I thought I was the next James Dyson but my vacuum technology was not disruptive enough! However, in radiotherapy we continue to disrupt current working practices with the latest innovations


I thought I was the next James Dyson but my vacuum technology was not disruptive enough! However, in radiotherapy we continue to disrupt current working practices with the latest innovations.

What is Disruptive Technology? According to Investopedia it is this:

“Disruptive technology is an innovation that significantly alters the way that consumers, industries, or businesses operate. A disruptive technology sweeps away the systems or habits it replaces because it has attributes that are recognizably superior”

Recent disruptive innovations include e-commerce, online news, ride-sharing apps and GPS systems and when introduced, the car, electricity utilities and TV were disruptive technologies.

It should be pointed out that cars were not disruptive to start with as they were too expensive, rare and elite but when Ford brought-out the mass-produced Model T then that changed everything and the horse and cart went into steep decline!

Here are some examples of the most disruptive technologies presently:

Artificial Intelligence

Internet of Things

Space Colonisation

Pic: Will travel to Mars be likely in the next decade?

3D Printing

Medical Innovations including our field of radiotherapy

High-Speed Travel

Robotics

Autonomous vehicles

Advanced VR

Renewable energy

A disruptive technology can be seen to create a “new market and value network” when it eventually disrupts an existing market and value network, sometimes displacing established market-leading firms, products, and alliances. Disruptive innovations tend to be produced by outsiders and entrepreneurs in start-up companies, rather than existing market-leading companies but many things are exceptions to that rule, especially in radiotherapy.

Not in the same league as vacuum supremo James Dyson and certainly not disruptive enough, except to our goods-in department!

Back in 1996 my company DHA invested much time and money in an innovative vacuum bag immobilisation system. The product name INVAC was dreamt up by myself as the vacuum sensing pump technology was originally developed by the Raigmore Hospital in Inverness and an electronics company located on the Moray Firth.

Pic: My system was called Invac, not Henry!

In what I thought was the perfect storm, we already had a vacuum bag supplier based in Dalston in London at a site that made these in a semi-commercial environment. They were assembled by people with learning difficulties while others had mental health and societal issues and funded by a charitable trust and so my involvement was altruistic to a great extent. However, being an entrepreneur a novel turnkey immobilisation system with world-wide sale potential was the obvious next step, well to me anyway!

By combining the supply of ANY user defined shape or size bag, a small compact and quiet vacuum pump to harden the bad, a special storage rack with interconnecting pipes and valves and the vacuum-sensing electronic pump system solved all the problems or so I thought.

The main issue with vacuum bag immobilisation is that following treatment planning and a few treatments the bags can lose their vacuum and allow air in, meaning additional time and money spent on re-simulation or checking of the patients treatment plan and position.

My INVAC system was innovative to the extent that each vacuum bag that was suspended on the special storage rack and connected to the vacuum sensing pump system was monitored for its vacuum level and if air entered, the same amount of air was extracted keeping the bags rock hard and monitored 24/7, happy days!

The system worked well in clinical use in some UK sites and so we undertook to sell the system in the US too! We submitted a very thorough FDA 5(10) k document, that compared what we were doing with similar systems already in clinical use in the US, attended the ASTRO congress in Phoenix to show it, wearing kilts to gain more visitors to our small but very expensive stand and appointed a US sales manager and some dealers. The FDA passed and certified the system and so we were ready to go!

I even met in Cork, Ireland with the then agent and manager of Roy Keane, Irish and Manchester United footballer who was keen to manage the sales and other commercial aspects of this in particular system and other dha proprietary products in Ireland and other countries world-wide.

Pic: Roy Keane’s agent had a desire to sell radiotherapy equipment!

Unfortunately, the people making the bags had less of a desire to see the system succeed as their main focus was to be entertained, fed and watered daily and have some form of job to do to keep them busy and off the streets so returning faulty bags from the US to London was almost impossible to manage when the manufacturing quality control systems failed and the bags returned to us filled our goods-in department, disrupting our offices in a way we hadn’t foreseen.

