Putting image-guided radiotherapy to the test

Early adopters are exploiting a novel motion phantom to explore the possibilities of real-time magnetic-resonance guided radiotherapy for improved cancer treatment and neurosurgery

Photo of the QUASAR motion phantom from Modus QA — The QUASAR motion phantom from Modus QA allows researchers to explore a range of patient scenarios

Upcoming techniques based on magnetic-resonance guided radiotherapy (MRgRT) could enable clinicians to compensate for patient movements to a much higher degree, thanks to the clarity offered by MR imaging. Real-time tracking methods that can pinpoint changes in the position of a tumour translate to improvements in dose conformality by keeping radiation on target and sparing healthy tissue.

As vendors, early adopters and clinicians bring new ideas to fruition, a key part of their success depends on having the right development tools, which includes motion (or 4D) phantoms. Accurate models give researchers the chance to safely explore solutions for overcoming hurdles that can be faced in the clinic as a result of tumour motion. Scenarios include when a patient breathes, causing organs and tumours to move, or when there’s peristaltic motion through the digestive system.

We’ve designed our system to be compatible and expandable, and even – to a certain degree – customizable

Enzo Barberi, director of MR product development at Modus QA

Tumour movement has always challenged cancer treatment and manufacturers have worked hard to mitigate the issue as much as possible.

“Image guidance for radiation therapy has been around for well over a decade and most linacs have some form of cone-beam CT or EPID imaging that allows to them to roughly see where the target is,” says Enzo Barberi, director of MR product development at Modus QA – a developer and manufacturer of quality assurance tools for advanced radiotherapy and medical imaging. “But those imaging techniques provide little information about soft tissue.”

In contrast, MR imaging can reveal soft tissue in exquisite detail, which – when linked to a radiotherapy system – shines a welcome light on where the cancer is at any moment in time.

Barberi, who’s been working in this field for almost three decades, confirms that it’s a very exciting time in terms of the technology and the clinical development of next-generation techniques exploiting MR linacs. “In both systems that are available today, you can image while you are applying radiation,” he points out.

Real-time imaging hits the target

On-board MR imaging offers numerous possibilities for advancing radiotherapy treatment. For example, if gas happens to pass through the intestinal tract of a patient during radiation treatment, real-time MR imaging can detect whether the tumour has moved. And, if the target is now positioned outside the safety margins, the beam can be turned off until the gas has passed through and the tumour moves back into position.

“It’s a dramatic example of how the combination of these two techniques in parallel and in real-time can make a big difference in terms of accuracy in hitting the target when it’s moving,” Barberi comments. Real-time imaging using MR could also see the end of so-called gating, where patients are required to hold their breath to keep their chest stationary – a development that could speed up treatment as well as reducing discomfort.

Bringing these new techniques into the clinic requires reliable tools for quality assurance (QA). MRI-compatible models make it possible to test the ability of novel imaging sequences to track a wide range of movements – such as those resulting from respiration. Verification is important too.

“Using phantoms like Modus’ programmable QUASAR MRI 4D motion product in combination with dosimetry inserts allows early adopters to calculate and measure the dose that is administered to a moving target and ensure that they are actually hitting this moving target and not the surrounding healthy tissue,” says Barberi.

These early adopters are important beta-testers for Barberi and his team, as they are at the frontier of MRgRT. Users require a phantom design that’s flexible, practical and easy to deploy, allowing them to gather as much data as possible for a range of possible patient scenarios.

“Modus focuses very heavily on workflow as we understand that time on the system is valuable,” Barberi comments. “If we can make our QA tools and QA procedures fast and efficient then sites are not only more likely to use them, but they will also appreciate the fact that we’re not taking up a lot of their magnet and linac time simply for setup or integration or when they have to switch over from one mode of measurement to another.”

Early adopters drive development

Features of the QUASAR motion phantom include a spherical target that can mimic numerous trajectories of a tumour in the body, including those seen during breathing. “We can add not only linear motion in and out of the phantom, but we can also add twist and offset that sphere so that it follows a complex 3D path as time plays out,” Barberi explains.

His team acknowledges that different investigators will have different demands, such as when it comes to dosimetry. “Users may wish to use ion chambers or film dosimetry or 3D gel dosimetry,” Barberi notes. “So we’ve designed our system to be compatible and expandable, and even – to a certain degree – customizable.”

