physicsworld--2020-10-23--Open-source software detects potential collisions in radiotherapy plans - Physics World

A team at Massachusetts General Hospital ( MGH ) has developed RadCollision – an open-source collision detection tool designed to aid dosimetrists planning photon or proton beam radiotherapy .
When embedded in a treatment planning system ( TPS ) , the modular software platform takes just seconds to automatically calculate whether a gantry head will collide with the patient or treatment couch .
In addition to greatly reducing the need for replanning if a collision is detected during the dry run , the tool helps planners choose optimum and feasible irradiation angles to potentially increase the quality of treatment plans @ @ @ @ @ @ @ the radiotherapy department ’ s medical dosimetrists requested software to eliminate guesswork regarding collision risks .
The dosimetrists previously relied on their experience and intuition to determine which incident beam directions and isocentre positions may be infeasible , a time-consuming and less than optimum process .
“ The frequency of potential collisions in the clinic has been mitigated by rudimentary physical measurements and conservative planning decisions , ” explains co-author Kyla Remillard , a photon dosimetry team leader .
“ Without these steps , potential collisions would be observed more frequently .
However @ @ @ @ @ @ @ setups are identical , and so we say there ’ s an opportunity for improvement.
” Writing in Biomedical Physics & Engineering Express , Remillard and colleagues explain that equipment movement during photon treatments can be considerable , with the treatment head mounted on a rotating gantry and a patient couch rotating around a vertical axis .
Movement during proton therapy is even greater , and therefore more complex to calculate , because the moving snout of the treatment head nozzle supports apertures , compensators and range shifters positioned close to the surface @ @ @ @ @ @ @ with robotic arms can lead to some extra risk of collision when the beam is incident from below .
Collision avoidance is based on a detailed 3D description of static objects in each treatment room , as well as the patient ’ s 3D anatomy , the authors explain .
Current methods of assessing potential collisions include the use of 3D scanners or cameras , patient geometry data from a CT scan , and/or analytic software .
These typically require setup-related costs , especially if a cancer treatment centre uses multiple types of @ @ @ @ @ @ @ vendors include 3D visualization tools for real-time interaction with the delivery machine .
But these are not usually embedded in the planning software and may also add licensing costs .
The free RadCollision software does not require purchase of additional software or hardware , and is easily adaptable by any institution for any type of treatment equipment configuration .
RadCollision relies on an initial 3D modelling of the treatment machine , and optionally incorporates the full patient geometry recorded with any 3D scanner or surface imaging device .
It provides a realistic 3D @ @ @ @ @ @ @ , and its modularity enables the user to add or remove room elements from the 3D visualization .
Other features include the ability to evaluate the independent movement of each treatment room element with real-time feedback , and interactive sliders that help planners choose optimal beam angles .
Users also can choose automatic or visual detection modes , with the latter relying on the planner ’ s ability to assess the collision risk in incomplete patient geometries .
RadCollision can be used as soon as the patient ’ s contour data are added @ @ @ @ @ @ @ and couch model from the active treatment plan .
Dosimetrists may adjust the irradiation settings , after which , the software transforms in real time the regions-of-interest ( ROIs ) corresponding to the treatment machine , calculating any collision ( overlap of ROIs ) with the patient or couch .
Collision reports can be automatically calculated for each beam defined in the plan .
The tool requires an initial setup performed by a hospital ’ s information technology department .
The RadCollision software needs to be embedded into each TPS database ( if @ @ @ @ @ @ @ and a folder ( STL files ) with the 3D models of the machines prepared .
RadCollision is currently limited to use with the RayStation TPS , but versions for use with other commercial TPS are planned , says first author Fernando Hueso-González .
The researchers quantitatively evaluated their software using the RayStation TPS with four patient treatment plans that were found infeasible during previous collision checks by therapists .
The software reported collisions with the couch at similar angles to those reported experimentally .
The team also tested the software with a @ @ @ @ @ @ @ a robotic patient positioning system .
“ In one case , we tested in the RadCollision software a beam where the dosimetrist doubted that there was enough clearance with the toe of a patient ’ s foot .
RadCollision predicted that clearance would be very tight , but the irradiation-optimized TPS was feasible , ” comments Remillard .
“ When we performed a dry run , there was no collision.
” The team note that the reliability of the collision assessment depends upon the accuracy of the input data .
Sources of uncertainty @ @ @ @ @ @ @ , patient motion , CT and/or 3D scan data , and the accuracy of 3D models of the machine and couch .
RadCollision has been created with the hope that it will aid in the development of optimally individualized treatment plans .
“ By providing a real-time assurance that the selected angles do not present a risk of collision , dosimetrists are less likely to shy away from irradiation geometries beneficial from the dose perspective , ” write the authors .
“ RadCollision could be most helpful for clinical cases such as stereotactic @ @ @ @ @ @ @ and prone breast treatments , electron beams , and plans with drastically anterior or posterior isocentres.
” “ We are aware of hospitals in the UK , France , Italy , the Netherlands , Spain and the United States trying out our script , ” Hueso-González tells Physics World .
“ We can ’ t use it yet on a clinical basis here at Mass General because we are awaiting an upgrade of TPS software that will be compatible .
We anticipate starting to use it clinically in January 2021 .
”

Collision prevention (left to right): Kyla Remillard, Fernando Hueso-González and David Craft are three of the four researchers who developed the radiotherapy collision assessment tool. (Courtesy: Kyla Remillard)
A team at Massachusetts General Hospital (MGH) has developed RadCollision – an open-source collision detection tool designed to aid dosimetrists planning photon or proton beam radiotherapy. When embedded in a treatment planning system (TPS), the modular software platform takes just seconds to automatically calculate whether a gantry head will collide with the patient or treatment couch. In addition to greatly reducing the need for replanning if a collision is detected during the dry run, the tool helps planners choose optimum and feasible irradiation angles to potentially increase the quality of treatment plans.
The MGH research initiative began when the radiotherapy department’s medical dosimetrists requested software to eliminate guesswork regarding collision risks. The dosimetrists previously relied on their experience and intuition to determine which incident beam directions and isocentre positions may be infeasible, a time-consuming and less than optimum process.
“The frequency of potential collisions in the clinic has been mitigated by rudimentary physical measurements and conservative planning decisions,” explains co-author Kyla Remillard, a photon dosimetry team leader. “Without these steps, potential collisions would be observed more frequently. However, no two patients’ geometries or setups are identical, and so we say there’s an opportunity for improvement.”
Writing in Biomedical Physics & Engineering Express, Remillard and colleagues explain that equipment movement during photon treatments can be considerable, with the treatment head mounted on a rotating gantry and a patient couch rotating around a vertical axis. Movement during proton therapy is even greater, and therefore more complex to calculate, because the moving snout of the treatment head nozzle supports apertures, compensators and range shifters positioned close to the surface of a patient. Additionally, couches with robotic arms can lead to some extra risk of collision when the beam is incident from below.
Collision avoidance is based on a detailed 3D description of static objects in each treatment room, as well as the patient’s 3D anatomy, the authors explain. Current methods of assessing potential collisions include the use of 3D scanners or cameras, patient geometry data from a CT scan, and/or analytic software. These typically require setup-related costs, especially if a cancer treatment centre uses multiple types of treatment systems and patient couches. Some vendors include 3D visualization tools for real-time interaction with the delivery machine. But these are not usually embedded in the planning software and may also add licensing costs.
The free RadCollision software does not require purchase of additional software or hardware, and is easily adaptable by any institution for any type of treatment equipment configuration. RadCollision relies on an initial 3D modelling of the treatment machine, and optionally incorporates the full patient geometry recorded with any 3D scanner or surface imaging device. It provides a realistic 3D visualization of nozzle, couch and patient, and its modularity enables the user to add or remove room elements from the 3D visualization.
Illustration of a collision between gantry (blue) and couch (green) at a gantry angle of 90° detected in the 3D viewer tab of the RayStation TPS. A collision report warns about a collision of gantry with couch, whereas none is found with the right leg. (Courtesy: Biomed. Phys. Eng. Express 10.1088/2057-1976/aba442)
Other features include the ability to evaluate the independent movement of each treatment room element with real-time feedback, and interactive sliders that help planners choose optimal beam angles. Users also can choose automatic or visual detection modes, with the latter relying on the planner’s ability to assess the collision risk in incomplete patient geometries.
RadCollision can be used as soon as the patient’s contour data are added. The program automatically selects the machine and couch model from the active treatment plan. Dosimetrists may adjust the irradiation settings, after which, the software transforms in real time the regions-of-interest (ROIs) corresponding to the treatment machine, calculating any collision (overlap of ROIs) with the patient or couch. Collision reports can be automatically calculated for each beam defined in the plan.
The tool requires an initial setup performed by a hospital’s information technology department. The RadCollision software needs to be embedded into each TPS database (if more than one TPS is used) and a folder (STL files) with the 3D models of the machines prepared. RadCollision is currently limited to use with the RayStation TPS, but versions for use with other commercial TPS are planned, says first author Fernando Hueso-González.
The researchers quantitatively evaluated their software using the RayStation TPS with four patient treatment plans that were found infeasible during previous collision checks by therapists. The software reported collisions with the couch at similar angles to those reported experimentally. The team also tested the software with a model of a proton treatment room and a robotic patient positioning system.
“In one case, we tested in the RadCollision software a beam where the dosimetrist doubted that there was enough clearance with the toe of a patient’s foot. RadCollision predicted that clearance would be very tight, but the irradiation-optimized TPS was feasible,” comments Remillard. “When we performed a dry run, there was no collision.”
The team note that the reliability of the collision assessment depends upon the accuracy of the input data. Sources of uncertainty include changes in patient anatomy or position, patient motion, CT and/or 3D scan data, and the accuracy of 3D models of the machine and couch.
RadCollision has been created with the hope that it will aid in the development of optimally individualized treatment plans. “By providing a real-time assurance that the selected angles do not present a risk of collision, dosimetrists are less likely to shy away from irradiation geometries beneficial from the dose perspective,” write the authors. “RadCollision could be most helpful for clinical cases such as stereotactic treatments, extremities, partial breast irradiation and prone breast treatments, electron beams, and plans with drastically anterior or posterior isocentres.”
“We are aware of hospitals in the UK, France, Italy, the Netherlands, Spain and the United States trying out our script,” Hueso-González tells Physics World. “We can’t use it yet on a clinical basis here at Mass General because we are awaiting an upgrade of TPS software that will be compatible. We anticipate starting to use it clinically in January 2021.”


