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Intrepid interstellar adventurers

It’s the year 3000 and your great, great, great granddaughter is swimming in Kraken Mare, a gigantic lake of liquid methane and ethane, on Saturn’s moon Titan. The low gravity allows her to leap up and out of the water like a dolphin breaching. As she does so, her enormous eyes (inherited from her father, whose family evolved them on dimly lit Mars) peer through the lenses of her thermal suit at the surrounding deep-hulled sailboats zipping along. In the hazy distance, giant server farms pump out their excess heat into the usefully chilly –180 °C surroundings. Inside, trillions of uploaded human consciousnesses do, well, whatever the digital equivalents of brains-in-jars do, I suppose.

This vivid vision of future recreation is just one possibility teased out in the course of science journalist Christopher Wanjek’s enchanting new book, Spacefarers: How Humans Will Settle the Moon, Mars, and Beyond. The work is rich in detail, accessible, refreshingly frank and compellingly written – in fact, I would go as far as to declare it, hands-down, the most enjoyable piece of non-fiction I have read in years. Starting with a captivating review of humanity’s current progress on the path to settling other bodies in the solar system – from geopolitical drivers to financial constraints – Wanjek explores the challenges and motivations of recreating the Earth-like conditions necessary for our survival, out in space and on neighbouring worlds.

Of note is a running (and particularly candid) assessment of NASA’s activities and administrative challenges, which offered much food for thought. Launching from this foundation, the second half of the book sets out to envisage what our future in space might be like. They range from the current interest in returning to the Moon and the challenges of having sex in space – all the way to extracting helium-3 and nitrogen from Uranus to power future fusion reactors and populating the atmospheres of majestically spinning, orbiting cities assembled across the solar system.

It should be said that, for me, Wanjek’s work is stronger when engaging with present-day and historical material. The latter half of Spacefarers is (while no less riveting) obviously speculative, with all the incertitude that such an undertaking makes inherent. There is not a small amount of irony in that Wanjek kicks off the book by criticizing the depictions of space travel in film and, later, the fantasies of some futurists. While I suspect that I shall greet much science fiction now with a more sceptical eye, some of his suggestions (as alluded to above) hardly seem less fantastical.

There were a few aspects of Spacefarers that I did find frustrating. At various points, Wanjek envisages off-world settlements as being appropriate for a certain type of retirement community. Until the final third of the work, however, the reasons to create such a “space Miami” did not seem well articulated – the ultimate rationale seems to be to find a demographic of settler unconcerned by the long-term risks of heightened radiation exposure, the weaker gravity, and potential complications around gestating children.

In the opening chapter, meanwhile, a colourful anecdote about Russia’s first experiment to simulate the psychological and physical impacts of long-term confinement during an interplanetary mission – the usefulness of which was compromised by an episode of drunken fisticuffs and sexual harassment – would have benefitted from a more explicit condemnation of the latter behaviour. That is especially so in the light of the many challenges women face working in STEM fields, not to mention their general side-lining in space programmes to date. Instead, Wanjek immediately notes that a similar experiment conducted almost a decade later, the Mars500 mission, “went more smoothly, as Russia decided to exclude females” – a statement that manages to couple implications of victim-blaming with phrasing many consider to be derogatory as well as grammatically awkward. (Where’s the noun? Are we even talking about humans?)

Similarly, a later joke about the “obscurity” of the Italian Space Agency also read poorly. When added to the awkward implication in the same chapter that “grown men” are only justified in hugging and kissing with “good reason” (that is, celebrating successfully landing tech on Mars), it served to further the unfortunate overall impression that the author’s values might not be quite as progressive as his vision for humanity’s next steps off-world. This may be an accidental misrepresentation in poorly chosen words – and certainly these are minor points in an extensive work – but they sadly detracted from my ability to recommend this book with a total lack of reservation.

2020 Harvard University Press £23.95hb 400pp

White papers: RaySearch Laboratories highlights advances in radiation oncology software

This time we are featuring white papers, case studies and a webinar from RaySearch Laboratories.

The machine learning planning module in RayStation* can generate one or multiple deliverable treatment plans in just minutes. The automated treatment planning method learns from historical patient and plan data, and infers a 3D spatial dose on a new patient geometry. This new approach to planning can improve efficiency, reduce treatment plan variability and facilitate knowledge sharing. The white paper, Machine learning automated treatment planning, introduces RayStation’s machine learning planning module and describes a clinical study on head-and-neck cancer cases conducted at University Medical Center Groningen.

Provision CARES Proton Therapy in Nashville, USA, is the first clinic to connect the oncology information system RayCare* directly to the treatment delivery system, using it to record and verify the treatment sessions. In 2018, Provision also became the first clinic worldwide to use RaySearch software exclusively. In the case study, Optimizing the patient journey with RayCare, the Provision team describe their experience of using RayCare and how the system meets the clinic’s specific needs.