Barberi’s group is already working on a second wave of inserts for the MR-safe motion phantom, thanks to the early-adopter programme. The new inserts will focus not just on soft tissue sites, but also modelling deep organ areas and more complex types of motion.

First UK radiation treatment using MR-guided linac

There is no shortage of challenges coming down the pipeline, but Barberi has a great team and is confident in Modus’ approach – having seen its flagship products develop successfully along a similar path. “Working with many different clinicians, physicists and OEMs over the years, we have families of different inserts that we can draw upon,” he says.

Barberi describes MRgRT as a “game changer”, and companies such as Modus are part of a big global effort to support upcoming advances that serve to accelerate the adoption of MR-linac systems for clinical treatment. Initiatives include STARLIT (System Technologies for Adaptive Real-time MR image-guided Therapies), a consortium developing techniques for next-generation motion compensation that includes two large equipment vendors – Elekta and Philips – along with small- and medium-sized companies and academic centres. “We are also equally proud to be a partner with ViewRay, supporting the requirements of an equally respected vendor, and their early adopting customers,” he says

Original Source: https://physicsworld.com/a/4d-phantom-eases-route-to-adaptive-mr-guided-radiotherapy/

Original Date: Sept 25 2018

Radiation Therapy: Equipment Used by Veterinarians

When many of us think of cancer and how it affects us and the lives we lead we are more often than not picturing human patients however, we are not the only ones that affected by cancer. Today’s post is all about cancer in our pets and how their treatment includes similar treatment plans and medical equipment. Just like in the treatment of cancer within humans, pets use radiation therapy in various forms to shrink and kill tumors.

Radiation therapy delivered to pets can take various forms with the most common form of radiation treatment being delivered via linear accelerators with multi-leaf collimators. The multi-leaf collimator moves while the radiation treatment is on and being delivered to the patient. This allows the radiation therapist to sculpt the treatment around the tumor with very little damage done to cells outside of the area.

Another form of radiation therapy that is used to administer radiation treatment to pets and humans alike is Cyberknife, a linear accelerator that is paired with a robotic arm. This combination allows the machine to move around the patient. The radiation beam is turned off and on and is able to deliver radiation to the tumor from several angles. This ensures that the treatment conforms to the shape of the tumor within your pet.

Treatment can also be delivered through a Tomotherapy machine. A Tomotherapy unit is best described as a mix between a LINAC and CT scanner. It allows an image to be taken of the tumor right before radiation treatment is delivered. The therapist uses the images that are produced to guide radiation treatment to the tumor.

Tumors of the brain are treated with a very specific method of radiation known as the Gamma Knife. The word knife in the name may lead you to believe that cutting is involved however this is not the case. What occurs in Gamma Knife treatment is that very high doses of radiation are delivered to a very specific location on the brain while avoiding normal brain tissue.

As with humans, radiation therapy can be prescribed to pet patients through a variety of methods. One method is known as hyper-fractionated which means that many small doses of radiation are delivered to the pet with the goal being complete eradication of the tumor. This method is most often considered after surgery has been performed when there are small bits of the tumor left behind. Another method is known as hypo-fractionated in which radiation therapists use large doses of radiation in order to treat tumors that cannot be removed through surgery.

A more advanced scheme of delivering radiation treatment are Stereotactic Radiation Therapy, SRT. This includes both SRS, Stereotactic Radiosurgery, and SBRT, Stereotactic Body Radiation Therapy. These methods both deliver high doses of radiation in one, two, or three treatments.

Radparts is the world’s largest independent distributor of OEM replacement parts for Linear Accelerators and Radiation Oncology equipment. Radparts provides high quality, user friendly, low cost parts support for linear accelerators and radiation equipment. More information can be found at https://www.radparts.com/.

Revolutionising radiotherapy with the MR Linac

Joshua Freedman is a third-year PhD student in our Division of Radiotherapy and Imaging. In this blog post, he describes his research to help develop new approaches to support treatment planning and guidance on the MR Linac, a revolutionary new type of radiotherapy machine which is currently being applied for the first time in the UK on patients.