physicsworld--2020-10-23--Uncrushable beetle reveals its strengths to scientists - Physics World

The toughening mechanisms that make the diabolical ironclad beetle extremely resistant to crushing have been uncovered by researchers in the US and Japan .
David Kisailus at the University of California , Riverside and colleagues found that interlocking sutures in the exoskeletons of the insects allowed them to stiffen when under stress .
The team then created artificial materials inspired by this design – which could allow engineers to develop better techniques for fastening objects together .
Engineers have a wealth of techniques at their disposal for joining dissimilar materials together : including welding , gluing , and mechanical fastening @ @ @ @ @ @ @ fail when subjugated to crushing and high-stress impacts .
Over many millions of years of evolution , a variety of plant and animal species have found highly sophisticated solutions to this problem .
One particularly striking example is the diabolical ironclad beetle , which inhabits the deserts of southern California .
The secret to the ironclad ’ s toughness lies in its exoskeletal forewings , or elytra , which allow it to easily withstand impacts during attacks from predators .
In their study , Kisailus ’ team studied the properties of the ironclad @ @ @ @ @ @ @ why they are so resistant to crushing .
Firstly , they performed compression tests on exoskeletons of the insects .
As stress increased , they observed the structures becoming stiffer – enabling them to withstand a maximum force close to 39,000 times their own weight .
In the main part of the study , Kisailus and colleagues used high-resolution microscopy – including computerized tomography and scanning electron microscopy – to uncover the multiscale architectures responsible for this stiffening .
Whereas the elytra in most beetles are free to move independently , the team @ @ @ @ @ @ @ that permanently fused both parts of the ironclad ’ s elytra together .
These sutures used interlocking jigsaw-puzzle arrangements of ellipsoidal blades ( see figure : “ Strong bonds ” ) .
Next , the researchers created 3D-printed replicas of these sutures and subjected them to high stresses in the lab .
These tests revealed that the interlocking blades did not suddenly snap at their thinnest points to release stress ; instead , they gave way gradually as the blades split apart into layers , which remained connected by fibre bridges .
This @ @ @ @ @ @ @ .
Finally , Kisailus and colleagues used carbon fibre-reinforced elements to create artificial sutures from interlocking blades .
This enabled them to fuse segments of aircraft made from different materials , without the need for rivets or fasteners – which can fail catastrophically when too much stress is applied .
By clearly demonstrated the superior qualities of their bio-inspired material , the team hopes that their discoveries will lead to tough , impact- and crush-resistant structures for joining dissimilar materials together .
The study is described in Nature .

Under pressure: the diabolical ironclad beetle’s exoskeleton has inspired researchers to create crush-resistant components and architectures. (Courtesy: David Kisailus/UCI)
The toughening mechanisms that make the diabolical ironclad beetle extremely resistant to crushing have been uncovered by researchers in the US and Japan. David Kisailus at the University of California, Riverside and colleagues found that interlocking sutures in the exoskeletons of the insects allowed them to stiffen when under stress. The team then created artificial materials inspired by this design – which could allow engineers to develop better techniques for fastening objects together.
Engineers have a wealth of techniques at their disposal for joining dissimilar materials together: including welding, gluing, and mechanical fastening. However, these joins tend to fail when subjugated to crushing and high-stress impacts. Over many millions of years of evolution, a variety of plant and animal species have found highly sophisticated solutions to this problem. One particularly striking example is the diabolical ironclad beetle, which inhabits the deserts of southern California. The secret to the ironclad’s toughness lies in its exoskeletal forewings, or elytra, which allow it to easily withstand impacts during attacks from predators.
Compression tests
In their study, Kisailus’ team studied the properties of the ironclad’s elytra in detail to understand why they are so resistant to crushing. Firstly, they performed compression tests on exoskeletons of the insects. As stress increased, they observed the structures becoming stiffer – enabling them to withstand a maximum force close to 39,000 times their own weight.
Strong bonds: cross section of the medial suture, where two halves of the diabolical ironclad beetle’s elytra meet, showing the jigsaw puzzle configuration. (Courtesy: Jesus Rivera/UCI)
In the main part of the study, Kisailus and colleagues used high-resolution microscopy – including computerized tomography and scanning electron microscopy – to uncover the multiscale architectures responsible for this stiffening. Whereas the elytra in most beetles are free to move independently, the team’s images revealed unique medial sutures that permanently fused both parts of the ironclad’s elytra together. These sutures used interlocking jigsaw-puzzle arrangements of ellipsoidal blades (see figure: “Strong bonds”).
Next, the researchers created 3D-printed replicas of these sutures and subjected them to high stresses in the lab. These tests revealed that the interlocking blades did not suddenly snap at their thinnest points to release stress; instead, they gave way gradually as the blades split apart into layers, which remained connected by fibre bridges. This meant that mechanical failure could occur gradually.
Finally, Kisailus and colleagues used carbon fibre-reinforced elements to create artificial sutures from interlocking blades. This enabled them to fuse segments of aircraft made from different materials, without the need for rivets or fasteners – which can fail catastrophically when too much stress is applied. By clearly demonstrated the superior qualities of their bio-inspired material, the team hopes that their discoveries will lead to tough, impact- and crush-resistant structures for joining dissimilar materials together.
The study is described in Nature.


physicsworld--2020-10-25--Don’t go boiling mad when you discover these scientific secrets to perfect pasta! - Physics World

Today is World Pasta Day , an annual event celebrating the health benefits of this much-loved food staple .
Originating from the 1995 World Pasta Congress , every 25 October is a chance for pasta producers to show off their products .
But being a science journalist , I wanted to discover how we should be cooking pasta based on scientific principles .
I therefore sought the advice of Dario Bressanini , an Italian chemist who shares food-science tips via his YouTube channel .
Bressanini ’ s curiosity for cooking began while following his mother ’ s recipes during his @ @ @ @ @ @ @ Berkeley .
“ During that year of learning and experiments – with many failures – I began always asking myself ‘ why ?
’ when I read the steps of a recipe , ” he said .
Over the years , Bressanini has honed the art of many recipes , but here ’ s his approach to preparing dried pasta – the base ingredient for many homemade classics .
Standard pasta is made from semolina , the milled flour of durum wheat .
It combines starch with protein in the form of gluten @ @ @ @ @ @ @ , soy or xanthan gum . )
For the best results , Bressanini recommends choosing a pasta with at least 13 % protein content .
Otherwise , too much starch will leach out into the water and it will be difficult to achieve that lovely al dente balance between chewy and firm .
Bring a pan of water to the boil then toss in the pasta .
Keep the pan on the heat until it reaches boiling point again ( about 1 minute ) , stirring to prevent the pasta from clumping together @ @ @ @ @ @ @ cover with a lid and remove from the heat .
Now some of you might be screaming : “ WHAT ARE YOU DOING !
?
SURELY YOU NEED TO COOK PASTA IN BOILING WATER AT 100 °C !
” Well , how come mountaineers are able to cook pasta at an altitude of , say , 5000 m where water ’ s boiling point is just over 83 °C ?
It turns out that a lot us who live at roughly sea level regularly waste energy when cooking .
The key thing is @ @ @ @ @ @ @ from the warm surrounding liquid – which occurs whether or not it ’ s bubbling away like a cauldron .
Indeed , as far back as 1799 , the physicist Benjamin Thompson wrote about some of the fallacies of domestic cooking in his essay “ On the construction of kitchen fire-places and kitchen utensils , together with remarks and observations relating to the various processes of cookery ; and proposals for improving that most useful art ” .
For cooking pasta , water only needs to be roughly 80 °C to allow these @ @ @ @ @ @ @ of water into the pasta pieces , without which the middle would remain uncooked .
Anyone who has soaked dried lentils overnight will know this process happens even with cold water .
Warm water simply speeds things up .
b. Gelatinisation of starch ( above 60 °C ) , in which the intermolecular bonds of starch molecules break down .
In simple terms , the starch grains absorb water and swell , leading to a secondary process that softens the pasta .
c. Denaturation and subsequent coagulation of gluten ( 70–80 °C ) @ @ @ @ @ @ @ pasta lose their natural structure , opening up new binding sites to connect with other denaturated proteins .
It ’ s the same phenomenon you see when poaching an egg and the white transforms from a gloopy mess into a firm , white base .
Your pasta should be ready after roughly 12 minutes , though timings will vary slightly depending on your pasta and specific set up .
Drain the water using a colander and combine with your favourite sauce .
Buon appetito !
So why bother ?
Firstly , that marginal @ @ @ @ @ @ @ will add up over time , especially if you start applying the trick to other food ( though the fuel saving will have a more immediate benefit if you ’ re out walking or hiking with a limited amount of gas ) .
Second , if you ’ re cooking particularly delicate types of pasta , such as paccheri , they are much less likely to break .
But for Bressanini , his main motive is to constantly question what we do in the kitchen .
“ Why do we keep doing something @ @ @ @ @ @ @ .
In these nonsensical days we ’ re all living through , perhaps Bressanini ’ s biggest contribution to the kitchen is a healthy serving of rational thought .