High-quality contours of anatomical structures are a vital aspect of radiation therapy, but the process of manually delineating regions-of-interest is time-consuming and suffers from inter- and intra-practitioner variability. With the automatic tools in RayStation, this process can be greatly simplified. The latest technique is deep-learning segmentation, which is able to learn from an unlimited number of patients and still automatically generate contours of all relevant regions-of-interests in under a minute. This approach, described in the white paper Deep-learning segmentation, provides a highly powerful tool for patient modelling in RayStation.

University Medical Center Groningen (UMCG) has teamed up with RaySearch to evaluate the first fully automated machine learning framework for generating robust treatment plans. The case study, Automated robust planning for IMPT in HN cancer using machine learning, describes the use of machine learning to create robust intensity modulated proton (IMPT) plans for oropharyngeal cancer patients. The robust machine learning planning framework* will be clinically available in the RayStation 10B release in December 2020.

Treatment planning for radiation therapy inevitably involves compromises between dose to the tumour volume and sparing of healthy structures. These trade-offs are conventionally handled using trial and error, where parameters such as objective function weights are adjusted and the treatment plan is reoptimized multiple times. Manual parameter tuning is inefficient, and the quality of the result dependent upon the experience and skill of the treatment planner. The white paper Multi-criteria optimization in RayStation introduces the use of multi-criteria optimization (MCO) in treatment planning to provides a more streamlined and intuitive workflow. With MCO, the clinical plan is selected by continuous navigation over the set of possible plans, enabling clinicians to make informed and structured treatment decisions.

Information systems at hospitals support the collection and communication of everything from patient tracking to billing information and treatment history. Commonly, there are multiple information systems, which should seamlessly communicate with each other to support efficient and safe care by avoiding manual transfer of data between hospital systems. The RayCare oncology information system is designed for integration with external healthcare information systems, such as EPIC. The white paper, RayCare connectivity, explores the integration of RayCare between hospital information systems to support a complete view of the patient’s data for clinicians.

Finally, RaySearch presents the webinar Machine learning in radiation oncology. In this virtual product unveiling for ESTRO 2020, Fredrik Löfman and the machine learning team at RaySearch discuss machine learning, including the deep learning segmentation application, machine learning planning and a brief introduction to RaySearch’s latest innovation, RayIntelligence.

*Subject to regulatory clearance in some markets.

Diamond microscope probes magnetism in 2D materials

Magnetism in two-dimensional materials is difficult to characterize because the materials’ extreme thinness renders conventional techniques ineffective. Researchers in Australia, Russia and China have now used a new method called wide-field nitrogen-vacancy (NV) microscopy to measure the magnetic strength of vanadium triiodide (VI₃), a 2D material that is known to be strongly ferromagnetic in its bulk, 3D form. The technique could also be used to study other 2D magnetic materials – including some possible building blocks for future energy-efficient electronic devices.

An NV microscope is a recently-developed instrument that uses defects in diamond as sensitive probes of weak magnetic fields. It is particularly well-suited for analysing samples of van der Waals materials (that is, materials composed of atomically thin layers that interact with each other via weak van der Waals forces) because it enables researchers to image magnetic domains (microscopic regions in which all magnetic moments point in the same direction) in individual flakes of the material with sub-micron resolution.

NV centres as detectors of weak magnetic fields

In the present study, researchers led by Lloyd Hollenberg of the University of Melbourne used an NV microscope made from a diamond substrate with a surface layer of defects. These defects are known as NV centres, and they occur when adjacent carbon atoms in the diamond lattice are replaced with a nitrogen atom and an empty lattice site. The nitrogen has an extra electron that remains unpaired, and therefore behaves as an isolated spin that can be up, down or a superposition of the two. The state of this spin can be probed by illuminating the diamond with laser light and recording the intensity and “spin-active” frequencies of the fluorescence emitted.

Because NV centres are naturally isolated from their surroundings, the spin state of their electrons is not immediately affected by surrounding thermal fluctuations. They can therefore be used to detect the very weak magnetic fields stemming from nearby electronic or nuclear spins – making them highly sensitive probes of magnetic resonance, capable of monitoring local spin changes in a material over distances of a few tens of nanometres.

Measuring magnetic field behaviour

In their experiments, Hollenberg and colleagues placed their sample of VI₃on top of the NV microscope’s defect layer, excited the NV centres with a laser and used a camera to image the resulting fluorescence. By sweeping the frequency of an applied microwave field across the sample (which they placed in a cryostat so that they could repeat the measurements at temperatures ranging from 4 to 300 K), they obtained what is known as an optically-detected magnetic resonance spectrum for their sample.