My desire to be the next James Dyson failed due largely to my altruism, however I did learn a valuable lesson but at some cost!

In radiotherapy the following innovations have largely disrupted the way we work based on my experience to a greater or lesser extent.

Thermoplastic masks, no more plaster casts. Yes-disruptive!

When I was working in the mould room at the Middlesex Hospital, all immobilisation ‘shells’ as they were called then we created by talking a plaster bandage impression, a very messy, hot and claustrophobic process for the patient, which they sometimes refused. This was then filled with plaster of Paris, set and a plastic shell vacuum-formed onto the positive plaster model. This was then essentially fixed to the treatment couch using a special headboard to immobilise the patient and be marked with the beam entry points and field edges.

The innovation from Orfit in the late 80’s to create a thermoplastic mask material from a splinting compound with perforations that was warmed up in water, stretched over the patients that hardened when cooled was truly disruptive for staff and patients alike. There were some issues over the initial accuracy of the mask and its mechanical strength when compared to the “tried and tested” plastic version but that was resolved and now the thermoplastic immobilisation mask is ubiquitous over the whole world.

This was a truly disruptive product and saved on many hours of time to make conventional masks, was better for the patient and staff from a health and safety perspective, well tolerated and with annual incidence of head and neck cancers worldwide more than 550,000 many masks are now made in this way each year.

Pic: Orfit mask

The first ever UK trial started with me at Mount Vernon Hospital and the radiotherapy world has not looked back since. The world-wide spend on radiotherapy equipment is forecast to be around 10.5b USD by 2025 and so thermoplastics for immobilisation is now a multi-million-dollar business in its own right and I’m pleased to have been there at the start even if I didn’t get any company shares!

Orfit along with MacroMedics, Klarity Medical, CIVCO Radiotherapy, Bionix Radiation Therapy, Qfix and others are some of the major suppliers of these products today.

IGRT/IMRT/VMAT are innovative but not really disruptive in the true sense of the word?

I’m not sure that these modalities are disruptive technologies in their own right but Adaptive Radiotherapy on the latest MR Linac certainly is and we’ll come to that later.

We have been using imaging to guide radiotherapy treatment for many years from the early days of port films using simple radiographic plates, electronic portal imaging systems, megavoltage imaging and now cone beam CT. While all these provide a snap shot and moment in time either at the start, during or at the end of a radiotherapy treatment, they are rarely if ever left on dynamically during beam on and so are not truly adaptive in the “dynamic” sense of the word.

As an example, in the early nineties using the Theraplan 500 3D Treatment planning system I was able to upload a series of CT-Scans for a patient we called “Mr EB” who had an oesophageal tumour and by using a novel beams eye view, organ rendering and a block and compensator cutting machine called Autimo 3D and made in Germany by HEK GmbH, I was able to create a completely conformal plan that precisely tracked the tumour for a great length of the oesophagus and deliver that plan using four inhomogeneity based static compensators. This was before the advent of the multi-leaf collimator and sophisticated on board imaging but today at least we would have been able to match and QA on-line these planning scans with a digitally reconstructed radiograph matching planar kV imaging, megavoltage images or cone beam CT!

While larger planning target volume (PTV) margins were used to compensate for localization errors during treatment to reduce impact on healthy tissues they also accounted for geometric uncertainties and patient/organ motion. By improving overall accuracy of radiotherapy through IGRT, PTV’s are decreased reducing dose to surrounding healthy tissues and allowing for increased dose to the tumour and greater local control.

As with Mr EB above, IMRT allows us to create a 3 or 4D plan, specific to the target’s location, shape and motion characteristics with the critical reduction of the PTV margins around the tumour. The ability to avoid more normal tissue and allow for dose escalation added to advances such as respiratory gating allow for a more adaptive approach during treatment.