Versatile staple pasta forms the basis of many classic dishes (Courtesy: iStock/Rawf8)
Today is World Pasta Day, an annual event celebrating the health benefits of this much-loved food staple. Originating from the 1995 World Pasta Congress, every 25 October is a chance for pasta producers to show off their products. But being a science journalist, I wanted to discover how we should be cooking pasta based on scientific principles.
Pasta master Dario Bressanini, a chemist with a passion for food science (Courtesy: Dario Bressanini)
I therefore sought the advice of Dario Bressanini, an Italian chemist who shares food-science tips via his YouTube channel. Bressanini’s curiosity for cooking began while following his mother’s recipes during his PhD at the University of California, Berkeley. “During that year of learning and experiments – with many failures – I began always asking myself ‘why?’ when I read the steps of a recipe,” he said.
Over the years, Bressanini has honed the art of many recipes, but here’s his approach to preparing dried pasta – the base ingredient for many homemade classics.
Step 1: Choose good-quality pasta
Standard pasta is made from semolina, the milled flour of durum wheat. It combines starch with protein in the form of gluten (or a substitute such as egg, soy or xanthan gum.) For the best results, Bressanini recommends choosing a pasta with at least 13% protein content. Otherwise, too much starch will leach out into the water and it will be difficult to achieve that lovely al dente balance between chewy and firm.
Step 2: Input energy
Bring a pan of water to the boil then toss in the pasta. Keep the pan on the heat until it reaches boiling point again (about 1 minute), stirring to prevent the pasta from clumping together. Once boiling point is reached, cover with a lid and remove from the heat.
Chef's tip Add salt to taste but do not add oil to the water, which some chefs recommend to prevent pasta from sticking. The side effect is that oil on the pasta surface will diminish its capacity to hold the sauce.
Step 3: Let heat transfer take place
Now some of you might be screaming: “WHAT ARE YOU DOING!? SURELY YOU NEED TO COOK PASTA IN BOILING WATER AT 100 °C!”
Well, how come mountaineers are able to cook pasta at an altitude of, say, 5000 m where water’s boiling point is just over 83 °C? It turns out that a lot us who live at roughly sea level regularly waste energy when cooking.
The key thing is that heat transfers into the cold pasta from the warm surrounding liquid – which occurs whether or not it’s bubbling away like a cauldron. Indeed, as far back as 1799, the physicist Benjamin Thompson wrote about some of the fallacies of domestic cooking in his essay “On the construction of kitchen fire-places and kitchen utensils, together with remarks and observations relating to the various processes of cookery; and proposals for improving that most useful art”.
For cooking pasta, water only needs to be roughly 80 °C to allow these three processes to occur.
a. Diffusion of water into the pasta pieces, without which the middle would remain uncooked. Anyone who has soaked dried lentils overnight will know this process happens even with cold water. Warm water simply speeds things up.
b. Gelatinisation of starch (above 60 °C), in which the intermolecular bonds of starch molecules break down. In simple terms, the starch grains absorb water and swell, leading to a secondary process that softens the pasta.
c. Denaturation and subsequent coagulation of gluten (70–80 °C), where the protein complexes in the pasta lose their natural structure, opening up new binding sites to connect with other denaturated proteins. It’s the same phenomenon you see when poaching an egg and the white transforms from a gloopy mess into a firm, white base.
Chef's tip It is crucial that once the pan has been removed from the stove that you minimise the heat escaping to the surroundings. Use a heavy glass lid and avoid lifting it to stir. Also try to leave the pan in the warmest available place.
Step 4: Eat and enjoy!
Your pasta should be ready after roughly 12 minutes, though timings will vary slightly depending on your pasta and specific set up. Drain the water using a colander and combine with your favourite sauce. Buon appetito!
So why bother? Firstly, that marginal saving on your electricity or gas bill will add up over time, especially if you start applying the trick to other food (though the fuel saving will have a more immediate benefit if you’re out walking or hiking with a limited amount of gas). Second, if you’re cooking particularly delicate types of pasta, such as paccheri, they are much less likely to break.
But for Bressanini, his main motive is to constantly question what we do in the kitchen. “Why do we keep doing something that is useless?” he said. In these nonsensical days we’re all living through, perhaps Bressanini’s biggest contribution to the kitchen is a healthy serving of rational thought.


physicsworld--2020-10-26--New optical connections for trapped ions could lead to better quantum computers - Physics World

An important step towards creating a scalable quantum computer based on trapped ions has been made by two independent research groups in the US and Switzerland .
The teams have developed the optics needed to manipulate multiple trapped ions that are integrated onto single chips .
The first practical implementation of quantum gates – the fundamental components of a quantum computer — was made in 1995 by Chris Monroe and David Wineland at the US National Institute for Standards and Technology in Colorado .
The researchers trapped beryllium ions in a vacuum chamber and controlled their electronic energy levels using @ @ @ @ @ @ @ ions was coupled to their motional state , which – owing to the electromagnetic interaction between ions – made the state of one ion conditional on the state of another .
Since then quantum gates have been created using various other systems as quantum bits ( qubits ) .
These include Rydberg atoms , impurities in diamond and superconducting circuits – the latter being used in state-of-the-art quantum computers built by Google and Intel .
Commenting on superconductor-based systems , Monroe ( now at the University of Maryland , College Park ) says @ @ @ @ @ @ @ to today ’ s computers ] , all of the chips are on a two-dimensional surface and you have to wire them together .
People are familiar with those basic fabrication tools.
” In contrast , he says , trapped-ion qubit technology requires more unfamiliar technology : “ It has lasers , it has optics , it has individual atoms in a vacuum chamber.
” Despite their current popularity , progress has recently slowed in the development of superconducting quantum computers , and some researchers are skeptical they will ever scale to thousands @ @ @ @ @ @ @ because , whereas isolated atoms in free space are guaranteed to be identical by the laws of quantum mechanics and can therefore maintain coherent entangled states reliably , manufactured circuit elements are inherently prone to imperfections and almost impossible to isolate from noise .
Several research groups and commercial companies are therefore focusing on developing the technology needed to scale up trapped-ion systems .
Around 15 years ago , says John Chiaverini of Massachusetts Institute of Technology , researchers began fabricating ion traps on chips .
Mastering this basic technology of holding different @ @ @ @ @ @ @ “ utilize some of the other stuff that the [ semiconductor ] industry has built up over 50 or 60 years and put other things in those ion trap chips , like integrated electronics and integrated photonics , ” he says .
“ That work has really only started in earnest in the last five or six years.
” Now , two papers published side by side in Nature – one from the MIT researchers led by Chiaverini and colleague Jeremy Sage , the other from scientists at ETH Zurich – present complementary @ @ @ @ @ @ @ integrated photonics .
Both teams fabricated waveguides on chips to deliver the light necessary to excite specific transitions in their chosen ions — the ETH Zurich group used calcium and the MIT researchers chose strontium .
Using a commercial foundry , the Swiss group fabricated chips with eight waveguides , allowing them to inject light at the wavelengths necessary for initializing their qubits ( bringing them into the desired states ) and controlling them ( switching between the two states ) .
Their trap holds two ions , and the researchers produced a @ @ @ @ @ @ @ The chip itself needs to be cryogenically cooled and placed in high vacuum to keep the ions in the trap .
This requires quite large apparatus , much as the dilution refrigerator around a superconducting quantum computer is tens of centimetres in scale .
However , ETH Zurich team leader Karan Mehta explains that a multi-qubit processor would only require one cryostat : “ Think about scaling a desktop computer , ” he says , “ It doesn ’ t really matter how big the tower is : it matters how powerful the @ @ @ @ @ @ @ on just one qubit but performed a wider variety of operations .
Using their dedicated research foundry , they produced chips able to carry six different wavelengths of light through four different waveguides , allowing them to ionize a neutral strontium atom , load an ion into the trap and cool it before preparing , controlling and reading out its state .
The need to generate and inject light at specific frequencies is one of principal challenges for integrating photonics into trapped ion quantum computing : “ All the materials systems that people @ @ @ @ @ @ @ past are essentially opaque to the light that we need , ” explains Sage , “ A lot of what we have been working on is to develop high-performance integrated optics that works at the wavelengths required by trapped ion systems.
” The research demonstrates a single trapped ion qubit isolated a fraction of a millimetre above a classical , solid-state control system : “ A lot of people speculating about the feasibility of making a larger quantum system assume that , if it ’ s not solid state , then they can @ @ @ @ @ @ @ s Robert Niffenegger , the paper ’ s first author : “ This is starting to bring those things closer together.
” “ It ’ s a great step , because you don ’ t have to align the laser beams – that ’ s a big deal , ” says Monroe .
“ The next step for both groups – and something the rest of the community really wants to do – is to deploy these techniques in a system and make it reliable .
”