Joshua Freedman with the MR Linac

Image: PhD student Joshua Freedman standing in front of the MR Linac

Approximately 40 per cent of all cancer patients are treated with radiotherapy. It damages cancer cells and stops them from growing or spreading in the body.

In UK hospitals, healthcare professionals currently perform radiotherapy treatment in three main stages: treatment planning, treatment delivery and patient follow-up.

In the treatment planning stage, dosimetrists and physicists carefully design the radiation dose delivery – in terms of both the intensity of X-rays delivered to the tumour site and the shape of the radiation beam, which can be tailored to minimise radiation dose to healthy organs such as the heart, and maximise dose to the tumour sites.

Clinicians use CT (computed tomography) scans of each patient taken beforehand to plan treatment, and then carefully position the patients during treatment so that radiation can be delivered according to the plan.

The treatment course is usually delivered in small rounds of treatment (known as fractions) over a period of several weeks.

Currently, the same radiotherapy treatment plan is used for all fractions, but this approach has setbacks: a patient’s anatomy might undergo slow changes between treatment fractions, for example because of weight-loss or tumour shrinkage.

Another issue is that conventional radiotherapy is not able to fully account for any rapid anatomical changes during treatment delivery, for example, as a result of breathing, or due to bladder filling.

The ICR and The Royal Marsden have delivered the first ever treatment in the UK using a Magnetic Resonance Linear Accelerator (MR Linac) machine.

Real-time imaging

A revolutionary new type of radiotherapy machine – the MR Linac, which combines high-quality magnetic resonance (MR) imaging with radiation delivery – might deliver a solution to these challenges. I have the pleasure of working with the MR Linac for my PhD, which is about to enter its final year.

The MR Linac could potentially precisely locate tumours at the time of treatment, tailor the shape of X-ray beams in real time, and accurately deliver doses of radiation even to tumours that are moving, for example as a patient breathes.

Better-personalised treatment plans using the MR Linac will also help to account for anatomical changes between and during treatment fractions.

The first MR Linac in the UK was recently installed at our partner hospital, The Royal Marsden NHS Foundation Trust, and in a hugely exciting milestone – we have just treated the first patient, after several months of work to prepare and optimise the machine with the help of healthy volunteers who underwent scans to help us test and calibrate the equipment.

In my PhD, I am devising methods to calculate four-dimensional (volumetric space + time) MR imaging for the thorax, which might be employed on the MR Linac to better account for respiratory motion during radiation delivery, for instance in the treatment of lung cancer.

My journey to develop four-dimensional MRI began with an exciting ten-week summer internship in Professor Jeff Bamber’s Ultrasound team, where I was introduced to medical physics and worked on the photoacoustic system.

Shortly afterwards I re-joined the ICR to work with Professor Martin Leach and Professor Uwe Oelfke, in the Division of Radiotherapy and Imaging.

At the ICR we offer clinicians a variety of opportunities – from a taught master’s course in Oncology to fellowships providing protected time for research, and higher research degrees.

Studying at the ICR

I have really enjoyed studying at the ICR due to the immense variety of work on offer.

Some of the highlights of my time studying at the ICR include:

Scanning volunteers and patients on the MR Linac and on diagnostic systems.
Developing new methods to better visualise moving tissues for radiotherapy planning.
Applying state-of-the-art Google software to image reconstruction problems.
Writing journal articles.
Attending various international conferences.

However, my favourite part of studying at the ICR has been working with a brilliant, friendly and supportive team. I have gained so many new skills from working in the Division of Radiotherapy and Imaging and am excited for my final year.

Original Source: https://www.icr.ac.uk/blogs/tales-from-the-lab/page-details/revolutionising-radiotherapy-with-the-mr-linac

Original Date: Sept 25 2018

Written By: Joshua Freedman

October Monthly Specials

General Radiotherapy Machines

The most common machine used to distribute external beam radiotherapy treatment is known as a linear accelerator or LINAC for short. LINAC systems generate high energy x-rays that are carefully aimed at the cancerous tumors. This process is done with much care given to direct the rays in a manner that does as little harm as possible to the healthy tissue surrounding the tumor. Linear accelerators are used to treat cancerous tumors on all areas of the body.

Some LINAC systems that are more advanced have the capability to deliver radiation on or near the surface of the skin. In this type of treatment electrons are used in replacement of high energy x-rays.