When the researchers applied a magnetic field of 0.5 to 1 Tesla perpendicular to their samples (the +z direction) at a temperature of 5 K, they observed complete and abrupt switching of the magnetic field direction in most flakes, with no intermediate partially-reversed state. This ferromagnetism persists down to two atomic layers, while the switching remains abrupt up to 50 K, which is VI₃’s Curie temperature (that is, the temperature at which the bulk material loses its permanent magnetism).

VI₃is a nucleation-type hard ferromagnet

In hard magnetic materials like VI₃, the direction-switching process depends on one of two mechanisms: nucleation or pinning of domain walls. In bulk materials, these mechanisms can normally be distinguished by their initial magnetization curves. These curves are produced by placing a sample of a magnetic material in a magnetic field and measuring how its magnetization increases.

In a nucleation-type magnet, the domain walls move freely. In a pinning-type magnet, as the name suggests, they are constantly being trapped. To determine which type of mechanism was at play in ultrathin VI₃, Hollenberg and colleagues applied short magnetic pulses (around 10 nanoseconds long) in the -z direction to samples that had initially been magnetized in the +z direction and imaged the magnetization in a low magnet field after each pulse.

The results obtained suggest that ultrathin VI₃is a nucleation-type hard ferromagnet. However, the researchers also found that the magnetic strength of 2D VI₃is roughly half that of its 3D counterpart. “This was a bit of a surprise, and we are currently trying to understand why the magnetisation is weaker in 2D, which will be important for applications,” says team member Jean-Philippe Tetienne.

Diamond sensors probe matter at high pressures

According to Artem Oganov of the Skolkovo Institute of Science and Technology in Moscow, the group’s work could lead to new technologies. “Just a few years ago, scientists doubted that two-dimensional-magnets are possible at all,” says Oganov, who was also part of the research team. “With the discovery of two-dimensional ferromagnetic VI₃, a new exciting class of materials emerged. New classes of material always mean that new technologies will appear, both for studying such materials and harnessing their properties.”

Members of the team, who include researchers from the University of Basel, RMIT University, Nanjing University of Posts and Telecommunications, Moscow Institute of Physics and Technology, Northwestern Polytechnical University, and Renmin University of China, say they now plan to use their NV microscope to study other 2D magnetic materials. They report their work in Advanced Materials.

Room-temperature superconductor arrives at last, a dark-matter detector mystery

In this podcast, Ranga Dias talks about research that is described in a paper in Nature. This paper has since been retracted by the journal.

Finding a material that is a superconductor at room temperature has been the Holy Grail of condensed matter physics for over a century. In this episode we meet Ranga Dias of the University of Rochester whose team has created a material that is a superconductor at 15 °C. The only catch is that it has to be squeezed at a pressure of two million atmospheres, and Dias explains how this pressure could be reduced.

The direct detection of dark matter is also worthy of Holy Grail status, which is why particle physicists where thrilled in June 2020 when the XENON1T collaboration reported a mysterious signal in their dark-matter detector. After the announcement, theorists around the world scrambled to make sense of the signal – resulting in five tantalizing explanations being published in the journal Physical Review Letters. One of those papers was from an international team that includes Jayden Newstead of the University of Melbourne, who joins us to talk about what the XENON1T signal could mean.

Meteorite impacts did not magnetize the Moon’s crust, new simulations reveal

A leading theory as to why regions of the Moon’s crust are magnetized has been debunked by researchers in the US, Germany, and Australia. Through a combination of simulation techniques, a team led by Rona Oran at the Massachusetts Institute of Technology concluded that the lunar surface could not have become magnetized following high-velocity meteorite impacts in the distant past.

When the Moon’s surface was first studied in detail 50 years ago during the Apollo missions, researchers discovered regions of magnetization in the lunar crust that spanned hundreds of kilometres. In the decades since, scientists have not been able to provide a conclusive explanation for how these mysterious features formed – which would require the presence of a magnetic field of a strength that does not currently exist on the Moon.

According to the “core dynamo” theory, the rotation and convection of molten metal in the core of the ancient Moon created the required magnetic field a very long time long ago. However, many scientists have remained sceptical of this idea. Another leading theory suggests that sections of the lunar crust were vapourized by the impacts of high-velocity meteorites, releasing dense clouds of plasma. These expanding clouds would then compress and enhance the interplanetary magnetic field and amplify the induced field inside the Moon.

Several simulations

In the new study, Oran’s team put the impact theory to the test using a combination of high-resolution magnetohydrodynamic simulations – which model the coupled interactions between plasmas and magnetic fields – and simulations of the vapour clouds created by the impacts responsible for large craters on the Moon’s surface. By calculating the mass and thermal energy of the vapour emitted in these events, the group determined the extent to which compression of the interplanetary magnetic field could have induced magnetization in the crust.