Direct coupling: fibre optics send light directly into the MIT ion-trap chip. When in use, the chip is cryogenically cooled in a vacuum chamber, and waveguides on the chip deliver the light to an ion trapped above the chip's surface. (Courtesy: MIT)
An important step towards creating a scalable quantum computer based on trapped ions has been made by two independent research groups in the US and Switzerland. The teams have developed the optics needed to manipulate multiple trapped ions that are integrated onto single chips.
The first practical implementation of quantum gates – the fundamental components of a quantum computer — was made in 1995 by Chris Monroe and David Wineland at the US National Institute for Standards and Technology in Colorado. The researchers trapped beryllium ions in a vacuum chamber and controlled their electronic energy levels using lasers. The energy level of the ions was coupled to their motional state, which – owing to the electromagnetic interaction between ions – made the state of one ion conditional on the state of another.
Since then quantum gates have been created using various other systems as quantum bits (qubits). These include Rydberg atoms, impurities in diamond and superconducting circuits – the latter being used in state-of-the-art quantum computers built by Google and Intel. Commenting on superconductor-based systems, Monroe (now at the University of Maryland, College Park) says, “They use similar tools [to today’s computers], all of the chips are on a two-dimensional surface and you have to wire them together. People are familiar with those basic fabrication tools.” In contrast, he says, trapped-ion qubit technology requires more unfamiliar technology: “It has lasers, it has optics, it has individual atoms in a vacuum chamber.”
Prone to imperfections
Despite their current popularity, progress has recently slowed in the development of superconducting quantum computers, and some researchers are skeptical they will ever scale to thousands of qubits or beyond. This is because, whereas isolated atoms in free space are guaranteed to be identical by the laws of quantum mechanics and can therefore maintain coherent entangled states reliably, manufactured circuit elements are inherently prone to imperfections and almost impossible to isolate from noise.
Several research groups and commercial companies are therefore focusing on developing the technology needed to scale up trapped-ion systems. Around 15 years ago, says John Chiaverini of Massachusetts Institute of Technology, researchers began fabricating ion traps on chips. Mastering this basic technology of holding different atoms in different places allows researchers to “utilize some of the other stuff that the [semiconductor] industry has built up over 50 or 60 years and put other things in those ion trap chips, like integrated electronics and integrated photonics,” he says. “That work has really only started in earnest in the last five or six years.”
Now, two papers published side by side in Nature – one from the MIT researchers led by Chiaverini and colleague Jeremy Sage, the other from scientists at ETH Zurich – present complementary advances in manipulation of trapped ions using integrated photonics. Both teams fabricated waveguides on chips to deliver the light necessary to excite specific transitions in their chosen ions — the ETH Zurich group used calcium and the MIT researchers chose strontium.
Integrated waveguides: laser light is fed into the ETH chip via the optical fibres on the right. (Courtesy: K Metha/ETH Zurich)
Using a commercial foundry, the Swiss group fabricated chips with eight waveguides, allowing them to inject light at the wavelengths necessary for initializing their qubits (bringing them into the desired states) and controlling them (switching between the two states). Their trap holds two ions, and the researchers produced a quantum gate by entangling their states. The chip itself needs to be cryogenically cooled and placed in high vacuum to keep the ions in the trap. This requires quite large apparatus, much as the dilution refrigerator around a superconducting quantum computer is tens of centimetres in scale. However, ETH Zurich team leader Karan Mehta explains that a multi-qubit processor would only require one cryostat: “Think about scaling a desktop computer,” he says, “It doesn’t really matter how big the tower is: it matters how powerful the processor is.”
The MIT researchers focused on just one qubit but performed a wider variety of operations. Using their dedicated research foundry, they produced chips able to carry six different wavelengths of light through four different waveguides, allowing them to ionize a neutral strontium atom, load an ion into the trap and cool it before preparing, controlling and reading out its state.
Essentially opaque
The need to generate and inject light at specific frequencies is one of principal challenges for integrating photonics into trapped ion quantum computing: “All the materials systems that people have used for integrated photonics in the past are essentially opaque to the light that we need,” explains Sage, “A lot of what we have been working on is to develop high-performance integrated optics that works at the wavelengths required by trapped ion systems.”
The research demonstrates a single trapped ion qubit isolated a fraction of a millimetre above a classical, solid-state control system: “A lot of people speculating about the feasibility of making a larger quantum system assume that, if it’s not solid state, then they can’t,” says MIT’s Robert Niffenegger, the paper’s first author: “This is starting to bring those things closer together.”
“It’s a great step, because you don’t have to align the laser beams – that’s a big deal,” says Monroe. “The next step for both groups – and something the rest of the community really wants to do – is to deploy these techniques in a system and make it reliable.”


physicsworld--2020-10-26--Physics in the pandemic: ‘This coronavirus has created an employment crisis across the country’ - Ph

Physics in the pandemic: ‘This coronavirus has created an employment crisis across the country’ - Physics World

Meenu Stephen is a medical physicist who recently joined the radiological physics department of SMS Medical College and Hospitals in Jaipur , India .
This post is part of a series on how the COVID-19 pandemic is affecting the personal and professional lives of physicists around the world .
If you ’ d like to share your own perspective , please contact us at pwld @ ioppublishing.org .
In February , I had just completed my master ’ s degree in medical physics and an internship at Kidwai Memorial Institute of Oncology , and I was searching for a job @ @ @ @ @ @ @ .
While staying at home I realized several things .
With an increasing number of coronavirus cases , the government locked down transport services , closed all public and private offices and factories , and restricted mobilization .
The use of face masks was promoted , and schools and colleges were closed .
All religious groups were told to cancel gatherings to encourage social distancing and reduce the spread of COVID-19 .
People were only allowed out of their houses to provide essential services or buy essential goods .
Police officers regularly patrolled @ @ @ @ @ @ @ that people stayed apart and to inform people about the importance of social distancing and wearing masks and gloves .
For students at the juncture of their academic career or professional courses , as well as for their parents , the lockdown heightened their anxiety , as it affected their education and job opportunities .
Educational institutes had been forced to depend on online learning .
I was using social media to get connected and communicating via mobile phone .
This lethal coronavirus pandemic has not just created a medical emergency but also @ @ @ @ @ @ @ Since the outbreak of COVID-19 , so many hospitals cancelled job interviews .
They were not ready to employ new staff and were trying to manage with the existing workforce .
The absence of flights , trains and other modes of public transport during the lockdown made it impossible anyway .
Six months after my course completion , two vacancies were advertised for medical physicists at SMS Medical College and Hospitals in Jaipur .
The interview was scheduled for 7 July .
The main problem that I faced was attending the interview on @ @ @ @ @ @ @ transportation during that time .
Travelling from one state to another state was a big deal .
Also , different states had different travel rules according to their current COVID-19 situation .
At that time , the only way to reach Jaipur was by flying .
Airline services were very few and there were so many procedures to carry out to get cleared for interstate travel .
The first mandatory step before flying was to install Aarogya Setu , a central government app that uses location trackers and Bluetooth technology to assess the @ @ @ @ @ @ @ Airlines won ’ t allow passengers on flights if the app shows their status as red .
Temperature checks were carried out at all entry points , and self-check in and remote bag drops were mandated to avoid clustering of people .
On the day of my interview , the hospital administration conducted the interview according to the COVID-19 protocol .
All candidates attended their interviews with face masks and maintained social distancing .
After the interview , I was not able to go back home due to lack of airline services .
@ @ @ @ @ @ @ air travellers coming into the state at that time , all should be home quarantined for 14 days from their date of arrival .
The guidelines stated that all passengers had to register their details with the COVID-19 Jagratha web portal .
After undergoing medical screening for any COVID-19 symptoms , asymptomatic persons must undergo home quarantine .
After reaching home , I was in quarantine for 14 days and my family members were not supposed to visit me .
Health workers used to come to my home every day and inspect everything @ @ @ @ @ @ @ inspections and I was asked to call them for requirements including groceries .
After these days of quarantine , I joined SMS Medical College and Hospitals as a senior demonstrator ( medical physicist ) on 4 August .
The distance from my home in Kannur to Jaipur is nearly 3000 km .
During my initial days at work , one of my major problems was speaking in Hindi , the local language in Jaipur .
My mother tongue is Malayalam and understanding Hindi spoken by people wearing face masks was a challenge .
@ @ @ @ @ @ @ interaction with colleagues and patients improved a lot .
Accommodation , food and daily travel to the department were also concerns , but I found accommodation near to the hospital within a week , which also solved the commuting problem .
The COVID-19 situation has made me more conscious of personal and public hygiene .
The rituals of washing hands and sanitizing things before use , which started as a compulsion , slowly became a habit .
At this time , there are no specific vaccines or treatments for COVID-19 .
However , @ @ @ @ @ @ @ potential treatments .
And WHO is continuously providing updates and necessary information .

