy generally uses high-energy X-rays of a few million electron volts targeted to the tumour to break double-strand DNA, and damage tumours irreparably. Because X-rays have to pass through normal organs and structures in the body en route to their target, some collateral damage may occur to these tissues. So the goal of radiotherapy is to cure the tumour whilst minimising the dose to these other tissues – a goal that has not changed since the first radiation treatment was performed in 1896. But the way in which we achieve this goal has changed dramatically in recent years.

Professor Uwe Oelfke, who is the Head of the Joint Department of Physics, says: “Our work is focused on solving physics-related problems with delivery of radiation to tumours through advanced radiotherapy techniques, such as intensity modulated radiation therapy (IMRT) and image-guided radiation therapy (IGRT) – which allow radiotherapy to be shaped precisely to the complex shape of tumours. But one of the major hurdles in delivering radiotherapy is down to the tumour moving, which is particularly problematic when dealing with respiratory movement in lung cancer.”

We are continually seeking out the best way to track tumour movement, and central to realising that vision is developing one of the world’s most advanced radiotherapy machines – the MR Linac. Along with our partner The Royal Marsden, we are the first institution in the UK – among a select group of international medical centres – to own and develop the world-leading MR Linac technology.

“This state-of-the-art machine merges the separate technologies of magnetic resonance imaging (MRI) and a linear accelerator to target radiotherapy very precisely,” explains Professor Oelfke. “The MR Linac will be able to image tumours in real-time during radiotherapy, so we can accurately locate tumours and deliver higher doses of radiation to cancers, avoiding damage to the neighbouring organs. This technology has huge potential to directly benefit not only Royal Marsden patients but patients right across the NHS and beyond.”

One other project within the group is to improve treatment planning techniques by developing software which allows the clinician to directly see and adjust the radiotherapy dose on a graphical representation of the patient’s anatomy.

“As the whole treatment planning process is in real time, it simplifies and increases the effectiveness of complex treatment planning across many clinical indications,” adds Professor Oelfke.

Newer radiotherapy techniques using proton beams – charged particles – are revealing further challenges as Professor Oelfke explains: “The treatment preparation and execution errors can be well controlled with IGRT procedures for photon beams – the most common type of radiotherapy. But when using ‘hadron therapy’ – consisting of charged particles such as protons, helium and heavier ions such as carbon – we are encountering difficulties in treatment planning and delivery due to the physical behaviour of the ions.

"While photon doses decrease slowly and mainly exponentially as they penetrate tissue, protons deposit almost all of their energy in a sharp peak – the Bragg peak – at the very end of their path. Taking these properties into account, we are designing robust and biologically optimised treatment plans for proton therapy."

Professor Oelfke has ambitious plans for the department and says: “One of my future interests is to combine the ICR’s unique drug development programme with radiotherapy to find the best treatments for cancer patients. And by collaborating with other universities in London on physics-related projects, we will be able to share resources and ideas, so we can reach our research goals more quickly.”

Physics continues to help us unlock the mysteries of our cosmos and the world we live in, and is one of our most powerful enablers of innovation and discovery. When applied to cancer medicine, physics is enhancing the diagnosis and treatment of the disease, and improving the quality of life of patients around the world.
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