The addition of surface guided patient positioning and automated patient ID will be looked at later but the ability to remove the need for skin markers, beam entry points and field marking, tattoos and room lasers is further evidence of disruptive innovation in our sector of radiotherapy and cancer treatment. I could discuss other innovative IGRT systems such as the Nomos BAT system using ultrasound, other patient position and organ tracking or gating systems and earlier IMRT devices but have discussed these in previous blogs and so won’t go into these again here.

Tomotherapy in radiotherapy

The TomoTherapy® system was essentially the first complete IGRT/IMRT solution and combined conventional CT imaging with helical treatment delivery. It was extremely innovative but probably not fully disruptive.

The most well-known Tomotherapy system (Tomotherapy is a radiotherapy term, TomoTherapy® is a commercial product) is now made by Accuray in the US and commercial installations began around 2003. The world’s first ‘Tomo’ delivery system was made by Nomos Corporation and delivered in the 90’s and called Corvus which integrated specialised treatment planning with a rotating MiMic style binary MLC system.

However, the use of the low dose 3D CT imaging facility on the TomoTherapy® system is only generally used prior to treatment to assist in the initial patient set-up and so not dynamically adaptive, more an integration of technologies in an easier to use, integrated and innovative product? You can read more here and make up your own mind: www.accuray.com/tomotherapy/

MR-Linac – A disruptive race to the top

ViewRay and Elekta have led the way with the development of the MR Linac. Yes-disruptive!

I should mention right at the start that this blog is not intended to be a technical comparison of these two amazing machines, I would have loved to be a radiographer working on either. I have simply tried to document some of the development time-lines, some of the different features and importantly how the MR-Linac technology will impact on those that operate them.

The innovation in adding a linear accelerator to a MRI scanner is truly disruptive. Its potential impact on patients and staff, working practices and treatment outcomes will likely change the way we perform radiotherapy in a fundamental way. Whether this new machine is the holy grail for our sector and has a far greater impact than proton beam therapy or Flash radiotherapy we’ll see but I am sure it will give these a long run for their money. Current clinical focus seems to be on treating the prostate and pancreas but I am sure that developments will quickly open up further tumour sites.

New working practices mean that radiographers, physicists and clinical oncologists are all required to be present at the time of treatment which is a step change from current practice. This is not an unusual set up for Intra-Operative radiotherapy or IORT however, whereby during surgery this “in theatre MDT” position the IORT field, calculate the treatment plan and deliver the dose all on the fly and so also a “real-time” adaptive treatment.

Treatments with MR Linacs are currently more time consuming than conventional radiotherapy in part due to the additional staffing requirements but also due to the complex contouring/adaptive planning modes, an area that AI and machine learning will likely have an impact on and lower these treatment times considerably.

Additional training in the use and interpretation of MR imaging will be crucial to success but also opens up the possibility of using MR trained diagnostic staff within the radiotherapy treatment process perhaps, something that would no doubt be quite contentious between the powers that be but in an era of staff shortages in radiotherapy, one worth exploring perhaps or a non-starter?

Also, critically and with additional training radiographers could make routine adjustments to the treatment plan dynamically without the need to consult the clinical oncologist, something that is standard practice now on conventional Linacs with on-board imaging where beam positional changes are agreed based on pre-defined or agreed tolerances or distances.

I see that at the Royal Marsden, training for radiographer led contouring and treatment adaption is now being undertaken and so a great start. You can find out more on their new twitter feed here @RM_Radiotherapy.

ViewRay MRIdian

ViewRay began the race to the top in 2012 with the development of their MR guided Cobalt unit. The Barnes-Jewish Hospital in Washington treated the first patient in February 2014.

However, using 3 small but high-activity cobalt sources, all with the usual problematical characteristics of a physical radioactive source, penumbra becomes an issue and so while innovative, the treatment of tumours in the head and neck for example were not always possible and so in 2017 they launched their first MR guided Linac based around the existing product and a 0.35T magnet.