Meenu Stephen is a medical physicist who recently joined the radiological physics department of SMS Medical College and Hospitals in Jaipur, India. This post is part of a series on how the COVID-19 pandemic is affecting the personal and professional lives of physicists around the world. If you’d like to share your own perspective, please contact us at pwld@ioppublishing.org.
Meenu Stephen (centre) and colleagues working at SMS Medical College and Hospitals in Jaipur. (Courtesy: Department of Radiological Physics)
In February, I had just completed my master’s degree in medical physics and an internship at Kidwai Memorial Institute of Oncology, and I was searching for a job from my home in Kannur, Kerala.
While staying at home I realized several things. With an increasing number of coronavirus cases, the government locked down transport services, closed all public and private offices and factories, and restricted mobilization. The use of face masks was promoted, and schools and colleges were closed. All religious groups were told to cancel gatherings to encourage social distancing and reduce the spread of COVID-19. People were only allowed out of their houses to provide essential services or buy essential goods. Police officers regularly patrolled public places and markets to make sure that people stayed apart and to inform people about the importance of social distancing and wearing masks and gloves.
For students at the juncture of their academic career or professional courses, as well as for their parents, the lockdown heightened their anxiety, as it affected their education and job opportunities. Educational institutes had been forced to depend on online learning. I was using social media to get connected and communicating via mobile phone.
This lethal coronavirus pandemic has not just created a medical emergency but also an employment crisis across the country. Since the outbreak of COVID-19, so many hospitals cancelled job interviews. They were not ready to employ new staff and were trying to manage with the existing workforce. The absence of flights, trains and other modes of public transport during the lockdown made it impossible anyway.
Six months after my course completion, two vacancies were advertised for medical physicists at SMS Medical College and Hospitals in Jaipur. The interview was scheduled for 7 July. The main problem that I faced was attending the interview on that day as there was no proper transportation during that time. Travelling from one state to another state was a big deal. Also, different states had different travel rules according to their current COVID-19 situation.
At that time, the only way to reach Jaipur was by flying. Airline services were very few and there were so many procedures to carry out to get cleared for interstate travel. The first mandatory step before flying was to install Aarogya Setu, a central government app that uses location trackers and Bluetooth technology to assess the risk of the user catching COVID-19. Airlines won’t allow passengers on flights if the app shows their status as red. Temperature checks were carried out at all entry points, and self-check in and remote bag drops were mandated to avoid clustering of people.
On the day of my interview, the hospital administration conducted the interview according to the COVID-19 protocol. All candidates attended their interviews with face masks and maintained social distancing. After the interview, I was not able to go back home due to lack of airline services.
According to the Kerala government guidelines for air travellers coming into the state at that time, all should be home quarantined for 14 days from their date of arrival. The guidelines stated that all passengers had to register their details with the COVID-19 Jagratha web portal. After undergoing medical screening for any COVID-19 symptoms, asymptomatic persons must undergo home quarantine.
After reaching home, I was in quarantine for 14 days and my family members were not supposed to visit me. Health workers used to come to my home every day and inspect everything. Police officers also visited daily for inspections and I was asked to call them for requirements including groceries. After these days of quarantine, I joined SMS Medical College and Hospitals as a senior demonstrator (medical physicist) on 4 August.
The distance from my home in Kannur to Jaipur is nearly 3000 km. During my initial days at work, one of my major problems was speaking in Hindi, the local language in Jaipur. My mother tongue is Malayalam and understanding Hindi spoken by people wearing face masks was a challenge. With time, I adjusted and my interaction with colleagues and patients improved a lot. Accommodation, food and daily travel to the department were also concerns, but I found accommodation near to the hospital within a week, which also solved the commuting problem.
The COVID-19 situation has made me more conscious of personal and public hygiene. The rituals of washing hands and sanitizing things before use, which started as a compulsion, slowly became a habit. At this time, there are no specific vaccines or treatments for COVID-19. However, there are many ongoing clinical trials evaluating potential treatments. And WHO is continuously providing updates and necessary information.


physicsworld--2020-10-26--Patient QA: prioritizing accuracy, efficiency and throughput in the SRS/SBRT workflow - Physics Worl

Patient QA: prioritizing accuracy, efficiency and throughput in the SRS/SBRT workflow - Physics World

The myQA SRS detector will eliminate patient QA bottlenecks associated with high-precision stereotactic radiosurgery ( SRS ) and stereotactic body radiotherapy ( SBRT ) treatments , allowing medical physicists to compare dose distributions – measured versus calculated – in minutes rather than hours and significantly enhancing patient throughput in the process .
That ’ s the claim of IBA Dosimetry , a German supplier of specialist QA products and services to radiation oncology clinics , ahead of the official unveiling of myQA SRS at the virtual ASTRO 2020 Annual Meeting this week .
For context , SRS has generated significant @ @ @ @ @ @ @ the treatment of single and metastatic tumours in the brain .
By exploiting multiple narrow beams from different directions , SRS is able to deliver conformal , high-dose radiation in one or a few fractions while minimizing collateral damage to surrounding healthy tissue and organs at risk .
Similar progress is evident in the stereotactic treatment of tumours elsewhere in the body – for example , in the lungs , liver and spine , where these techniques are referred to collectively as SBRT .
Notwithstanding the growing clinical adoption of stereotactic treatment systems @ @ @ @ @ @ @ focusing high-dose radiation very precisely on a small lesion and having it fall off as quickly as possible – represents a non-trivial dosimetric and QA challenge for the medical physics team .
Put simply : it ’ s not easy to confirm targeting accuracy and dose-distribution accuracy when the stereotactic treatment volume can be as small as a few millimetres in diameter – and doubly so when the existing QA options for SRS/SBRT are unsatisfactory , claims Sandra Kos , product manager for patient QA solutions at IBA Dosimetry .
“ While film @ @ @ @ @ @ @ resolution , ” she explains , “ it is cumbersome to use , time-consuming and temperamental , owing to the uncertainties in handling , calibration and development .
On the other hand , 2D diode arrays and ion-chamber arrays are able to generate results rapidly , but lack the necessary spatial resolution and error-detection sensitivity for SRS/SBRT QA.
” With myQA SRS , Kos argues , that accuracy versus efficiency trade-off no longer applies .
“ We have created a unique SRS/SBRT QA solution that delivers film-class resolution along with the proven workflow @ @ @ @ @ @ @ that ’ s the back-story , what of the device-level innovation ?
The core sensor in myQA SRS exploits a silicon complementary metal-oxide-semiconductor ( CMOS ) technology platform , which enables a compact design , fast read-out and high pixel density along the x and y coordinates ( with each pixel representing a radiation-sensitive element comprising a photodiode , capacitor and three transistors ) .
All of which yields a significantly enhanced digital detector for stereotactic patient QA .
In the clinic , that patient QA process demands a spatial resolution comparable to @ @ @ @ @ @ @ order to detect and analyse errors in SRS/SBRT treatment plans .
While ion chambers , for example , have a proven QA track-record supporting standard radiotherapy techniques – including intensity-modulated radiation therapy ( IMRT ) and volumetric modulated arc therapy ( VMAT ) – they lack the resolution needed to deal with the extreme dose gradients characteristic of SRS/SBRT beam delivery .
Typical SRS QA detector arrays seen in clinical use today offer a pitch ( distance between measurement points ) of 2.5 mm or larger and have limited field sizes .
In @ @ @ @ @ @ @ necessitates dose interpolation to fill in the “ dead points ” between pixels – estimates that , in turn , can lead to dose-peak errors .
“ With the myQA SRS we can decrease the pitch by a factor of 10 [ versus standard arrays ] and multiply the total number of channels by a factor of 100 , ” explains Arianna Giuliacci , a nuclear engineer who heads up the testing programme for myQA SRS within IBA Dosimetry .
As such , the myQA SRS provides a spatial resolution of 0.4 mm @ @ @ @ @ @ @ a large active area of 12×14 cm2 .
Right now , Giuliacci and her colleagues in Schwarzenbruck , Germany , are focused on physical characterization of the myQA SRS detector versus key performance metrics like thermal stability , measurement precision , reliability and robustness .
Using IBA ’ s in-house clinical set-up , the team has also evaluated dosimetric response of the detector at clinical photon fields and compared performance to ionizing chambers – including measurements of small-field beam output factors and percentage depth-dose curves .
“ In parallel , ” Giuliacci adds @ @ @ @ @ @ @ in a treatment planning system , with subsequent irradiation of clinical plans and gamma analysis yielding high pass rates.
” With the in-house testing programme well advanced and third-party clinical evaluation to follow by year-end , myQA SRS is being lined up for full commercial release in the second quarter of next year .
Even now , though , the potential upsides for clinical end-users are evident .
For starters , the active area of the device ( at 12×14 cm2 ) promises significant time savings in the QA of patients with several @ @ @ @ @ @ @ confirm that planned SRS treatments are delivered accurately versus the complex dose distributions required for single-isocentre , simultaneous irradiation of multiple lesions .
“ There is no need for the physicist to prepare multiple plans or choose which targets they want to QA , as everything can fit in one QA plan and one irradiation session , ” explains Kos .
“ The size of the detector clearly helps to verify mono-isocentric plans with multiple targets.
” Ease of use and reliability also underpin the custom development of a cylindrical SRS/SBRT phantom that @ @ @ @ @ @ @ treatment delivery .
As a result , the combined detector–phantom assembly removes uncertainties in set-up , calibration and QA checks , notes Kos , while the QA plans can be verified and cross-checked independently in the same phantom using the myQA SRS detector , different ionization chambers and film .
At the same time , the detector ’ s wireless Gantry Sensor+ provides accurate measurement of linac rotation angles to support rotational treatment plans .
For Kos , the enhanced capabilities of myQA SRS are part of the bigger picture in which independent @ @ @ @ @ @ @ validation of SRS/SBRT treatments .
“ Independence is a fundamental requirement for successful QA , ” she concludes .
“ We can check patient QA outcomes without being influenced by possible malfunctions in the radiotherapy equipment chain , and we can ensure peace of mind and confidence that our customers are doing QA in the right way.
” As such , myQA SRS is compatible with all commercial SRS/SBRT treatment systems , including C arm , O-shaped or robotic linacs in a range of clinical set-ups .