Oran and colleagues identified several factors – not previously considered – that reduce the overall enhancement of the magnetic field. These include electrically resistive outer layers in the Moon’s upper mantle, which would have removed magnetic energy; a diffusive effect that would have caused the Moon’s internal field to slip around its core; and the pushing away of the compressed interplanetary magnetic field. As a result, they conclude that the fields produced following high-velocity impacts would have been some three orders of magnitude too weak to produce the magnetized regions that we observe today.

The researchers say that their study leaves the core dynamo theory as the only plausible explanation for the magnetized crust. They also suggest that equivalent dynamo mechanisms could be responsible for magnetized crusts on Mercury, as well as many of the solar system’s meteor-forming asteroids.

The research is described in Science Advances.

Molecular shapeshifter: material that gets thicker when stretched

Most materials get thinner when stretched. Take a rubber band, stretch it along its length, and it will shrink in the other two directions, getting narrower and thinner as you pull. But there are types of materials known as ‘auxetics’ that do the opposite: getting thicker when stretched. Human tendons, cat skin and certain types of metal are examples of natural auxetics, which form tiny voids when stretched, lowering the overall density of the material.

Recently, however, a PhD student at the University of Leeds, UK, discovered a new type of auxetic that displays auxetic behaviour at the molecular scale. Watch the video to find out why this liquid-crystal elastomer (LCE) could be more durable than existing auxetics, making it suitable for body armour, car windows and solar cells. For a more detailed scientific description of this new material, read this feature by Helen Gleeson, the physicist who supervised this research.

#BlackInPhysics week set to celebrate Black physicists

What are the aims of #BlackinPhysics week?

Charles Brown (CB): #BlackInPhysics week, which runs from 25 to 31 October, is dedicated to celebrating the contributions that Black physicists make to science and to revealing a more inclusive picture of what a physicist looks like. The aim of the week is to strengthen intra- and inter-generational connections between Black physicists, encourage long-lasting collaborations and further push for supportive environments where current and future Black physicists everywhere can thrive.

How did the idea come about?

Xandria Quichocho (XQ): There are 12 organizers of #BlackInPhysics week and it has been a team effort. The organizing team was inspired by initiatives such as Black Birders Week, #BlackinAstro and #BlackintheIvory, which gave voice to the aggressions, racism and sexism faced by Black academics across the world. Each of these movements lit the kindling that is growing into a larger fire that is saying “I am Black, I am a scientist and my life matters.” We are all living in the middle of a global revolution that is shouting and telling the world that Black Lives Matter. As people who identify as Black, we have been told time and time again to be neutral and objective in our professional workplaces and places of study. But as the news is saturated with the constant injustices and brutality that are happening to Black, Indigenous and people of colour, it is impossible to pretend that we can go into our classrooms, into our labs and ignore what is going in the outside world. For us, it is not just the “outside” – it is our everyday lives.

What inspired you to organize #BlackinPhysics?

Eileen Gonzales (EG): I wanted to be part of something that focused on connecting members of our community, especially helping to link students who may be the only Black physicist at their institution. We all wanted to focus on all aspects of being Black in physics and not just our science. We found there is a lack of these things being addressed specifically for Black physicists in our community. It is either you focus on being Black in physics and showcase the science, or you focus on a workshop targeting, say, impostor syndrome, but it will lack the perspective of a Black person. We wanted to provide a space for conversations like what it is like to deal with impostor syndrome, mental health and advocating for yourself – all through the lens of a Black physicist.

What are the most pressing barriers facing Black physicists?

XQ: “Representation, representation, representation!” is a phrase we’ve all been hearing recently. It is talked about regarding movie casting, television programmes, in board rooms and even children’s programming. A lack of representation for Black, Indigenous and people of colour isn’t just a problem in popular media; it is an issue that persists and exists in physics departments and labs. According to data collected by the American Physical Society from 2006 to 2016, only 4% of BSc physics degrees were earned by students who self-identified as Black or African American. Unfortunately, this number does not include students who identified as Black mixed-race, more than one race including Black, or Afro-Latinx and Afro-Indigenous.

Are the barriers simply a problem with underrepresentation?

XQ: It’s just the beginning of the problem. Academia itself is a barrier to Black physicists. Traditional STEM programmes operate under the flawed myth of the meritocracy – and completely ignore the biases, racism and sexism that Black, Indigenous and people of colour combat every day. The structures in academia and in physics intentionally bar Black students from gaining access to the field or remaining in it once they have broken the glass ceiling. For example, about 1800 physics PhDs were awarded in the US in 2017 alone but this year will see only the 100th Black American woman ever to achieve that feat. However, there has been a shift in these past few months to change this. Universities, national labs and individuals that took part in #ShutDownSTEM and the #Strike4BlackLives over the summer made the first steps towards creating a more equitable and physics field. The American Institute of Physics recently published its extensive and detailed TEAM-UP Report that not only highlights the barriers for Black students in physics but includes real, long-lasting strategies that departments can take to create a safer environment for Black students to thrive in.

