Talking cancer-beating proton beams with Professor Carsten Welsch

There is more to accelerator physics than just smashing sub atomic particles against each other and putting together the puzzle of the universe. Here, Professor Carsten Welsch, Associate Director of the Cockcroft Institute tells cancer beating proton beams…

You’re Associate Director of the Cockcroft Institute. Give us a quick introduction to the Institute?

Accelerator physics is not just an exciting area of research it’s also an emerging industry.  The Cockcroft Institute is an international centre of excellence for accelerator science and technology in the UK, located at Daresbury Laboratory’s Sci-Tech campus. It is a unique joint venture between the Universities of Lancaster, Liverpool and Manchester and the Science and Technology Facilities Council (STFC). The institute carries out R&D into all aspects of particle accelerators and trains the next generation of researchers in this important field. New to the institute is the first CERN Business Incubation Centre which was signed in July 2012. This is a partnership designed to support and grow start-ups and small businesses based on technologies originating from high energy and accelerator physics. It will help businesses to grow from technical concept to market reality, accelerating start-ups into thriving high-tech companies.

How can proton beam therapy be used to treat cancer?

 The Clatterbridge Cancer Centre NHS Foundation Trust, is one of only a dozen centres in the world to offer ocular Proton Beam Therapy. We are working with Dr Andrzej Kacperek Head of Cyclotron to optimise control of the beam, with the aim to significantly shorten treatment time. Protons are heavy charged particles that penetrate tissue for a short precise distance and deposit most of their energy at the end of the beam. So, the target cancer is destroyed but the healthy tissue is spared. Unlike most types of radiation used in medicine, such as X-rays or electrons, proton beams can be directed to target just the cancer tumour minimising damage to healthy tissue and leaving almost zero dose beyond the tumour. This remarkable phenomenon is called the ‘Bragg Peak’. Although the peak itself is too narrow for use in radiotherapy, it can be spread using a modulator. The range and amount of modulation are tailored according to the shape and position of the tumour. This degree of precision is unique to ion beams. It is possible to control how deep the beam goes so it can be used to treat a tumour on the iris or one at the back of the eye. Also as protons scatter very little the beam has sharp edges, which makes it possible to follow the outline of the tumour and protect the optic nerve. However the techniques used for controlling the beam rely on the skill of the operator and sometimes rather basic instrumentation. For example, Dr Kacperek, has developed a ‘Bragg Peak Wheel’ (made from Perspex), to help measure the modulation and proton range required. A brass collimator is made at the workshop for each patient that tailors the cross-section of the beam to the exact shape of the tumour. We are working with Dr Kacperek to automate the calibration and reduce the set-up time per patient, which will increase the efficiency of this treatment.

Why isn’t proton beam therapy more common in cancer treatment?

There are two main limitations: size and cost. The necessary accelerator infrastructure requires a considerable fraction of a building for itself. There are about 30 proton therapy centres worldwide and these are capitally intensive projects. For example, in the UK the NHS is investing £250 million in two new high-energy proton beam therapy units at Christie NHS Foundation Trust in Manchester, University College London Hospital and University Hospitals Birmingham NHS Foundation Trust. Our research aims at improving the beam quality in these facilities and we hope that our work will result in instrumentation that can be used worldwide.

 What are the aims of the DITANET project at the institute?

Accelerator physics is not yet a ‘classic’ area of physics and the techniques for controlling the power of the beam are still very often in their infancy. The DITANET Project (DIagnostic Techniques for particle Accelerators - a European NETwork) aims to address this gap and fast track development of vital tools by creating a community of researchers across industry and academia. It was the largest EU funded project aimed at early stage and experienced researchers in beam instrumentation for accelerators and was coordinated by the University of Liverpool from the Cockcroft Institute. Its innovative research and training concept was found to be highly successful and we proposed two additional networks, oPAC (Optimisation of Accelerators) and LA³NET (Laser Applications for Accelerators), that were selected for funding by the EU and are based on DITANET’s training vision. Before coming to the Cockcroft Institute, I had previously worked in Japan, the USA, Germany and Switzerland and saw clearly the need for greater collaboration, in particular with industry. So in the early stages of DITANET we got business, universities and research centres involved to define their individual requirements and provide placements for our researchers and this has worked well.

What kind of tools are under development for optimising beam control?

We aim to develop techniques to measure properties of particle beams of all types, including electron beams and ion beams, both at low energy and extremely high energy, as well as instrumentation for the most advanced light sources on earth. This includes characterising the beam in terms of its longitudinal and transverse profile, intensity or energy. In particular we want to develop tools for non-destructive measurement so that is possible to measure in real time what is happening within the beam without disturbing it. For proton beam therapy, we are looking at the beam halo, which is created by natural scattering of protons when the beam passes through the air to reach the patient’s eye.  This creates a non-invasive way to provide quality assurance. The mechanical design for this detector has been finalised and first tests with the beam will be done over the next few months.Another example is the development of meters for next-generation light sources. It is now possible to generate time pulses of photon beams of less than a femtosecond (one millionth of a billionth of a second) in duration. This promises to enable very powerful camera systems capable of capturing chemical and biological reactions. At the moment we can generate these time pulses but not measure them, so we are working on diagnostics that can time resolve in femtosecond and tell us more about how life itself functions.