Tag archives: medical physics
Proton therapy is an increasingly popular treatment technique that uses beams of protons to accurately target and destroy cancerous tumours. A new Physics World Discovery ebook, Proton Beam Therapy, takes a close look at the physics of this cancer treatment, its benefits and the challenges associated with bringing this approach into the clinical mainstream.
The ebook is written by Harald Paganetti, director of physics research at Massachusetts General Hospital and professor of radiation oncology at Harvard Medical School. He is a pioneer in advanced Monte Carlo dose calculations for proton therapy, and is considered the world expert on the relative biological effectiveness of proton beams.
In the last few decades, proton therapy has transitioned from research laboratories into the clinical setting – making this publication particularly timely. There are currently around 60 proton therapy facilities worldwide, and this number is increasing rapidly. “Proton therapy is becoming a standard treatment option but there are still many challenges in terms of the physics, biology and clinical use of protons, which are summarized in this ebook,” Paganetti explains.
By Hamish Johnston and Tushna Commissariat
You may not know it, but apparently you have a dedicated region in your brain that is your “physics engine”. At least that is what cognitive researchers from Johns Hopkins University are suggesting after they have pinpointed a specific region of the human brain that intuitively understands physics – at least when it comes to predicting how objects behave in the real world. According to the team, the engine is kick-started when we observe physical events as they happen and is “among the most important aspects of cognition for survival”. Surprisingly, the region is not located in the brain’s vision centre, but is actually the same area we tap into while making plans of any type. In the video above, the team has created a little game for you to test your engine’s horsepower – go ahead and tell us how you did.
By Hamish Johnston
I recently had the pleasure of visiting Matt Zepf, who directs the Centre for Plasma Physics at Queen’s University Belfast. Zepf and his colleague Gagik Nersisyan showed me around the TARANIS laser facility, which creates extremely bright flashes of light just like its namesake the Celtic god of thunder.
TARANIS is about to upgraded to TARANIS-X, which will deliver ultrashort pulses of extreme ultraviolet light (EUV) that are just a few attoseconds (10–18 s) in duration. Each attosecond pulse will deliver more than 10 µJ, which Zepf says will make TARANIS-X the most powerful laser of its kind by a comfortable margin.
By Margaret Harris
Imagine you’re a veterinarian and a trainer asks you to take a look at a horse. The animal, a champion showjumper, is limping slightly but there is no obvious injury. Exploratory surgery would probably do more harm than good, and the alternative – magnetic resonance imaging (MRI) – isn’t risk-free either. You’d need to put the horse under a general anaesthetic, and you know horses don’t react well to that; in fact, around 0.5% suffer serious injuries while coming round afterwards. And that’s assuming you can even find a scanner big enough to fit a horse. What do you do?
This might sound like a fairly niche dilemma, but for Hallmarq Veterinary Imaging it has become the basis for a thriving business – a business, moreover, that has just won an IOP Innovation Award for the successful application of physics in a commercial product.
At the awards ceremony – which took place last night in the Palace of Westminster, London, just down the hall from the House of Commons chamber – I caught up with Hallmarq’s operations and technical director, Steve Roberts. After sketching out the scenario of the veterinarian and the injured horse, Roberts, a physicist, explained that Hallmarq’s MRI scanner fits around the horse’s leg. This means that equine patients can simply be led into it, sedated but conscious. Sophisticated error-correction and image-processing software helps the scanner compensate for the horse’s movement, and in 15 years of operation, Roberts estimates that veterinarians have used Hallmarq’s machines to scan more than 60,000 horses.
By Hamish Johnston at the CAP Congress in Edmonton
In 1957 Atomic Energy of Canada built “a reactor that can do everything” at Chalk River, Ontario. Dubbed the National Reactor Universal – or NRU – that facility will shut down for good in 2018 and Canada’s neutron-science community is now pondering its future.
In the short term, physicists will have to travel abroad to use neutron sources, such as those at Oak Ridge in the US and Grenoble in France. The challenge during this 10–15 year period will be to keep the research community together and make sure that vital skills and expertise built up over decades at the NRU will be retained. In the longer term, there are calls for Canada to build a new neutron facility, but it is by no means clear whether that will happen.
By Hamish Johnston
Greetings from Edmonton on the western edge of the Canadian prairies, where I am starting my “Physics across Canada” tour. The nation’s physicists are gathering here for the annual Canadian Association of Physicists Congress at the University of Alberta.
The congress opens today with a session that promises to be out of this world. Exoplanet expert Sara Seager of the Massachusetts Institute of Technology is talking about the search for habitable worlds beyond our blue planet. I am really keen to learn more about the latest techniques for studying the atmospheres of exoplanets and I plan to record an interview about that very subject later this week.
By Tami Freeman
Medical imaging is a multidisciplinary science encompassing a wide range of powerful techniques with applications in both patient care and fundamental biological studies. In this latest Physics World focus issue, we examine how imaging technologies such as X-ray computed tomography (CT), magnetic resonance imaging and other nuclear, ultrasound and optical imaging techniques have evolved in recent years. We also take a look at what improvements can be expected in the future.
By Margaret Harris at the AAAS meeting in San Jose
“Restoration of sight to the blind” is a brave claim, one with an almost Biblical ring to it. For Daniel Palanker, though, it is beginning to look as if it is an achievable goal. A medical physicist at the University of Stanford, Palanker has developed a prosthetic vision system that replaces damaged photoreceptors in the retina with an array of tiny photodiodes. When infrared images are projected onto this array, the photodiodes convert the light pulses into electrical signals, which are then picked up by the neurons behind the retina and transmitted to the brain. The result is an artificially induced visual response that, while not as good as normal vision, could nevertheless provide “highly functional restoration of sight” to people with conditions such as retinitis pigmentosa or age-related macular degeneration (AMD).
By James Dacey
The story of young brain-tumour patient Ashya King has gripped the British public over the past few weeks, with every twist and turn covered extensively in the media. In a nutshell, the five year old was removed from a hospital in Southampton at the end of August by his parents, without the authorization of doctors. They wanted their son to receive proton-beam therapy, which was not offered to them through the National Health Service (NHS). The family went to Spain in search of the treatment, triggering an international police hunt that subsequently saw the parents arrested before later being released.
The drama was accompanied by a heavy dose of armchair commentary, with Ashya’s parents, the hospital in Southampton and the police all receiving both criticism and praise. Even the British Prime Minister, David Cameron, got caught up in the affair, as he offered his personal support to the parents. To cut a long story short, Ashya’s parents finally got their wish and they have ended up at a proton-therapy centre in the Czech Republic where their son’s treatment begins today.
But what is proton therapy? It is a relatively new medical innovation that shows great promise in the treatment of cancer, though it is only currently available in certain countries. Beams of protons can be directed with precision at tumours in the body – allowing the energy to destroy cancer cells, while causing less damage to the surrounding tissue than is possible with conventional radiation therapies. The treatment, however, is only really useful in specific cases of cancer, such as where is vitally important that surrounding structures are not damaged. And because it is relatively new, there is less information available about how effective it is compared with more established treatments.
By Hamish Johnston
In the 25th anniversary issue of Physics World, I made the bold assertion that laser acceleration will bring particle therapy to the masses by removing the need for treatment centres to have large and expensive accelerators. Instead, therapeutic beams of protons and other charged particles will be made using compact and relatively inexpensive lasers.
Now, medical physicist Umar Masood and colleagues at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and the University of Dresden have published plans for a laser-driven proton-therapy facility.