We will judge the success by how effective it has been to celebrate the work of Black physicists and whether it has helped to build an engaged community

What events are planned during #BlackInPhysics week?

EG: We will run both professional and social events targeted at Black physics students, postdocs, faculty, industry and the general public. There are panel discussions aimed at specific career stages such as dealing with impostor syndrome and mental health as well as a three-minute thesis competition for PhD students to showcase their work. We will also host six days of social events including an “ask-a-scientist” session for the general public to engage in conversations with Black physicists, a special Halloween Murder Mystery as well as other events to provide a place for the community to network, relax and socialize. Each day will also feature an article by a Black physicist regarding different aspects of our identities [published jointly on the Physics World and Physics Today websites].

What was the reason for splitting up the week in terms of different areas of physics?

CB: Dedicating an entire day to a single area not only allows physicists within that area to learn about each other and form a community, but also to form a community with varied research interests – often a recipe for innovation and breakthrough. Now, if someone wants to learn about the work of Black atomic physicists, they can simply search the hashtag #BlackinAMO on Twitter. Splitting the week by area has the added benefit of helping employers identify and potentially hire for positions. It also allows us to clearly demonstrate the excellent and wide-ranging work that Black physicists do in their respective areas of physics.

How will you know that the week has been a success or had an impact?

CB: We will judge the success by how effective it has been to celebrate the work of Black physicists and whether it has helped to build an engaged community. It is crucial for our success that this work is done in a way that honours Black physicists’ rich set of identities. Black people are not a monolith, and so neither are Black physicists. We are men, women, non-binary, LGBTQ+, disabled, and in these identities we all enrich the physics discipline. We want to see younger Black physicists discovering their unknown peers and near-peers and we want them to interact with, and be inspired by, more senior Black physicists. We want the senior physicists to learn about the young and talented Black physicists for whom they cleared the path. We want Black physicists of all ranks to learn and hone important skills and tools to help them flourish. And, importantly, we want Black physicists spanning different generations to socialize and have fun with each other at the week’s social events. We also want non-scientists and non-physicists to interact with as many Black physicists as possible.

And what about the benefits to the public?

CB: #BlackinPhysics week offers a unique opportunity for the public to engage each other in a way that is atypical, yet beneficial and empowering for all parties involved. For example, the public will be engaged with physics content on social media and will have the ability to speak directly to, and learn from, physicists, thereby increasing scientific literacy. Physicists will also have myriad opportunities to practise presenting their research in concise yet engaging ways to physicists and non-physicists alike.

Do you plan to keep the initiative going?

EG: Yes, it will continue. Part of our mission is to strengthen intergenerational connections between physicists. We hope to encourage the connections made during #BlackInPhysics week and to build new links through our website and on Twitter with additional future events. A longer-term goal we have is to create a database of all Black physicists that can be used for job hiring, presentation invitations and so on.

Do you think the initiative could be mirrored in other countries?

XQ: #BlackInPhysics is a growing international collaboration. While the current organizing team is made of 12 individuals, our nationalities and histories span the globe. One of the amazing things about living in this age of social media is that we can extend the invitation to this event to a global audience. We aren’t using the hashtag, “US Black physicists” or “Black physicists in America” for a reason. #BlackInPhysics is meant for the people of the African diaspora, for immigrants, for Black and African physicists across the world to connect with each other, to build these connections and communities across oceans. #BlackInPhysics week is a part of a global movement of Black scientists coming together to say, “We are here!”

For more details about#BlackInPhysics week, which runs from 25 to 31 October, see www.blackinphysics.org or follow @BlackInPhysics and #BlackInPhysics on Twitter.

Elekta offers ongoing innovation in precision radiation medicine

From software launches to new radiation therapy equipment, Elekta continues to innovate in the field of cancer-treatment technologies. The company has released, acquired and gained regulatory approval for a range of new radiotherapy products over the last 12 months.

What’s new?

In December 2019, Elekta received 510(k) pre-market notification from the US Food and Drug Administration (FDA) for the use of diffusion-weighted imaging (DWI) datasets obtained with the Elekta Unity MR-linac. This approval expanded the clinical utility of Elekta Unity to include biologic assessment of tumour response during therapy, allowing treatment adaptation based, not just on gross anatomic changes, but also on early biologic changes at the cellular level.

