Author: Márcia Costa Edited by: Jun Hon Pang
Radiotherapy is a type of cancer treatment that uses ionising radiation to kill cancer cells. Generally, radiation, in the form of high-energy X-rays or electrons, is delivered using a device called a linear accelerator (LINAC). So far, treatment planning of radiotherapy has been achieved by using computed tomography (CT) imaging and magnetic resonance imaging (MRI). Treatment planning involves targeting the tumour, while sparing the adjacent healthy tissues as much as possible. This is extremely important because radiation can kill all types of cells; thus the more healthy tissue that is exposed, the greater the risk of the patient suffering from side effects.
Radiotherapy treatments are delivered in multiple sessions, so patients have to be repositioned in the LINAC and treatment plan adapted for each treatment session on different days. This is done using only CT imaging. However, CT imaging does not always allow sufficient differentiation between tumour and healthy soft tissue, since both types of tissue have a similar appearance in the image. In recent years, efforts have been made to use an imaging technique with better soft tissue contrast - MRI, for daily positioning and treatment planning adaptation during the multiple radiotherapy sessions.
More recently, a new technology has been developed by combining both MRI and the LINAC within a single multimillion pound machine: the MR-LINAC. It allows simultaneous capturing of MR images during radiotherapy, and it aims to be a higher standard of precision radiotherapy. The first MR-LINAC device in the UK was installed on the Sutton site of The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, London.
We interviewed Prof Uwe Oelfke, Head of the Joint Department of Physics at The Institute of Cancer Research (ICR) and The Royal Marsden, who spearheads the project, to find out more about the project.
1. What is MR-LINAC technology and why do we need it? What is the potential/benefit?
The MR-LINAC 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. Once fully developed, the MR-LINAC will allow constant monitoring of the patient during treatment and precise dose targeting of the tumour, avoiding damage to healthy tissue. This will allow doctors to increase the radiation dose delivered directly to a tumour, while reducing side-effects.
2. Why was The Royal Marsden and the ICR the best place to install an MR-LINAC? How important is this to the radiotherapy field?
The Royal Marsden and the ICR together is one of the largest comprehensive cancer centres in Europe. The Royal Marsden treats about 6,500 new cancer patients with state of the art radiotherapy each year and the linked ICR research teams provide prime expertise in MRI and radiation therapy physics. The combined medical expertise and research experience from both organisations provides the ideal location for developing the full clinical potential of this highly innovative technology. The installation of the MR-LINAC was made possible by a £10 million grant from the Medical Research Council to the ICR, with additional support from The Royal Marsden Cancer Charity. We were received funding from Cancer Research UK for the preparatory research.
3. Now the device has been installed, what is the work being performed at the moment?
Currently, we are pursuing two major activities. First, we are optimising the quality of the MR images by studies with healthy volunteers and cancer patients for a number of anatomical locations. Second, we are developing quality assurance procedures and commissioning protocols for the MR-LINAC technology to ensure a safe and reliable operation of the technology for the upcoming clinical treatments commencing later this year.
4. What are the planned clinical trials? Have they been chosen?
There are a large number of clinical trials being developed within the international MR-LINAC consortium organised by Elekta, as the manufacturer of the MR-LINAC technology. As primary clinical focus, nine prominent cancer types were selected. Clinical researchers at the ICR and The Royal Marsden are currently leading the development of clinical protocols for prostate, breast, and cervical cancer and play a prominent role for treating lung, head and neck, and pancreatic cancer with the MR-LINAC.
5. What is, in your opinion, the future of the technology?
In my view the MR-LINAC has the potential to revolutionise high precision radiotherapy treatments for a number of cancer types. As a first step, the spatial accuracy of targeting tumours with radiation dose will dramatically improve, especially in the abdomen, through the exploitation of the superb soft-tissue contrast of MR images. Furthermore, MR images can be obtained continuously during treatment, such that any organ or tumour motion can be detected and accounted for, even while the patient is treated. And finally, the high-field MR technology with our 1.5T scanner will allow further biological characterisation of the disease in space and time enabling even more personalised high precision radiotherapy treatments in the future.
The MR-LINAC project is just starting but the hopes are high that it will improve patient care. The facility was opened by the Mayor of London, Sadiq Khan, in November 2016. One year later, in November 2017, the first healthy volunteers were MR scanned, including the MP for Sutton and Cheam, Paul Scully. These first volunteers did not receive any radiation, but the imaging data acquired provides valuable information for the development of MR-LINAC protocols before starting treating cancer patients.
Follow the latest news about the MR-LINAC on the ICR website: https://www.icr.ac.uk/news-features/mr-linac
Professor Uwe Oelfke began his career in Theoretical Nuclear Physics, gaining his PhD at the University of Hanover in 1990 and then moving to TRIUMF, Canada's national laboratory for particle and nuclear physics. Here he worked as a Postdoc, initially with the Nuclear Theory group and then moved to the Batho Biomedical Facility as a Research Associate, looking at Proton & Pion Therapy. At this stage he transferred from Nuclear to Medical Physics.
In 1997 he returned to Germany to join DKFZ in Heidelberg as a Research Associate, where he became a group leader in 2001 and received a Professorship of Medical Radiation Physics from Heidelberg University in 2004. During 15 years in Heidelberg, his research was focused on Adaptive and image-guided radiation therapy, treatment planning and modelling and Hadron therapy.
He firmly believes that Medical physics research on cancer imaging and therapy is an essential component to improve the clinical outcomes of radiation oncology. The ICR and The Royal Marsden, as a world leading comprehensive cancer centre, now initiates the next generation of radiotherapy treatments by combining the most recent developments in cancer biology, cancer therapeutics and medical physics in a truly interdisciplinary approach.
For this reason he moved to the UK and joined us in April 2013, as Head of the Joint Department of Physics, and is combining functional diagnostic imaging with new forms of image-guided radiation therapy to predict how tissues will react to radiotherapy treatment.