Newer linear accelerators have the ability to deliver radiation using Intensity Modulated Radiation Therapy, IMRT. These systems use multi-leaf collimators adjust the shape of the radiation beam to match the shape of the tumor. Without these adjustments LINAC systems would only be able to shoot radiation beams in the shape of a square or rectangle.

Radiographers all have different methods that they use to make sure the radiation treatment is targeting the exact location of the cancerous tumor. In its most fundamental form radiation is just a plain x-ray. Most linear accelerators work through digital imaging where the bottom arm of the machine takes an EPI, electronic portal image, or PI, portal image.

The image is compared by radiographers, to images that were generated during the planning process of your treatment as a type of checks and balances before treatment is delivered. The quantity of images that are taken to compare between depends on the departments protocol for imaging. Different types of radiotherapy treatment machines have an On-Board Imager, OBI, that is comprised of a Kv x-ray and detector. Higher quality images are obtained as a verification which allows for another radiotherapy technique known as Image Guided Radiotherapy, IGRT. With IGRT the accuracy of treatment is improved as daily changes are accounted for such as changes in organ location which can in turn reduce unpleasant side effects.

Electrons are generated and speed up to almost as close to the speed of light using electrical fields. The energy continues to increase until it collides with its intended target and then releases the photon energy. These photons enter the patient in an attempt to break down the DNA cells in the cancerous tumor. Healthy cells are most often able to mend themselves where as the cancerous tumors don’t and eventually die.

Imaging and radiotherapy

The Institute of Cancer Research, London, works at the leading edge of imaging and precision radiotherapy. With state-of-the-art facilities and internationally renowned researchers, we are pioneering technologies to improve the diagnosis and monitoring of cancer, and to guide new forms of precision treatment.

Radiotherapy IMRT

Image: Radiotherapy IMRT (Credit: Jan Chlebik/the ICR)

The ICR and our partner hospital, The Royal Marsden NHS Foundation Trust, have a long track record of practice-changing advances in radiotherapy.

We helped to pioneer image-guided radiation therapy, and a technique called intensity-modulated radiotherapy (IMRT), which shapes the radiation beam to the outline of tumours.

Now we’re going even further, with commitments under our research strategy to do the innovative physics needed to target radiation precisely, and to test out enhanced forms of precision radiotherapy in clinical trials.

The aim is to create new treatments that target tumours with pinpoint accuracy, and minimise the side-effects caused by damage to healthy tissue.

The installation by the ICR and The Royal Marsden of one of the world’s most advanced radiotherapy machines, the MR Linac, gives us the capability to shape a radiotherapy beam to a tumour in real time, even as it moves in the body – for example, as a patient breathes.

At the same time, scientists in the ICR’s Centre for Cancer Imaging are pushing boundaries with the very latest in single and combined imaging technologies to visualise tumours precisely, and study their behaviour, physiology and growth.

Our molecular imaging capabilities are a vital tool in preclinical drug discovery and development. By using imaging in animal studies we can, for example, accurately evaluate whether a cancer drug candidate is hitting its target and having the predicted effect.

In future, doctors could use this information to see if tumours are responding to cancer treatments over time, and to adapt treatment accordingly – without the need for the patient to undergo multiple, uncomfortable biopsies.

Original Source: https://www.icr.ac.uk/our-research/about-our-research/imaging-and-radiotherapy

The Lifespan of a Linear Accelerator Parts

A linear accelerator has a wide range of built-ins that are designed to ensure patients are only given the recommended dose of radiation. The dosage recommended by the physician should never be ignored or changed as each treatment dosage is unique to each patient. Linear accelerators are comprised of several parts and mechanisms that age over time. This article will go over what facilities can expect when it comes to the average lifespan of the parts on LINAC systems, CT scanners, and other radiation oncology devices.

The Lifespan of Linear Accelerator Parts

The lifespan of linear accelerator equipment comes down to two major elements: usage and maintenance. On average medical facilities can expect that large scaled radiation equipment, such as linear accelerators, to last around 5 to 10 years before they begin to break down. Regular maintenance of your LINAC system keeps it running smoother, longer.