DWI works by creating a map of the diffusion of water molecules at the cellular level, which can be processed to generate the apparent diffusion coefficient (ADC). A growing body of evidence shows that changes in ADC within a tumour can provide important insights into an individual’s tumour response. Such insights, which were previously unavailable during radiation treatment, can support further personalization of the radiotherapy regimen by allowing more tailored dose adaptation. Overall, DWI can improve a clinician’s ability to deliver the right dose to the right part of the tumour.

To learn more, check out the business line update from Lionel Hadjabjeda, president, MR-Linac solutions, on Wednesday 28 October at 12.00 p.m. ET.

Elekta’s MOSAIQ Plaza^* is a powerful, comprehensive set of digital tools that connects users to their colleagues, data and patients, throughout the entire patient workflow. This fully integrated software suite helps to drive efficiencies, standardize daily practice and deliver value-based healthcare.

For example, Elekta recently acquired and continued development of the technology behind MOSAIQ Voice, which enables users to work at the speed of their voice. The tool allows clinical tasks in MOSAIQ to be completed via dictation, streamlining documentation and reducing workload.

Another game-changing workflow advancement is MOSAIQ SmartClinic. With a wide range of professionals involved in cancer patient care, MOSAIQ SmartClinic provides a transparent approach to care management, connecting users to the information that they need, whenever and wherever.

To learn more, check out the business line update from Andrew Wilson, president, oncology informatics solutions, on Tuesday 27 October at 12.00 p.m. ET.

Cervical cancer screening, via Pap and HPV tests, has successfully reduced the incidence of cervical cancer via early detection. But for women still confronted with this disease, treatments such as brachytherapy offer a proven way to improve overall survival. In April 2000. Elekta introduced the Geneva brachytherapy applicator. Designed for cervical cancer up to stage IIB, Geneva could help up to 75% of patients with locally advanced cervical cancer.

In mid-July, Geneva received FDA 510(k) clearance. With a comprehensive range of ovoid (13–40 mm) and intrauterine tube (30–80 mm) sizes, in addition to a new interstitial intrauterine tube to expand treatment options after hysterectomy, Geneva can accommodate most female anatomies. Clinicians can now take advantage of a single gynaecological applicator to treat most cervical cancer patients via intracavitary and/or interstitial brachytherapy.

To learn more, check out the business line update from John Lapré, president, brachytherapy solutions, on Tuesday 27 October at 2.00 p.m. ET.

On 12 June, Elekta introduced Leksell Gamma Knife Lightning^**, a treatment optimizer designed to boost Gamma Knife radiosurgery workflows and improve plan quality. Lightning, which has been available commercially since the end of June, enables clinicians to create plans for multiple targets in less than a minute and to include beam-on time as a constraint, greatly reducing overall treatment time.

Gamma Knife Lightning addresses the challenge of increasing automation and speed in the stereotactic radiosurgery workflow, while also ensuring a personalized plan tailored to each patient’s needs. The ability to create multiple plans in less than 60 s will allow physicians to compare plans and select the best option. And by controlling beam-on time, they can develop plans with the most efficient delivery parameters – cutting beam-on time in half compared with manual forward planning.

To learn more, check out the business line update from Verena Schiller, president, neuroscience solutions, on Monday 26 October at 2.00 p.m. ET.

To expand its offering of cloud-based solutions for advanced radiotherapy, in late-August 2019 Elekta acquired ProKnow^*, offering customers access to high-quality, cloud-based, treatment planning analytics. ProKnow can store, navigate and retrieve data in a scalable cloud-based framework that works across all imaging, planning and treatment modalities. A wealth of insight is contained within these data; but without simple, intuitive solutions, it remains locked away. By centralizing data in a secure web-based repository, ProKnow can unlock it and make it accessible, enabling providers to connect to clinical teams anywhere, any time.

To learn more, check out the breakout session presented by Ben Nelms, founder of ProKnow, on Friday 23 October at 2.00 p.m. ET.

In May 2020, Elekta announced its acquisition of Kaiku Health^*, a Finnish company best known for its app that monitors patient-reported outcomes. The Kaiku Health app provides intelligent symptom tracking and management for healthcare providers in routine oncology care and clinical studies. The app screens for patients’ symptoms, notifies the care team on their development and provides personalized support for patients. It is easily implemented into existing hospital information systems and can be integrated with Elekta’s MOSAIQ oncology information system.

Including intelligent patient-monitoring software in the Elekta portfolio supports the company’s oncology informatics strategy. This is a concrete step toward expanding its digital portfolio to further digitally connect customers and their patients.

To learn more, check out the breakout session presented by Vesa Kataja, chief medical officer, Kaiku Health, on Friday 23 October at noon ET.

Virtual presence

With industry events such as the ASTRO Annual Meeting, the SROA Annual Meeting and the ASRT 2020 radiation therapy conference going completely virtual this year, so has Elekta.

