14 October 2020 · Source: NS Medical Devices · Download PDF

Q&A: The past, present and future of Elekta’s pioneering MR-Linac technology for treating cancer

Hector Ruiz of Elekta discusses how the first MR-Linac was created, the challenges in doing so, and how the technology continues to evolve two years on.

Elekta Unity
Elekta named its MR-Linac 'Unity' due to the fact it combines two technologies - radiotherapy provided by linear accelerator machines, and MR imaging (Credit: Elekta)

With the Covid-19 crisis leading to a backlog of cancer patients – due to many surgical procedures being delayed or postponed – MR-Linac machines like the Elekta Unity may be in higher demand than ever thanks to their ability to treat tumours in a shortened timeframe.

Swedish radiotherapy specialist Elekta became the first company in the world to market an MR-Linac – the Elekta Unity – after receiving FDA clearance in December 2018.

These machines take linear accelerators, or ‘linacs’, which treat cancers by delivering high-energy X-rays to a patient’s tumour, and enhance the images of the human body used during this process with MRI (magnetic resonance imaging) technology.

Despite it still being a relatively new innovation in the field, Elekta’s Unity MR-Linacs are now in use across North America, Europe and Asia, with the company having received at least 80 orders to date from healthcare providers.

And, over the past two years, Elekta has worked to develop this novel technology in order to improve the speed and capability of radiation oncology even further.

Jamie Bell speaks to Hector Ruiz, vice president regional MR-Linac business line, Elekta, to find out everything about the past, present and future of these machines.

Elekta Unity
Hector Ruiz, vice president regional MR-Linac business line, Elekta

Elekta Q&A on MR-Linac technology

Firstly, could you outline Elekta’s history in this field, and how it became the first company to develop a combined MR-Linac machine?

The integrated imaging, treatment delivery and software platform of Elekta Unity was developed by Elekta, which assembled a global consortium in 2012 to help support this ground-breaking development.

The consortium consists of world-leading cancer centres and experts, with Elekta and its MRI technology partner Philips – a leader in diagnostic imaging systems.

The consortium includes researchers in the fields of physics, radiation oncology, radiography, and radiology.

As of mid-2020, the consortium has published more than 265 scientific papers related to Elekta MR-Linac technology, and members have also helped develop the clinical and workflow protocols to ensure seamless integration into existing radiation oncology departments.

For some background, on 19 May 2017, the University Medical Center Utrecht treated its first patient as part of a clinical trial of Elekta’s MR-Linac.

Results of this study were published in November 2017 in Physics in Medicine & Biology.

Elekta’s MR-Linac then received a CE mark in June 2018, and the first patient treatment on a CE-marked Elekta Unity system was completed on 22 August.

In late 2018, the first patients in the United States were treated at the Froedtert & Medical College of Wisconsin Clinical Cancer Center, and the University of Texas MD Anderson Cancer Center.

Why is this combination of technologies important – both for healthcare providers and for patients?

Most radiation treatment systems today utilise cone beam computed tomography [CBCT]. These are like the typical greyscale X-ray images.

Before radiation is delivered, a snapshot X-ray is acquired to evaluate the location of the anatomy, and then radiation is delivered.

Tumours and nearby critical organs are composed of soft tissue, and, while these systems visualise bony anatomy well, their soft tissue characterisation is poor.

Real-time imaging is also impractical, because X-ray delivers ionising radiation to the patient.

So, what would happen if you could guide the treatment with an MRI instead? This is the first and only time a high field diagnostic 1.5 Tesla MRI has been combined with a state-of-the art radiation delivery system.

Therefore, instead of an X-ray snapshot, the clinical team can now acquire an MRI scan before and during the treatment to guide the radiation beam. It’s like going from a point-and-shoot camera to a real-time high definition camcorder.

The combination of an MRI and radiation therapy system was traditionally considered incompatible. The creativity and engineering needed to make these two come together is amazing, which is why we call the product “Unity”.

Elekta Unity
MR-Linac machines make it possible to reduce treatment times from 30 or 40 days, to five days or fewer (Credit: Elekta)

It brings the best of the worlds of radiation oncology and radiology into one system.

In medical devices of any type, the trend is towards “seeing more is better”.

You therefore see robots, navigation systems, and treatment systems that all seek to provide clinicians with more visualisation and more rich data to enable them to make better decisions.

The fields of radiation oncology and radiology both continue to move in this direction, and we believe that the more you can see, the easier it is to deliver a truly personalised treatment for every patient.

It’s all about reducing complications, improving outcomes, and tailoring treatments based on anatomy and biology to deliver personalised precision radiation medicine without compromise. This is why it matters for patients.

For providers, it offers a new clinical paradigm and an opportunity to reduce treatments from 30 or 40 days, down to five days or fewer.

Ancillary procedures, such as the placement of fiducial markers, can be eliminated and they can expand the range of indications they treat with radiation therapy. Both patients and providers benefit here.

What are the real-life benefits when compared with an ordinary linac machine – does it allow anything that was not previously possible in this field?

MR-RT is the name for the new therapeutic method in the industry that combines simultaneous radiation treatment and MRI.

Through the integration of real-time, high-field MR imaging, tumours can be precisely located and have their movement tracked, and treatment delivery can be adapted in real time in response to changes in tumour position, shape, biology and the relationship to sensitive organs over time.

MR-RT provides a radical improvement – the ability to “see while you treat” – which will give clinicians greater confidence that they are precisely targeting the tumour during every treatment session.

This is essential for developing personalised treatment regimens, improving efficacy and reducing the exposure of surrounding healthy tissue to radiation.