Changing from cobalt to 6MV would have had many challenges such as overcoming the ‘Lorentz effect’ (description later) by putting as many Linac components as great a distance from the isocentre as possible and by shielding the Linac and its subcomponents from the magnetic field. They also committed to field-upgrade existing cobalt-based systems with a Linac, and so likely not without some difficulties.

Pic: Viewray MRIdian system

The Lorentz force explained

Lorentz force is the force exerted on a charged particle q moving with velocity v through an electric field E and magnetic field B. The entire electromagnetic force F on the charged particle is called the Lorentz force (after the Dutch physicist Hendrik A. Lorentz) and is given by F = qE + qv × B.

You can read more here: https://www.britannica.com/science/Lorentz-force

ViewRay solved two of the major long-standing problems to integrate a 6MV photon beam with an MRI system that included the Linac’s radiofrequency interference with the operation of the MRI and secondly MRI based magnetic interference with the operation of the Linac itself as suggested above.

The microwave generated noise created by the Linac is reflected and absorbed so images in principal are as ‘noise-free’ as MRI images as if the Linac wasn’t there!

ViewRay created what they called magnetic ‘shielding-shells’ that create voids in the magnetic field without significantly disturbing the magnetic field used for imaging. This allows the Linac to essentially operate as if there were no magnetic field present. The split design of the magnet assists with this too.

While of course Linac technology obviates the need for the replacement and disposal of Cobalt-60 sources and adoption of associated radiation safety guidelines, in order to overcome any disturbance on the magnetic field, initially Linac based MR‐guided systems have been limited to step‐and‐shoot IMRT but this will change if not already done so.

ViewRay started treating patients in 2017 as this press release from the time describes:

Henry Ford Treats World’s First Patient Using New MRI-Guided Radiation Therapy that Simultaneously Tracks, Treats Tumor

July 19, 2017

DETROIT – The Henry Ford Cancer Institute has treated the world’s first cancer patient today with an advanced radiation therapy that uses an FDA-cleared real-time magnetic resonance imaging and linear accelerator delivery for more precise and accurate radiation treatment.

The MRIdian Linac by ViewRay, Inc. can treat cancer anywhere in the body. It is the world’s first and only FDA-cleared commercially available linear accelerator-based MRI-guided radiation therapy system that can image and treat patients simultaneously. The FDA cleared use of the company’s next generation model in February.

You can read more here: https://www.henryford.com/news/2017/07/viewray-firstpatient

ViewRay term their treatment delivery “MRI-Guided ROAR™” or Real-Time On-Table Adaptive Radiotherapy.

They say that “first pioneered by ViewRay in 2012, MRI-Guided ROAR™ represents a new paradigm in the treatment of cancer, providing clinicians with the ability to improve targeting precision and thus deliver higher, and potentially more effective, radiation doses”.

“Combining the latest innovations in precision radiation delivery with ground-breaking MR image guidance and on-table adaptive therapy, it’s time for the next big advance in radiation oncology”

The ViewRay website is here if you want to find out more: https://viewray.com

Elekta Unity

According to Elekta “Unity is a state-of-the art MR Linac that is setting a new standard for personalized radiation therapy. Elekta Unity provides the ability to reshape the dose based on daily changes in shape, size and position of the tumour and surrounding healthy anatomy and then enables accurate dose delivery with real-time visualization of the tumour”

Pic: Elekta Unity System

Elekta started treating cases just after ViewRay in 2018 as this press release states:

First patient treated with CE-marked Elekta Unity at University Medical Center Utrecht

Milestone heralds the age of personalized and precision radiation medicine for cancer patients in Europe

UTRECHT, The Netherlands, August 22, 2018 – Elekta today announced that the University Medical Center (UMC) Utrecht has started treating cancer patients using a CE-marked, fully-integrated clinical radiation treatment workflow on the company’s high-field magnetic resonance radiation therapy (MR/RT) system, Elekta Unity.