For starters, Elekta is partnering with ASTRO for the very first virtual ASTRO experience. Alongside hosting a booth in the virtual exhibit hall, showcasing the abovementioned products, Elekta is running its virtual User Meeting 2020 on 23 October. Attendees at this event will hear from peers, industry experts and Elekta product specialists in a day of learning, networking and interactive product demonstrations.

The User Meeting will conclude with the session, Championing Women & Diversity in Radiation Oncology—A Panel Discussion. This virtual discussion will include five trailblazing professionals: Laura Cervino from Memorial Sloan Kettering Cancer Center; Sandra Hayden from the University of Texas Southwestern Medical Center; Lisa Kachnic from Columbia University Medical Center and the Herbert Irving Comprehensive Cancer Center; Toral Patel from the University of Texas Southwestern Medical Center; and Crystal Seldon from the University of Miami/Jackson Memorial Hospital.

In the afternoon breakout sessions, radiation oncologists and medical physicists will share their experiences of treating patients on the Elekta Unity and implementing an MR-guided radiotherapy programme. In the field of stereotactic radiotherapy, speakers will discuss linac-based stereotactic treatments and strategies for maximizing SRS efficacy and efficiency with the Leksell Gamma Knife Icon. Attendees can also hear presentations on skin brachytherapy, Elekta’s latest digital solutions, and its recent acquisitions: Kaiku Health and ProKnow. There’s also a discussion on the role of education and training in the medical technology industry.

Elekta is also attending the Virtual Annual Meeting of the Society of Radiation Oncology Administrators (SROA). During the meeting, Elekta will participate in a payer trend roundtable, on 27 October at 3.00 p.m. ET, followed by a “Brown bag” webinar at 4.00 p.m. ET, to share how it is innovating personalized care solutions on a global scale.

As a long-time partner of the American Society of Radiologic Technologists (ASRT), Elekta is participating in the educational sessions at the ASRT 2020 radiation therapy conference and will be hosting a virtual booth at the ASRT expo.

Click here for a list of all of Elekta’s virtual events.

^*MOSAIQ Plaza, ProKnow and Kaiku Health are not available in all markets.

^**Leksell Gamma Knife Lightning is not yet commercially available.

Conductive hydrogel could repair damaged peripheral nerves

Conducting polymer hydrogel — A highly flexible and NIR-responsive conducting polymer hydrogel could repair serious injuries to peripheral nerves. (Courtesy: *ACS Nano* 10.1021/acsnano.0c05197 ©2020 American Chemical Society)

Researchers in China have developed a stretchable and conductive hydrogel that they claim could one day be used to repair peripheral nerves – delicate tissues that transmit bioelectrical signals from the brain to the rest of the body in real time. The hydrogel, which has been tested in rats with sciatic nerve injuries, remains electrically conducting when elongated and its conductivity improves when it is illuminated with near-infrared light. These two properties mean that it could be used to treat serious peripheral nerve injury, especially when the missing nerve length exceeds 10 mm.

Flexible electronics has come along in leaps and bounds in the last few decades, allowing bioelectronic materials to be used as artificial tissue in vivo. Hydrogels – 3D polymer networks that can hold a large amount of water – are similar in structure to nerve tissue, and interfacing these materials to living tissue is one of the most important topics in bioelectronics today.

Repairing injured peripheral nerves

Peripheral nerve injury – for example, when a peripheral nerve has been completely severed in an accident – can result in chronic pain, neurological disorders, paralysis and even disability. Such injuries, however, are difficult to treat.

One of the main techniques used to repair injured peripheral nerves is autologous nerve transplantation. This involves removing a section of peripheral nerve from elsewhere in the body and “sewing” it onto the ends of the severed nerve. There are nevertheless some shortcomings associated with this approach, including the fact that the surgery doesn’t always restore nerve function and that multiple follow-up procedures are sometimes required. There is also the risk of painful neuroma (benign growth of nerve tissue) after the operation.

Another technique relies on tissue engineering to restore and repair motor and sensory function of neuronal cells. This method makes use of natural or synthetic materials that can be grafted onto nerve cells together with “supporting” cells, such as mesenchymal stem cells. The problem with this approach is that the grafted nerves recover slowly.

Hydrogel conducts bioelectric signals

The research team – led by Qun-Dong Shen of Nanjing University, Chang-Chun Wang of the Nanjing Institute of Technology and Ze-Zhang Zhu of the Affiliated Drum Tower Hospital of Nanjing University – has now developed an alternative technique. In their work, the researchers made use of a mechanically tough but stretchable conductive hydrogel containing biocompatible polymers: polyacrylamide and conductive polyaniline. These crosslinked polymers boast a 3D microporous network that, once implanted, allows nerve cells to enter and adhere, helping to restore lost tissue.

