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MR Linac: first healthy volunteer scanned in pioneering new radiotherapy machine

MR Linac scanner with Ross Lydall inside

The first healthy volunteer has been scanned using a revolutionary new type of radiotherapy machine, which is set to transform cancer treatment by allowing radiation to be aimed at tumours with extreme precision.

The scan is part of the initial trials of the MR Linac. The machine’s technology allows for magnetic resonance images to be generated at the same time as X-ray radiation beams are delivered to the tumour.

The technology is set to set to make radiotherapy more effective and reduce its side-effects, by targeting radiation precisely at the patient’s tumour. It can even take into account movements of the tumour in the body, for instance as a patient breathes.

The Institute of Cancer Research, London, and The Royal Marsden NHS Foundation Trust are the first in the UK to install an MR Linac machine.

The healthy volunteer did not receive any radiation treatment but was scanned to provide MRI images to help test and calibrate the equipment. Clinical studies that begin next year will trial both the radiotherapy and MRI scanning elements of the MR Linac.

First healthy volunteer

The volunteer – Ross Lydall, Health Editor of the London Evening Standard – was scanned as part of the PRIMER study, which involves producing MRI scans of healthy volunteers, followed by patient volunteers. These cancer patients will be scanned before and during their radiotherapy treatment.

The researchers will use the information from the scans to help decide the best ways to use the imaging capabilities of the MR Linac. This will ensure it is used most effectively in trials where the radiotherapy is combined with the precise MR imaging functionality.

By combining an MRI scanner with the technology to deliver radiotherapy, the MR Linac works slightly differently from the conventional imaging kit. This means the researchers need to find the best ways to run the machine so it produces the highest-quality images.

Experiencing the scan

Ross described his experience of being scanned in the MR Linac:

“Going into the tunnel of the scanner, I felt bit like an astronaut – I imagined I was Tim Peake in the International Space Station. It did feel a little alarming at first but once I closed my eyes and relaxed, the time flew by.

“It was an honour to be the first volunteer to be scanned and it was fascinating to learn how my images will help the research to develop the technology. I feel very happy to do even a tiny bit to help people with cancer who might need this machine in the future.”

The MR Linac machine combines two technologies — an MRI scanner and a linear accelerator — to precisely locate tumours, tailor the shape of X-ray beams in real time, and accurately deliver doses of radiation even to moving tumours.

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Moving towards treating cancer patients

The MR Linac is based at the Sutton site of the ICR and The Royal Marsden, and the technology will continue to be developed ahead of the first clinical studies to treat cancer patients in summer 2018.

Professor Uwe Oelfke, Head of the Joint Department of Physics at the ICR and The Royal Marsden, who leads the physics research into the MR Linac, said:

“The MR Linac is an incredibly sensitive and sophisticated device – we’re at the cutting edge of a technology that combines physics, computing and medicine.

“The level of detailed work to calibrate and perfect it is equivalent, to the effort that goes into preparing a Formula One car before a Grand Prix. It’s exciting to have the opportunity to test drive the machine as we work towards trialling its full capabilities.”

MR Linac scan images, early and late

Image: These scans show the bladder changing over the course of the scan (30-40 minutes).

Hitting a moving target

The MR Linac is expected to be especially effective for cancers which move during radiotherapy or change position or shape between scanning and treatment — for instance through breathing, bladder filling or bowel changes. Examples are lung, cervical, prostate, bowel and bladder cancer.

Professor Robert Huddart, Professor of Urological Cancer at the ICR and Consultant in Urological Oncology at The Royal Marsden, who is leading the PRIMER trial, said:

“Although a person may lie perfectly still, the inside of their body, including the tumour, may move and even change shape. Changes of a few millimetres might not seem a lot but it is significant when it could be the difference between hitting healthy tissue instead of the tumour.

“Aiming at a moving target presents a real challenge in radiotherapy because we only want to hit the tumour and avoid the healthy tissue. The MR Linac has been designed to overcome this challenge and really could be a game-changer in radiotherapy.

“By seeing the tumour as we aim the radiation at it, we can be more confident of a direct hit. We should ultimately be able to attack the tumour with a higher dose of radiation each time, meaning we can treat some patients that are currently difficult to treat effectively, and many patients may need fewer doses in total.

“If our trials are successful, we will be able to deliver a much more effective treatment for cancer patients that will hopefully have fewer side effects.”

Making the machine possible

The installation of the MR Linac was made possible by a £10m grant from the Medical Research Council to the ICR, with additional support from The Royal Marsden Cancer Charity.

As well as the MRC funding for the MR Linac project, scientists were also funded by Cancer Research UK for much of the preparatory research and now receive support from the NIHR Biomedical Research Centre at The Royal Marsden and the ICR.

Physicists at the ICR and The Royal Marsden have been actively developing the technology for several years as part of an international consortium initiated and coordinated by the company Elekta, which makes the MR Linac (also known as the Elekta Unity Systems), and MR partner Phillips.

The UK team previously showed that it is possible to target radiation precisely at lung tumours with the MR Linac using real-time imaging. The research demonstrated that the system can be calibrated to deliver X-rays accurately in the presence of the magnetic field used to generate MRI images — overcoming a key scientific challenge.


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