Since that principle of combining the two technologies was established, what developments have there been in MR-Linac? One of the biggest changes we’ve seen is in the rapid ramp-up and expanding use of the technology across a wide range of indications.

Early on, customers would start with one or two indications and then broaden their use. With over 20 installations now, the breadth and depth of use has expanded significantly.

The system has been used to treat more than 30 different indications, and customers coming online now have learned from their colleagues’ experience – which means they can ramp-up very quickly.

Our integrated high-field MRI is capable of both, fast anatomical imaging at the same time as treatment delivery and gantry rotation – unlike with low-field MRI – and it also enables functional imaging to be performed during the treatment session.

For example, some customers are acquiring functional scans while they adapt the patient’s treatment plan.

This means they can acquire vast amounts of rich data without adding time to an efficient treatment process. This is a prerequisite for dose painting, in which higher doses of radiation are deposited into the more active areas of tumors.

To enable this important functionality, Elekta opted to add functional imaging techniques, such as diffusion weighted imaging [DWI], to the first commercial release of Unity.

Elekta Unity
Elekta’s MR-Linac technology has been used for a wide range of applications since it was first given regulatory clearance in 2018 (Credit: Elekta)

Functional imaging will enable the acquisition of MR information that is directly related to tissue biology and physiology, and can potentially be regarded as biomarkers that inform the treatment.

DWI is among the most common, studied, and recognised biomarkers that MRI can bring to the radiation therapy arena.

It has been demonstrated in scientific publications that DWI may be used to predict the response of tumors to the radiation treatment, meaning it can discriminate between patients who are responding well to the treatment and those who are not.

This may enable earlier changes to the course of treatment as opposed to waiting weeks until changes are observed – or not – at the anatomical, macroscopic level.

From a technology perspective, Elekta has made enhancements to its MR-Linac technology by adding features for functional and motion-characterisation imaging.

The system is designed to enable acquisition of 4D MRI datasets to analyse and characterise respiration-induced motion. It provides information on the shape and position of anatomical objects in motion, and identifies the dynamic range of motion to help improve RT planning.

The MR-Linac control system has been designed for online adaptive RT and made ready for future real-time adaptive applications. This unprecedented technology is a key differentiator of the MR-Linac system.

Logistically, how were the linac technology and the MRI technology combined?

Normally, the MRI system and the linac are incompatible, because the linac produces a radiofrequency signal that would distort the images. Similarly, the magnetic field would impact the linac’s performance.

The team that brought these together came up with a novel design to bring them together while also keeping them “de-coupled”.

This was achieved through an active shielding mechanism, meaning that the linac gantry, beam-shaping MLC [multileaf collimator] leaves and radiation delivery system can all be moving and performing at the same time without any perturbations to the image quality or to the treatment system.

This means efficient patient throughput and the ability to innovate on top of the existing system infrastructure.

What areas of the world do you predominantly manufacture and provide these machines for, and where does the greatest demand for supply come from?

We manufacture the systems in Crawley, England, and sell them globally where we have regulatory clearance.

We have publicly announced 80 orders for Elekta Unity as of 18 May 2020, for centres in North America, Europe, and Asia.

Recently, Baskent University in Turkey started treating with Elekta Unity and announced that its first patient received stereotactic body radiation therapy [SBRT].

Elekta Unity
Most radiation treatment systems today utilise cone beam computed tomography (CBCT) to view tumours in a patient’s body (Credit: Zhenyu Pan et al.)

This facilitated a five-day treatment versus the 30-40 days that would have been required for conventional radiotherapy, and each treatment session lasted only 35 minutes.

We also announced an expansion of our partnership with GenesisCare earlier this year, in which it will deploy 11 Unity systems into the US market.

We are really grateful for all of our customers around the globe and their monumental efforts to bring this technology to patients, especially in these challenging Covid-19 times.

How has the Covid-19 crisis impacted this technology?

Cancer treatments clearly aren’t elective procedures, and volume at our customers has ramped back up after some initial hits.

The most notable trend is in our customer use and uptake of the technology.

The Elekta Unity MR-Linac is all about hypofractionation – delivering the treatment regimen in a few days versus many weeks.

Patients understand this concept and are requesting this technology because of the precision, personalisation and convenience.

They want to reduce the number of visits to the cancer centre due to the pandemic, and we foresee these trends that were already in progress only accelerating from here.

When it comes to manufacturing these MR-Linac machines, have you experienced any challenges over the past few years with it being such a new technology?

It has indeed been an unprecedented challenge.

I am impressed daily by how the Elekta team rallies across different countries and business lines to keep servicing our customers properly.

We have so many individuals that have gone over and above the call of duty, and there are some remarkable stories that speak to the dedication of our team.

From a supply chain perspective, we have benefitted from our dual-source strategy, with Elekta and our suppliers being designated essential business by relevant government authorities.

Our sites in Beijing and Crawley are fully operational. As far as how we managed, we work as one team, we do what we say, and we keep thinking forward.

We embody these values with customers and supply chain partners to manage the challenges collectively.

Finally, are there any further developments to this technology you are anticipating in the future – either in terms of innovations Elekta is working towards, or wider industry trends?

Elekta has a rich history of innovation and is consistently pushing the field forward.

The technology roadmap for Elekta Unity is incredibly exciting. We are still in the early stages of what the technology can accomplish, yet it has done so much for patients.

We are leveraging our efforts to innovate across our different products and business lines – including linacs, MLC, software, AI and deep learning – to advance the capabilities of Elekta Unity with an objective to further automate tasks and simplify the treatment process.

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