*Device marketed for research applications only. Not for clinical use. Elekta’s MR-linac is a work in progress and not available for sale or distribution.
Currently, radiotherapists can only use high-quality MR images obtained before treatment for guidance during radiotherapy. This is less than ideal, since MRI is known for its excellent contrast when imaging soft tissue, which is the type of tissue that most shifts around depending on the position of the patient.
Real-time, high-quality visuals of the internal anatomy of the patient during beam delivery would revolutionize radiotherapy, enabling adaptation of the beam at the time of treatment. Philips is part of a research consortium that is developing the high-field MR-guided linear accelerator technology (MR-linac, see also the previous article in Hot Spot). The consortium is currently evaluating the MR-linac in a non-clinical setting. The aim of the MR-linac is for physicians to be able to adapt the treatment to patient movements or breathing.
Combining technologies to fulfill a unique vision
Elekta’s MR-linac combines two technologies – an MRI scanner and a linear accelerator – in a single system. It would allow physicians to change the direction of the beam during beam delivery and tailor the shape of X-ray beams in real time, responding to information from continuous MR imaging.
Graphic rendering of the MR-linac system. Yellow: illustration of the magnetic field of the MRI scanner. Blue: the treatment beam emitted by the linear accelerator.
Installation of the MR-linac at the MD Anderson Cancer Center.
MR-adaptive radiation therapy with the MR-linac could open up a truly unique way to treat cancer, establishing a new vision for clinical radiation oncology. The combination of an advanced digital linac and an MRI system could greatly enhance real-time visualization of cancer targets and avoidance structures during the delivery of therapeutic radiation.
Worldwide collaboration in MR-linac research consortium
The MR-linac is being developed by a consortium, led by Elekta. Philips is a member of the Elekta MR-linac Research Consortium as the strategic MRI technology partner. The consortium also includes several internationally renowned cancer centers.
The MR-linac combines a digital X-ray linac, a purpose-built high-field 1.5T MRI scanner and an online adaptive workflow to create an integrated machine. The MR-linac is being developed with the best state-of-the-art operating characteristics of both magnetic resonance imaging (MRI) and radiotherapy modalities along with integrated software.
Growing number of MR-linac installations
The University Medical Center (UMC) in Utrecht, the Netherlands, was a founding member of the consortium and the first cancer center to have an experimental MR-linac system installed for proof-of-principle testing. Mid-2016, the UMC installed its third MR-linac system - to be used for further non-clinical studies, and perhaps ultimately for clinical treatment.
By August 2016, four consortium members had completed or initiated installation of an MR-linac system:
UMC Utrecht (2009, 2014, 2016)
The University of Texas MD Anderson Cancer Center (Houston, US; 2015)
The Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital (Amsterdam, the Netherlands; 2016)
The Institute of Cancer Research, working with its clinical partner The Royal Marsden NHS Foundation Trust (London, UK; 2016).
Plans are underway to install MR-linac systems for evaluation at the remaining consortium members by the end of 2016: Sunnybrook Health Sciences Centre (Toronto, Canada), Froedtert & the Medical College of Wisconsin Froedtert Hospital (Milwaukee, US) and the Christie NHS Foundation Trust (Manchester, UK).
Installation of the MR-linac at the Netherlands Cancer Institute.
Attention in the academic field
The consortium members are currently evaluating the technology and collaborating to establish new clinical protocols and develop methods for data collection and analysis. This is already generating a large amount of new knowledge. At ESTRO 2016, in late April, seven abstracts were presented that had the MR-linac as their focal point. At AAPM 2016, in early August, another 27 abstracts featured this transformative technology. This new data adds to a growing body of more than 55 peer-reviewed journal publications.
For more information
Visit the Elekta MR-linac homepage, which also includes the latest list of scientific publications:
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