SEM image — Scanning electron microscopy image of the conductive polymer hydrogel. (Courtesy: *ACS Nano* 2020 10.1021/acsnano.0c05197)

The hydrogel conducts bioelectric signals – something that the team proved by replacing a damaged sciatic nerve from a toad with the material and measuring the signals through it. They also implanted the hydrogel into rats with sciatic nerve injuries. In these experiments, they observed that the rats’ nerves recovered their bioelectrical properties – as measured by electromyography one to eight weeks following the operation – and that their walking improved compared with rats that hadn’t been treated with the hydrogel.

Another advantage of the hydrogel is that the current flowing through it increases from 1.95 nA to 2.3 nA when it is irradiated with near-infrared light, which can penetrate deep into biological tissue. This proves that the hydrogel is relatively sensitive to light of this wavelength, say the researchers, and that the bioelectrical signal through the material can be increased in this way, so allowing for improved nerve conduction and recovery.

And that is not all: when elongated mechanically, the material remains conducting – just like biological nerve tissue. This means that it can accommodate the large strains produced by sutured nerve tissue in motion.

Full details of the research are published in ACS Nano.

‘Quintuple point’ material defies 150-year-old thermodynamics rule

Five different phases of a colloid-polymer mixture can co-exist at the same time, in defiance of the 150-year-old Gibbs phase rule, which states that only three simultaneous phases are possible. The result, which researchers in France and the Netherlands obtained using an algebraic model for the thermodynamics of binary rod-polymer mixtures, could help advance our understanding of phase transitions in complex systems, with possible industrial applications in areas such as food processing and paint manufacture.

The American physicist Josiah Willard Gibbs is an acknowledged founder of modern thermodynamics and physical chemistry. His phase rule, which he derived in the 1870s, sets out the maximum number of different phases that can simultaneously exist in a substance or mixture of substances. For pure substances, Gibbs’ phase rule predicts a maximum of three phases. One well-known example is water, which can co-exist as a liquid, solid and gas at its so-called triple point.

Clustering effect

In the new work, a team led by Remco Tuinier of the Eindhoven University of Technology simulated the behaviour of a colloidal mixture of two particle types – rods and polymers – dispersed in a background solvent. In their computations, they represented rods as hard spherocylinders and the polymers as spheres that freely overlap with each other.

“The system can increase the space available for the polymer chains by clustering the rods together,” Tuinier explains. “This results in a phase separation in the mixture into two (or more) phases containing a phase where the rods are enriched and another area that mainly contains polymers.”

Once this clustering occurs, the heavier rods sink to the bottom of the mixture, leading to segregation. Eventually, the lower part of the mixture becomes so crowded that the rods take up preferential positions so that they are “less in each other’s way”, Tuinier tells Physics World. The rods thus end up neatly arranged next to each other.

A quintuple point emerges

Building on previous models for dispersions of pure rods and disk-polymer mixtures, the researchers developed a quantitative theory to map out a complete phase diagram for their two-component rod-polymer mixtures. According to the calculations of team member Vincent Peters, up to five different phases appear in the system under a specific condition (see image). At this “quintuple point”, the possibilities are an isotropic gas phase with unaligned rods at the top; a nematic liquid crystal phase with rods pointing in roughly the same direction; a smectic liquid crystal phase with rods lying in different layers; and two solid phases with “ordinary” crystals at the bottom.

This five-phase system represents “the first time that the famous Gibbs rule has been broken,” team member Mark Vis says. The profusion of phases is possible, Tuinier adds, because of the shape of the particles (particularly their length and diameter), which Gibbs did not consider. “In addition to the known variables of temperature and pressure, you get two additional variables: the length of the particle in relation to its diameter, and the diameter of the particle in relation to the diameter of other particles in the solution,” he explains.

Serendipitous result

As sometimes happens in science, the result was in part a stroke of luck, since the researchers weren’t initially looking for more than three phases in their simulations. While studying plate-shaped particles and polymers, however, team member Álvaro González García and Vincent Peters observed a four-phase equilibrium. “Álvaro came to me one day and asked me what had gone wrong, because four phases just couldn’t be right,” Tuinier says.

While the team obtained its results using simulations, members say that a real version of their system could easily be produced in the laboratory, and the results tested in experiments. According to Vis, the team’s findings could help advance our understanding of phase transitions in such systems and predict more precisely when phase transitions occur – knowledge that could come in useful for applications such as manufacturing complex colloidal mixtures like mayonnaise or paint.

Liquid crystals in displays could benefit too, Vis adds. “Most industries choose to work with a single-phase system, where there is no segregation,” he says. “But if the exact transitions are clearly described, then the industry can actually use those different phases instead of avoiding them.”

The research is detailed in Physical Review Letters.

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