You can read more here: https://www.elekta.com/pressreleases/4D12CB723E319A4F/first-patient-treated-with-ce-marked-elekta-unity-at-university-medical-center-utrecht/

Elekta offer a “scan-plan-treat approach” that supports personalized treatment that meet the unique needs of the individual patients’ anatomy.

They state that they “leverage functional MRI protocols to probe radiobiology and potentially detect/assess tumour response with diagnostic quality imaging provided by the state-of-the-art 1.5T MRI” and that “we needed online, real-time, diagnostic quality MR imaging within the treatment workflow. Elekta Unity is the only system that can provide this.”

The Elekta Unity website is here: https://www.elekta.com/radiotherapy/treatment-delivery-systems/unity/

Which magnet is better? Does it simply boil down to a performance trade-off?

The main difference between the two systems is the magnetic field strength, 0.35 T with ViewRay versus 1.5 T with Elekta. There are likely to be many reasons why there is such a difference, some due to design, some evolutionary, some serendipitous I’m sure.

The MRIdian system utilizes a split, superconducting low field strength magnet that they say helps minimize distortions to the radiation beam and the image so that a precise dose of radiation can be accurately delivered.

Unity is described as the world’s first high-field strength MR-RT delivery system and uses a closed superconducting magnet and so offers very high-quality diagnostic images.

Interference issues can occur which I will try to explain below, directly relating to the magnitude and orientation of the magnetic field when using an integrated linear accelerator in the presence of a strong magnet. The trade-off between “high-field” to improve image quality and “low-field” to minimize electromagnetic interactions and some unwanted dosimetric effects has led to these different designs, each with advantages it seems.

Some say that a lower magnetic field strength may provide benefit in MR‐guided radiotherapy. Spatial integrity, RF field non-uniformity and the impact of the heating of the patient can all impede high-quality imaging.

However, is also often stated that higher magnetic fields universally increase the sensitivity for MRI and so when choosing an MR-Linac there is certainly a trade-off to take into account.

MRI magnets have now reached 7 T for the latest clinical/diagnostic human MRI imaging applications with research and development systems having now reached up to circa 11 T.

Some imaging applications particularly benefit from high magnetic fields through enhanced contrast and so this will eventually extend into radiotherapy when any previous compromise on image quality will no longer be acceptable as it has sometimes been in the past.

I recall the early days of CT-Simulation systems when a wide bore was more important that the number and type of detectors and hence image quality suffered. Things have changed for the better now with advances in on board cone beam technology and the Tomotherapy innovation merging a Linac with a high-quality diagnostic CT scanner system but the journey towards a destination of pure image quality with MR guided radiotherapy likely supersedes this.

Hopefully the manufacturers or my diagnostic peers can comment on the impact of “magnets and T” on our reply forum below or on our social media feeds!

A radiographer’s life, a 40-year career in radiotherapy, what’s next?

I have been lucky to have lived and worked through many advances in radiotherapy over the past 40 years, some disruptive, others not but I know that the changes over the next 10 years will be far greater.

The ability of surface guided radiotherapy or SGRT to essentially set the patient up on the couch for us and then dynamically monitor their position, patient ID systems to check the patients identity automatically and robotic systems to deliver fast, gated and volumetric modulated arc treatments will I fear fully automate radiotherapy at some stage in the future with the addition of AI and machine learning designing highly bespoke treatment plans that are delivered in very quick time.

The role of the therapeutic radiographer will likely morph more into one of overall patient management and merge some parts of the activity of the clinical oncologist with student training adapting to this new era and with qualified radiographers taking more clinically critical decisions before, during and after radiotherapy. Perhaps less technicality and more clinical management will be the key?

However, the recent innovation of FLASH RT with single doses in excess of 600 Gy per second where the Flash effect spares healthy tissue and is now entering pre-clinical trials, is also likely to be a game changer and highly disruptive. Machines using electrons, protons and photons have all been adapted to provide this treatment option and so we will leave this to another blog! Phew!

Duncan Hynd – November 2020 – admin@RadPro.org.uk

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