Examples of medical equipment lifespans are:

High use parts like Magnetron and iView detectors can last upwards of two to three years and with average use around four to six years.
X-ray tubes with high use last about eighteen months however with low usage can last if four years.
XVI detectors can last up to ten years within linear accelerators that have low usage whereas with high usage XVI parts last around five years.
Thyratron tubes have a lifespan of anywhere between three to five years.

Age and Usage of LINAC Parts

The average life expectancy of most linear accelerator parts depends on the legitimacy of the parts and the amount they are used. There are some parts that need to be replaced yearly with increased use, like the electron gun, however with low usage can last upwards of six years.

Environmental factors cannot be ruled out as it also affects the ion chamber of a linear accelerator, high humidity can cause a reduced lifespan. While an average ion chamber will only need a replacement after four years, one in an environment with high humidity will need a replacement after a year.

When to Replace Aging Parts

Replacing aging parts over time is necessary to avoid causing any damages to the equipment. Some corporation has a habit of considering the price of the equipment and the costs involved in changing the parts over time, and as such delayed the immediate replacement of an overdue or overused equipment. But, this is never a good yardstick of profit maximization, in the long run definitely, a breakdown of significant parts of the system may be disastrous to the equipment.

As a Linear Accelerator stays over time and ages, errors can creep in and this will have an adverse effect on the accuracy of the equipment. It is reasonable to expect a good 5 to 10 years of use out of the linear accelerator, but the maintenance also takes its toll on expenses if it stays much longer.

Companies can often get more usage out of a machine and ensure errors are resolved or controlled just by keeping the software up to date and replacing or upgrading linear accelerator parts as at when needed. Most importantly it is advisable to choose a reputable company to replace your LINAC’s aging parts as the wrong equipment can end up creating more damage to the machine instead of improving its performance. Most companies who sell linear accelerators and parts will have service contracts available that offer varying levels of support.

Insanely Intense X-Ray Lasers Have Recorded Nanoplasma Generation For The First Time

Watching an explosion in super slow motion is what we expect from just about any Hollywood action blockbuster.

But capturing details of an explosion that’s about the same size as a protein? That might not have the same appeal as a Michael Bay movie, but don’t let that fool you. There’s a lot we can learn from the sizzle of a nano-sized bang.

Nanoplasma is exactly what it sounds like – bursts of charged particles contained on a sub-microscopic scale as a nanoparticle disintegrates. Now, for the first time, researchers have used a cutting-edge X-ray laser to watch one in high detail.

X-rays are incredibly useful for studying the world of insanely tiny things. Their tight wavelengths act like thin, sensitive fingers capable of feeling every nook and cranny of objects too small to study with your typical microscope.

Unfortunately, what they promise in detail they lack in subtlety. Hitting a delicate object such as a protein with an X-ray and studying the aftermath is like blindly caressing a snowflake to determine its shape. It can be hard to tell what is authentic and what’s clumsy prodding.

Learning exactly what the brutal stabbing of X-rays does to a crowd of atoms would at least help researchers interpret their results, sifting out the details that are significant from the ones that show blast damage.

We recently reported on US researchers using bursts of light from an X-ray free-electron laser called the Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory to study the ionisation of water.

A pulse of intensely focussed electromagnetic radiation in the X-ray region heated water molecules to a temperature hotter than Earth’s core in 75 femtoseconds, blasting the molecules apart into a soup of charged particles they could examine.

This time, another team of physicists used the Spring-8 Angstrom Compact free electron Laser (SACLA) in Japan to strip apart a few thousand atoms of xenon.

Similar to the LCLS, the SACLA focusses a beam of X-rays onto an area that’s a fraction of the width of a human hair, shining with the brightness of thousands of Suns.

As you might imagine, being hit with such an intense pulse – even if it is for less than 10 quadrillionths of a second – will do more than tickle.

The researchers filled a vacuum chamber with about 5,000 xenon particles and hit them with a pulse of X-rays that lasted less than 10 femtoseconds, causing them to lose electrons and leave behind a variety of positively charged ions.

The aftermath wasn’t up for debate. What they wanted to know was exactly how the atoms lost their electrons. Did they all shake free at once? Was it a progressive reaction?

Hollywood cinematography would use high-speed cameras to capture every glorious detail of an explosion. But femtosecond photography requires some clever thinking.

The team used a bright flash of near infra-red laser light, which was absorbed by particles making up the nanoplasma.