Developed specifically for verification of stereotactic treatment plans, IBA Dosimetry’s latest innovation in patient quality assurance (QA) combines film-class measurement resolution with the workflow efficiency of a digital detector array
Test schedule: ahead of third-party clinical evaluation later this year, IBA Dosimetry is focusing on physical characterization of the myQA SRS detector versus performance metrics like thermal stability, measurement precision, reliability and robustness. (Courtesy: IBA Dosimetry)
The myQA SRS detector will eliminate patient QA bottlenecks associated with high-precision stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT) treatments, allowing medical physicists to compare dose distributions – measured versus calculated – in minutes rather than hours and significantly enhancing patient throughput in the process. That’s the claim of IBA Dosimetry, a German supplier of specialist QA products and services to radiation oncology clinics, ahead of the official unveiling of myQA SRS at the virtual ASTRO 2020 Annual Meeting this week.
For context, SRS has generated significant traction – and clinical success – in the treatment of single and metastatic tumours in the brain. By exploiting multiple narrow beams from different directions, SRS is able to deliver conformal, high-dose radiation in one or a few fractions while minimizing collateral damage to surrounding healthy tissue and organs at risk. Similar progress is evident in the stereotactic treatment of tumours elsewhere in the body – for example, in the lungs, liver and spine, where these techniques are referred to collectively as SBRT.
Notwithstanding the growing clinical adoption of stereotactic treatment systems, the extreme physics of SRS/SBRT – focusing high-dose radiation very precisely on a small lesion and having it fall off as quickly as possible – represents a non-trivial dosimetric and QA challenge for the medical physics team. Put simply: it’s not easy to confirm targeting accuracy and dose-distribution accuracy when the stereotactic treatment volume can be as small as a few millimetres in diameter – and doubly so when the existing QA options for SRS/SBRT are unsatisfactory, claims Sandra Kos, product manager for patient QA solutions at IBA Dosimetry.
“While film provides excellent precision in terms of dose resolution,” she explains, “it is cumbersome to use, time-consuming and temperamental, owing to the uncertainties in handling, calibration and development. On the other hand, 2D diode arrays and ion-chamber arrays are able to generate results rapidly, but lack the necessary spatial resolution and error-detection sensitivity for SRS/SBRT QA.” With myQA SRS, Kos argues, that accuracy versus efficiency trade-off no longer applies. “We have created a unique SRS/SBRT QA solution that delivers film-class resolution along with the proven workflow efficiency of a digital detector.”
QA reimagined
If that’s the back-story, what of the device-level innovation? The core sensor in myQA SRS exploits a silicon complementary metal-oxide-semiconductor (CMOS) technology platform, which enables a compact design, fast read-out and high pixel density along the x and y coordinates (with each pixel representing a radiation-sensitive element comprising a photodiode, capacitor and three transistors). All of which yields a significantly enhanced digital detector for stereotactic patient QA.
In the clinic, that patient QA process demands a spatial resolution comparable to film (approximately 0.4 mm) in order to detect and analyse errors in SRS/SBRT treatment plans. While ion chambers, for example, have a proven QA track-record supporting standard radiotherapy techniques – including intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) – they lack the resolution needed to deal with the extreme dose gradients characteristic of SRS/SBRT beam delivery.
Typical SRS QA detector arrays seen in clinical use today offer a pitch (distance between measurement points) of 2.5 mm or larger and have limited field sizes. In SRS/SBRT, that granularity is insufficient and necessitates dose interpolation to fill in the “dead points” between pixels – estimates that, in turn, can lead to dose-peak errors. “With the myQA SRS we can decrease the pitch by a factor of 10 [versus standard arrays] and multiply the total number of channels by a factor of 100,” explains Arianna Giuliacci, a nuclear engineer who heads up the testing programme for myQA SRS within IBA Dosimetry. As such, the myQA SRS provides a spatial resolution of 0.4 mm, with more than 100,000 pixels across a large active area of 12×14 cm2.
Right now, Giuliacci and her colleagues in Schwarzenbruck, Germany, are focused on physical characterization of the myQA SRS detector versus key performance metrics like thermal stability, measurement precision, reliability and robustness. Using IBA’s in-house clinical set-up, the team has also evaluated dosimetric response of the detector at clinical photon fields and compared performance to ionizing chambers – including measurements of small-field beam output factors and percentage depth-dose curves. “In parallel,” Giuliacci adds, “we have integrated the detector in a treatment planning system, with subsequent irradiation of clinical plans and gamma analysis yielding high pass rates.”
QA best practice
With the in-house testing programme well advanced and third-party clinical evaluation to follow by year-end, myQA SRS is being lined up for full commercial release in the second quarter of next year. Even now, though, the potential upsides for clinical end-users are evident. For starters, the active area of the device (at 12×14 cm2) promises significant time savings in the QA of patients with several treatment volumes, helping medical physicists to confirm that planned SRS treatments are delivered accurately versus the complex dose distributions required for single-isocentre, simultaneous irradiation of multiple lesions.
“There is no need for the physicist to prepare multiple plans or choose which targets they want to QA, as everything can fit in one QA plan and one irradiation session,” explains Kos. “The size of the detector clearly helps to verify mono-isocentric plans with multiple targets.”
Ease of use and reliability also underpin the custom development of a cylindrical SRS/SBRT phantom that’s compatible with static and rotational treatment delivery. As a result, the combined detector–phantom assembly removes uncertainties in set-up, calibration and QA checks, notes Kos, while the QA plans can be verified and cross-checked independently in the same phantom using the myQA SRS detector, different ionization chambers and film. At the same time, the detector’s wireless Gantry Sensor+ provides accurate measurement of linac rotation angles to support rotational treatment plans.
For Kos, the enhanced capabilities of myQA SRS are part of the bigger picture in which independent QA plays a pivotal role in the validation of SRS/SBRT treatments. “Independence is a fundamental requirement for successful QA,” she concludes. “We can check patient QA outcomes without being influenced by possible malfunctions in the radiotherapy equipment chain, and we can ensure peace of mind and confidence that our customers are doing QA in the right way.”
As such, myQA SRS is compatible with all commercial SRS/SBRT treatment systems, including C arm, O-shaped or robotic linacs in a range of clinical set-ups.
Small-field innovation IBA Dosimetry unveiled its work-in-progress myQA SRS detector at the virtual ASTRO 2020 Annual Meeting this week. (Courtesy: IBA Dosimetry) SRS/SBRT target volumes can be as small as few mm diameter and are treated with field sizes of 1×1 cm2 or less. The myQA SRS detector (shown left, with phantom) uses silicon CMOS technology to measure the dose distribution of such a 1×1 cm2 field with 625 measurement points (illustrated in the visualization, right). The schematic shows there is no need for interpolation between measurement points, ensuring unprecedented accuracy for the high dose gradients typical of SRS/SBRT treatment plans. In addition, the myQA SRS offers more than 100 measurement points for a 5 mm stereotactic cone plan.


