High Resolution Fast Detector for Quality Assurance in Proton Beam Therapy

Lead Research Organisation: University College London
Department Name: Physics and Astronomy

Abstract

Modern cancer treatment is largely a combination of 3 techniques: surgery, chemotherapy and radiotherapy. Radiotherapy uses beams of X-rays to irradiate the tumour from many different directions. The effect is to kill the cancer by depositing as much radiation dose in the tumour as possible.

Proton therapy is a more precise form of radiotherapy that provides significant benefits over conventional X-ray radiotherapy. Protons lose energy - and therefore deposit their dose - in a much smaller region within the body, making the treatment much more precise: this leads to a more effective cancer treatment with a smaller chance of the cancer recurring. This is particularly important in the treatment of deep-lying tumours in the head, neck and central nervous system, particularly for children whose bodies are still developing and are particularly vulnerable to long-term radiation damage.

In 2011 the UK government announced funding for 2 full-sized proton therapy centres, to be based at University College Hospital in London and The Christie in Manchester. These will provide treatment for a much wider range of cancers, allowing more patients to be treated closer to home. Procurement for these centres began in 2013, with doors expected to open some time after 2018. Unlike the majority of proton therapy centres worldwide - particularly in the US - the 2 UK centres are publicly funded and will treat some of the most challenging cancers.

Treating these cancers requires machinery that is significantly more complex than a conventional radiotherapy system. Protons are accelerated to the right energy for treatment by a particle accelerator: once the beam leaves the accelerator, it then has to be transported to the treatment rooms many metres away by a series of steering and focussing magnets. When the proton beam reaches the treatment room, it has to be delivered through a gantry to the correct place. Proton therapy gantries are enormous - more than 3 storeys tall and weighing more than a hundred tonnes - and have to rotate around the patient to deliver the beam from any angle with millimetre precision.

In order to ensure that treatment with such complex machinery is carried out safely, a range of quality assurance (QA) procedures are carried out each day before treatment starts. The majority of this time is spent verifying that the proton beam travels the correct depth and is carried out for several different energies: protons are counted at different depths in a plastic block that resembles human tissue. These energy QA measurements take significant time to set up and adjust for different energies: the full procedure normally takes an hour.

This project is looking to develop a detector that will make more accurate and more rapid measurements of the proton energy than existing systems. A calorimeter - used to measure a particle's energy - that was developed for the SuperNEMO high energy physics experiment has been modified to record the energy of a proton therapy treatment beam. This system can measure proton beam energies much more quickly than the existing energy QA technology primarily because it is much simpler. Protons are absorbed by a plastic scintillator that converts the particle energy into light: this light can then be detected to measure the particle energy. By making the scintillator the right size and shape, proton beams over the full range of treatment energies can be measured without having to change anything about the detector system. This would allow the complete morning energy QA procedure to be carried out in a few minutes. At the two UK centres, this would translate into being able to treat an extra 12 patients every single day.

In addition, because so much light is produced by protons stopping in the scintillator, the proton energy can be measured to better than 1%. This means that the accuracy of the energy measurement will also be better than the existing technology.

Publications

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Kelleter L (2020) A scintillator-based range telescope for particle therapy. in Physics in medicine and biology

 
Description A detector was successfully built and commissioned at medical proton therapy facilities. We demonstrated the feasibility of measuring the proton beam energy with a <1% precision, which is a legal QA requirement for PBT centres. The device is much more compact, cheaper and makes QA measurements in a fraction of the time compared to current commercial analogues.
Exploitation Route Based on the outcome of this research a new proposal for a range calorimeter was made and funded. The range calorimeter has been built and successfully commissioned. Its mass production and deployment at PBT centres around the world is currently being studied from scientific, technical and marketing perspectives.
Sectors Healthcare

URL https://physicsworld.com/a/mixed-ion-beams-could-enhance-particle-therapy-accuracy/
 
Description The proposal was part of an iterative process to build a QA device that could be licensed at medical centres providing cancer therapy with proton beams. The outcomes of this proposal led to the design and successful commissioning of a range calorimeter that is capable of measuring water equivalent path length of clinical proton beams with a sub-mm precision. It also led to a recently funded marketing studies of the device.
First Year Of Impact 2018
Sector Healthcare
Impact Types Societal

 
Description IPS
Amount £148,000 (GBP)
Funding ID ST/P003664/1 
Organisation Science and Technologies Facilities Council (STFC) 
Sector Public
Country United Kingdom
Start 04/2017 
End 03/2018
 
Title Clatterbridge Data 
Description A simple set of digital and ascii data stored at UCL server with daily backups. 
Type Of Material Data analysis technique 
Provided To Others? No  
Impact Too early to say. But data analysis technique of the "on-the-fly" pulse shape processing may find its way in proton therapy and other applications. 
 
Description Clatterbridge 
Organisation Medical Oncology, Clatterbridge Centre for Oncology, Merseyside, United Kingdom
Country United Kingdom 
Sector Private 
PI Contribution Investigated beam performance at Clatterbridge. Confirmed <1% energy spread of clinical proton beam. Discovered non-uniform timing structure of Clatterbridge beam. Characterized spatial uniformity of Clatterbridge beam. Offered conceptual design of QA setup.
Collaborator Contribution Provided clinical test beam facility for developing QA detector Provided technical and logistical support during test beam runs Offered accelerator physics and engineering expertise to optimize beam conditions Clinical expertise input into detector design.
Impact The research project under this award is still ongoing. It is therefore too early to talk about the outcomes. We certainly expect significant outcomes at the end of the project that will lead to a development of instrumentation for proton cancer therapy treatment. It is a multidisciplinary collaboration that involves particle physics, medical physics, accelerator physics, radiotherapy.
Start Year 2016
 
Description Hamamatsu 
Organisation PMT Hamamatsu Photonics K.K.
Country Japan 
Sector Private 
PI Contribution We carried out a comprehensive characterisation of 8" PMTs and provided the feedback which resulted in significant improvement of the performance of these PMTs
Collaborator Contribution Hamamatsu produced an 8" PMT with unprecedented energy and time resolution characteristics
Impact A new type of an 8" PMT has been developed which offers superior energy and time resolution characteristics. With improved performance it will now find its use in many other cutting edge physics experiments: especially in neutrino physics and applications where a good resolution or a low light level detection is necessary.
Start Year 2006
 
Description NUVIA 
Organisation NUVIA a.s.
Country Czech Republic 
Sector Private 
PI Contribution Building and testing optical modules. Carry our measurements at clinical beam lines. Analyse test beam results. Interpret results in terms of Quality Assurance at PBT facilities.
Collaborator Contribution Development of chemical composition and manufacturing process for advanced plastic scintillators. Production and supply scintillators for optical modules.
Impact Development of an apparatus for measuring the energy of protons at clinical PBT facilities with a record resolution of 1% for 60 MeV protons at the Clatterbridge facility, for rates up to 50 kHz. The collaboration is multidisciplinary bringing together technologies developed as part of a core particle physics research programme (the SuperNEMO experiment), medical accelerators and clinical cancer research and treatment technologies.
Start Year 2016
 
Description MedAustron seminar 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A seminar at the MedAustron proton therapy centre in Austria. A talk was given (followed by a discussion) on results obtained at Clatterbridge.
Year(s) Of Engagement Activity 2017
 
Description UCL Science Society 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact A talk and a debate on using physics technologies in medicine took place under auspices of UCL Science Society. It generated a lot if interest and led to invitations to further seminars as well as to undergraduate students volunteering to do research with our group.
Year(s) Of Engagement Activity 2015