The absorption pattern revealed key details about the variety of positive xenon atoms, from those that had lost just a handful of electrons to some that were stripped of as many as nearly half of their stash.

By repeating the experiment with different intervals between the blast and the ‘photo finish’ infra-red snap-shot, the researchers could shoot a virtual slow-motion scene of xenon nanoplasma formation.

Those details pointed to a specific process of ionisation that was more like a steady electron version of pass-the-parcel than a sudden, chaotic free-for-all of electron flight.

Breaking it down, atoms of xenon transform into a bubble of nanoplasma in stages.

Energy absorption was followed by a small number of xenon atoms shedding electrons. These created zones of positives and negatives that continue to hold the plasma together.

Understanding brief moments of a tiny, contained explosion holds the key to understanding how atoms are arranged when the heat is on.

Applied to more complex systems, it could lead to models that better describe the shapes and arrangements of nanomaterials.

Or, throw in a lens flare or two, and we can one day look forward to a more organic version of Transformers on the small screen.

Original Source: https://www.sciencealert.com/x-ray-free-electron-laser-nanoplasma-analysis-xenon-atoms

Original Date: Aug 8 2018

Written By: MIKE MCRAE

September Monthly Specials!

Preventive Maintenance Increases the Lifespan of LINAC Systems

LINAC systems are just one of the methods that facilities use to administer radiotherapy to patients with cancer. The high cost of this technology necessitates that preventive maintenance be routinely undertaken to extend the life span of linear accelerator parts and other radiation oncology equipment. Linear accelerator parts should be serviced to ensure high quality service delivery to patients. This will go a long way in helping cancer patients to access quality treatment.

The main parts of LINAC systems consist of linear accelerator wave guide and the beam defining system. Other parts include: handle control, couch with controls, touch guard and wall panel to hide stand. Being that it is electrical equipment and it’s in continuous use, the systems will breakdown if not cared for properly which will lead to system breakdown. Therefore, preventive maintenance should be regularly done to ensure that the system works effectively and efficiently. A complex system such as linear accelerators and ct scanners depends on electrical connections, once there is poor connection the machine will malfunction. All parts work in cohesion and if one of them is faulty it will affect other parts.

Linear accelerator parts are expensive and the cost of purchasing a new one is prohibitive. Proper preventive maintenance should be carried out from time to time. Most LINAC systems use water cooling because a constant temperature need to be maintained to ensure harmonious operation. However, there is advanced air-cooled chillers for LINAC cooling. This cooling system is expensive but once it is replaced the system works as if it is a new one.

LINAC parts can be procured from the original equipment manufacturer or through local dealers. There are many advantages to buying parts through companies that offer several parts (and services) instead of a more expensive OEM dealer. Often these companies offer less expensive, refurbished options and OEM parts with warranties. If the parts should malfunction within the period of coverage of warranty, they can help. However, one important decision one must make is that whether one should buy refurbished parts or new OEM parts. Refurbished parts are suitable for repairs and maintenance and the cost is lower than buying new ones. This decision is often mostly decided because of your budget however, just know that refurbished parts are just as reliable and as effective so either way you are getting quality parts.

A lot of factors need to be considered when servicing or maintaining LINAC system. One of such considerations is the response time of maintenance company versus original equipment manufacturer. The response time of maintenance companies tend to be quicker than that of the original manufacturer. Therefore, procuring the service of maintenance company will shorten the downtime of the medical equipment. Associated with this is the high level of expertise of engineers working with servicing and maintenance companies.

In most cases, these engineers were trained by original equipment manufacturers hence, the quality of service delivery. Another advantage of servicing and maintenance of linear accelerator parts is that servicing companies have favorable and flexible contract agreement, and this ensure that servicing of equipment is done comprehensively with minimal costs. This contract agreement includes periodical preventive maintenance without extra costs. Routine service and maintenance of LINAC parts are necessary for optimal functioning of the system and it greatly reduces the amount of downtime of the equipment and elongate its lifespan.

Learn more about Radparts and the variety of services and parts they offer to repair medical equipment including: linear accelerators parts, CT scanners parts, linac parts, and radiation oncology equipment at www.radparts.com. To contact one of our medical equipment repair specialists for parts or service call toll free 877.704.3838 for 24/7/365 support.