physicsworld--2020-10-23--Physics in the pandemic: ‘Moving the International Physicists’ Tournament online was challenging’ -

Physics in the pandemic: ‘Moving the International Physicists’ Tournament online was challenging’ - Physics World

David Collomb is a PhD student at the University of Bath , UK , and is organizer of the International Physicists ’ Tournament This post is part of a series on how the COVID-19 pandemic is affecting the personal and professional lives of physicists around the world .
If you ’ d like to share your own perspective , please contact us at pwld @ ioppublishing.org .
The International Physicists ’ Tournament ( IPT ) is a global competition designed to test the problem-solving and presentation skills of undergraduate students interested in physics .
Following the same format as the @ @ @ @ @ @ @ ) for secondary schools , the IPT involves teams of up to six undergraduates spending nine months solving up to 17 challenging , open-ended and unsolved problems in physics .
The tournament winner is traditionally crowned at a week-long event that takes place at a different location each year .
Previous hosts have included famous institutions such as the Moscow Institute of Physics and Technology ( MIPT ) in Russia , the École Polytechnique Fédérale de Lausanne ( EPFL ) in Switzerland , and Chalmers University of Technology in Sweden .
This year @ @ @ @ @ @ @ be the twelfth ever final , things panned out rather differently .
As with many scientific events , conferences , seminars and trade fairs , it was increasingly looking likely that the IPT would have to moved online due to global restrictions designed to combat the spread of COVID-19 .
And so it was , that after much deliberation on how the pandemic will evolve , the executive team of the IPT decided to replace the physical event with a two-day , online tournament on the weekend of 26–27 September 2020 .
The @ @ @ @ @ @ @ “ physics fights ” .
At the start of each , one team serves as “ reporter ” , with an other as “ opponent ” , and a third holds acting as “ reviewer ” .
The reporter is challenged by the opponent to present their work on one of the problems .
Once presented , the opponent then has to constructively critique the reporter ’ s work .
A debate ensues in which the two teams , with guidance from the reviewer , aim to improve upon the approach proposed by @ @ @ @ @ @ @ , the roles switch and the process repeats until each team has held all roles .
A panel of judges grades each role , giving marks out of 10 .
After a series of fights , the top three teams proceed to a final .
Moving the tournament online was challenging .
Time zones were the first major hurdle , with participants stretching from Columbia to China ( a huge 13-hour difference ) .
We ended up altering the rules to ensure all teams could participate at reasonable times .
We did this @ @ @ @ @ @ @ qualifying fights ( apart from the final ) , which drastically cut the times of each fight .
To allow students from across the world to mingle and mix – one of the unique features of the tournament – we also introduced extra activities and opportunities , including the IPT ’ s first photo competition .
It allowed participants to share their creativity and team camaraderie through submitted photos on social media .
A total of 10 teams took part in the tournament this year , each taking part in three qualifying fights @ @ @ @ @ @ @ race looked close with just eight points separating all teams in the top half of the table .
It was only after the final fight that the top three teams – MIPT ( Russia ) , Kharkiv Karazin National University ( Ukraine ) and Rice University ( US ) – emerged .
Rice was one of two teams to appear for the first time in the tournament , the other being from SNS NUST in Islamabad , Pakistan .
The final itself , which you can watch on YouTube , was a tense @ @ @ @ @ @ @ the Ukraine , with only three points out of a total possible 60 separating them after the three rounds .
Viewers were treated to a presentation by the YouTube science communicator Bruce Yeany , who gave his thoughts on some of the problems he had presented and investigated himself in the past .
In a tense final few moments , the Russian team emerged as the overall winner .
The tournament , however , didn ’ t end on the Sunday .
Recognizing that some teams hadn ’ t been able to hunt @ @ @ @ @ @ @ , the executive committee decided to hold three days of presentations in a traditional conference format .
This allowed teams to present solutions that hadn ’ t been challenged in the tournament , while also giving an opportunity to teams that hadn ’ t been able to take part at all , such as those from Brazil and Poland , to show the fruits of their labours .
The pandemic is one of the strongest challenges faced so far in many of our lives , with much of our ordinary day-to-day happenings being @ @ @ @ @ @ @ grounds .
However , the online IPT revealed the strengths of our ability to innovate and bring people together in the midst of isolation , adding much welcome streams of positivity for physics students across the world .
I would like to give special thanks on behalf of the executive committee to all the participants who took part and presented high quality solutions , and to our jury who volunteered their weekend to provide valuable feedback to the students .
Anyone interested in taking part in future events is welcome to contact the @ @ @ @ @ @

David Collomb is a PhD student at the University of Bath, UK, and is organizer of the International Physicists’ Tournament This post is part of a series on how the COVID-19 pandemic is affecting the personal and professional lives of physicists around the world. If you’d like to share your own perspective, please contact us at pwld@ioppublishing.org.
The International Physicists’ Tournament (IPT) is a global competition designed to test the problem-solving and presentation skills of undergraduate students interested in physics. Following the same format as the International Young Physicists’ Tournament (IYPT) for secondary schools, the IPT involves teams of up to six undergraduates spending nine months solving up to 17 challenging, open-ended and unsolved problems in physics.
The tournament winner is traditionally crowned at a week-long event that takes place at a different location each year. Previous hosts have included famous institutions such as the Moscow Institute of Physics and Technology (MIPT) in Russia, the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, and Chalmers University of Technology in Sweden. This year, however, which was meant to be the twelfth ever final, things panned out rather differently.
Online challenge
As with many scientific events, conferences, seminars and trade fairs, it was increasingly looking likely that the IPT would have to moved online due to global restrictions designed to combat the spread of COVID-19. And so it was, that after much deliberation on how the pandemic will evolve, the executive team of the IPT decided to replace the physical event with a two-day, online tournament on the weekend of 26–27 September 2020.
The tournament usually consists of a series of “physics fights”
The tournament usually consists of a series of “physics fights”. At the start of each, one team serves as “reporter”, with an other as “opponent”, and a third holds acting as “reviewer”. The reporter is challenged by the opponent to present their work on one of the problems. Once presented, the opponent then has to constructively critique the reporter’s work.
A debate ensues in which the two teams, with guidance from the reviewer, aim to improve upon the approach proposed by the reporter. After the first round, the roles switch and the process repeats until each team has held all roles. A panel of judges grades each role, giving marks out of 10. After a series of fights, the top three teams proceed to a final.
A tense affair
Moving the tournament online was challenging. Time zones were the first major hurdle, with participants stretching from Columbia to China (a huge 13-hour difference). We ended up altering the rules to ensure all teams could participate at reasonable times. We did this by removing the reviewer role for all qualifying fights (apart from the final), which drastically cut the times of each fight.
To allow students from across the world to mingle and mix – one of the unique features of the tournament – we also introduced extra activities and opportunities, including the IPT’s first photo competition. It allowed participants to share their creativity and team camaraderie through submitted photos on social media.
A total of 10 teams took part in the tournament this year, each taking part in three qualifying fights. After the first two, the race looked close with just eight points separating all teams in the top half of the table. It was only after the final fight that the top three teams – MIPT (Russia), Kharkiv Karazin National University (Ukraine) and Rice University (US) – emerged. Rice was one of two teams to appear for the first time in the tournament, the other being from SNS NUST in Islamabad, Pakistan.
The final itself, which you can watch on YouTube, was a tense affair between the teams from Russia and the Ukraine, with only three points out of a total possible 60 separating them after the three rounds. Viewers were treated to a presentation by the YouTube science communicator Bruce Yeany, who gave his thoughts on some of the problems he had presented and investigated himself in the past. In a tense final few moments, the Russian team emerged as the overall winner.
Don’t stop us now
The tournament, however, didn’t end on the Sunday. Recognizing that some teams hadn’t been able to hunt for solutions since March due to COVID-19, the executive committee decided to hold three days of presentations in a traditional conference format. This allowed teams to present solutions that hadn’t been challenged in the tournament, while also giving an opportunity to teams that hadn’t been able to take part at all, such as those from Brazil and Poland, to show the fruits of their labours.
The pandemic is one of the strongest challenges faced so far in many of our lives, with much of our ordinary day-to-day happenings being rattled and our future placed on shaky grounds. However, the online IPT revealed the strengths of our ability to innovate and bring people together in the midst of isolation, adding much welcome streams of positivity for physics students across the world.
I would like to give special thanks on behalf of the executive committee to all the participants who took part and presented high quality solutions, and to our jury who volunteered their weekend to provide valuable feedback to the students. Anyone interested in taking part in future events is welcome to contact the executive committee via this link.


physicsworld--2020-10-26--Measures of success: how to thrive as a student in physics - Physics World

For a long time , I used to think success in physics mainly meant winning accolades , getting institutional recognition , and having an ingenious understanding of the subject .
And to some degree , these factors do qualify for what it means to be a successful physics student .
I was the first person in my family to pursue a degree in physics , and in time I realized that my measures of success as a student were completely different from what I expected .
I found that being a successful student actually requires a strong foundational work ethic @ @ @ @ @ @ @ As the only daughter of two immigrant parents , and growing up in a typical Caribbean household , success was the only option .
My grades were always expected to be 95 % or above .
The terms “ I don ’ t know ” and “ I can ’ t ” never existed in my vocabulary , and if I chose to embark on a new task , I was expected to finish it .
My parents are the embodiment of hard work , dedication and a strong work ethic , as @ @ @ @ @ @ @ a better life for themselves in the US .
Their resilience inspired me to be as hard-working , which was an essential factor in my success as a student .
My parents knew my potential to attain the impossible , because they had done the impossible themselves .
When I decided to pursue physics as one of my majors at Mount Holyoke College , although my parents were unfamiliar with the subject , they were completely supportive of my decision .
They became my emotional support in the mornings when I had to @ @ @ @ @ @ @ provided a listening ear at night when I felt hopeless and lost about taking courses out of my league , such as electromagnetic theory or quantum mechanics ; and were my biggest fans when I graduated from college magna cum laude .
I was a successful student because of them – their unconditional support , love and work ethic led me to graduate with high honours in physics ; write a senior thesis ; and advocate for resources that were conducive to my well-being as a Black woman in physics .
If physics @ @ @ @ @ @ @ s determination .
I learned from early on that it is not an easy subject .
For many Black students , when we first begin studying physics , we are often reminded that we are seeing and learning this material for the first time .
We recognize and know that the culture , vernacular and coursework of physics disregard the vocabulary and syntax used throughout the Black community .
Physics ’ academic culture does not mirror the multifaceted identities of its Black students – rather , it exists in a world where Black @ @ @ @ @ @ @ learning or becoming familiar with the material at a young age .
Therefore , it usually takes us twice as long and requires twice the effort to complete assignments or gain a basic understanding of the subject .
When I find myself in these situations , struggling to keep up , I remind myself of the reasons I fell in love with physics : attending the free science museum days and learning about the solar system , or riding the subway system in New York and wondering how the trains worked .
The @ @ @ @ @ @ @ my success as a student .
While I never noticed that I was often the only Black girl running around the science exhibits , I remember how tenacious I felt doing physics and how determined I was to find the answers to every scientific question that I asked .
As a student , I made sure to hold on to those same skill sets that I had developed as a child , which included having a natural inclination to wonder about the world and a genuine interest in scientific investigation .
However , @ @ @ @ @ @ @ a student is my community .
That includes friends and other Black physicists who I have collaborated with and learned from along the way .
Their support allowed me to see how I was impacting my community in real time .
Towards the end of my undergraduate experience was the first time I felt I had finally found my place as a physics student and understood what it truly felt like to succeed .
For much of my undergraduate experience and a short period during graduate school , I found myself isolated and @ @ @ @ @ @ @ unfamiliar to me , as my earlier educational experience consisted of constant collaboration .
When I began working with mentors from my community , who looked like me and were doing research that reflected who I was as a student , I realized how that increased my self-efficacy .
Collaborating with other Black students validated my existence in the field and made my experience more meaningful .
As a result , my own research focused on the intersection of identity and performing arts of Black physicists .
My collaborators and I collected and @ @ @ @ @ @ @ physicists , and found themes in the ways that their participation in the performing arts supported their experiences in the field as Black physicists ( ComPADRE PERC2018 Williams ) .
For so long , I was under the perception that I would be the only Black student I knew pursuing a degree in physics .
My research allowed me to find and connect with my community , which became crucial for my identity as a student .
Being a successful Black student in physics is about finding beauty in the most adverse experiences @ @ @ @ @ @ @ our success is rooted in our passion for physics , our family and the community that supports us .
We succeed regardless of how difficult or challenging the work may be .
The more I learn , the more I realize there is no guide or beginner ’ s manual on how to be a successful student ; the only real success is what you determine it to be .

This article is the second in a series of essays written by Black physicists and co-published with Physics Today as part of #BlackInPhysics week, an event dedicated to celebrating Black physicists and their contributions to the scientific community, and to revealing a more complete picture of what a physicist looks like.
Path to success: Physicist and artist Tamia Williams found that community and hard work were key factors to a successful start in physics. (Courtesy: Jordan Newell)
For a long time, I used to think success in physics mainly meant winning accolades, getting institutional recognition, and having an ingenious understanding of the subject. And to some degree, these factors do qualify for what it means to be a successful physics student. I was the first person in my family to pursue a degree in physics, and in time I realized that my measures of success as a student were completely different from what I expected. I found that being a successful student actually requires a strong foundational work ethic, persistent determination and communal support.
As the only daughter of two immigrant parents, and growing up in a typical Caribbean household, success was the only option. My grades were always expected to be 95% or above. The terms “I don’t know” and “I can’t” never existed in my vocabulary, and if I chose to embark on a new task, I was expected to finish it. My parents are the embodiment of hard work, dedication and a strong work ethic, as they left their native countries to have a better life for themselves in the US. Their resilience inspired me to be as hard-working, which was an essential factor in my success as a student. My parents knew my potential to attain the impossible, because they had done the impossible themselves.
When I decided to pursue physics as one of my majors at Mount Holyoke College, although my parents were unfamiliar with the subject, they were completely supportive of my decision. They became my emotional support in the mornings when I had to get up early to attend classes; provided a listening ear at night when I felt hopeless and lost about taking courses out of my league, such as electromagnetic theory or quantum mechanics; and were my biggest fans when I graduated from college magna cum laude. I was a successful student because of them – their unconditional support, love and work ethic led me to graduate with high honours in physics; write a senior thesis; and advocate for resources that were conducive to my well-being as a Black woman in physics.
Physics’ academic culture does not mirror the multifaceted identities of its Black students
If physics has taught me anything, it’s determination. I learned from early on that it is not an easy subject. For many Black students, when we first begin studying physics, we are often reminded that we are seeing and learning this material for the first time. We recognize and know that the culture, vernacular and coursework of physics disregard the vocabulary and syntax used throughout the Black community. Physics’ academic culture does not mirror the multifaceted identities of its Black students – rather, it exists in a world where Black students often do not have access to learning or becoming familiar with the material at a young age. Therefore, it usually takes us twice as long and requires twice the effort to complete assignments or gain a basic understanding of the subject.
When I find myself in these situations, struggling to keep up, I remind myself of the reasons I fell in love with physics: attending the free science museum days and learning about the solar system, or riding the subway system in New York and wondering how the trains worked. The curiosity I held as a child influenced my success as a student. While I never noticed that I was often the only Black girl running around the science exhibits, I remember how tenacious I felt doing physics and how determined I was to find the answers to every scientific question that I asked. As a student, I made sure to hold on to those same skill sets that I had developed as a child, which included having a natural inclination to wonder about the world and a genuine interest in scientific investigation.
However, the real secret to my success as a student is my community. That includes friends and other Black physicists who I have collaborated with and learned from along the way. Their support allowed me to see how I was impacting my community in real time. Towards the end of my undergraduate experience was the first time I felt I had finally found my place as a physics student and understood what it truly felt like to succeed. For much of my undergraduate experience and a short period during graduate school, I found myself isolated and doing physics alone. This situation was unfamiliar to me, as my earlier educational experience consisted of constant collaboration. When I began working with mentors from my community, who looked like me and were doing research that reflected who I was as a student, I realized how that increased my self-efficacy.
Collaborating with other Black students validated my existence in the field and made my experience more meaningful. As a result, my own research focused on the intersection of identity and performing arts of Black physicists. My collaborators and I collected and analysed the physics experiences of 13 Black physicists, and found themes in the ways that their participation in the performing arts supported their experiences in the field as Black physicists (ComPADRE PERC2018 Williams). For so long, I was under the perception that I would be the only Black student I knew pursuing a degree in physics. My research allowed me to find and connect with my community, which became crucial for my identity as a student.
Being a successful Black student in physics is about finding beauty in the most adverse experiences one can encounter. In academia, our success is rooted in our passion for physics, our family and the community that supports us. We succeed regardless of how difficult or challenging the work may be. The more I learn, the more I realize there is no guide or beginner’s manual on how to be a successful student; the only real success is what you determine it to be.