“The Pravda project is a perfect example of how advances in the physical sciences can contribute to the search for solutions in healthcare. The technology holds much promise for improving treatment for cancer patients and we are pleased to support its development.”
Ted Bianco - Director of Technology Transfer at the Wellcome Trust
Dr Grainne Riley
PRaVDA Project Managerc/o Nigel AllinsonEMTECUniversity of LincolnBrayford PoolLincoln LN6 7TS
Professor Nigel M Allinson, MBE
Project Director and Principal Investigator
Distinguished Chair of Image EngineeringLincoln School of Computer ScienceUniversity of LincolnBrayford PoolLincolnLN6 7TS, UKPhone: +44 (0) 1522 837 710Mobile: +44 771 470 3125
Radiotherapy is a fundamental weapon in the battle against cancer with some 40% of patients receiving it as part of their treatment. Proton therapy (PT) enables a lower integrated radiation dose to a patient receiving radiotherapy (compared to x-rays) due to the finite range of protons and so allows more accurate targeting of the dose. The underlying physics that permits this is the proton's Bragg peak, which increases the dose deposited at a tumour site, even if deep inside the body, as well as reducing the dose to neighbouring healthy tissue. However, PT is more sensitive to uncertainties in both treatment planning and delivery than conventional x-ray treatment .
To overcome these limitations of these uncertainities in planning and delivering PT, the Wellcome Trust is funding the PRaVDA Consortium to develop new concepts and instrumentation to provide accurate information about the proton beam’s dose, energy and profile before and during treatment.
PRaVDA is a team of leading instrumentation engineers and scientists, medical, high-energy and nuclear physicists and oncologists from the Universities of Birmingham, Lincoln, Liverpool and Surrey, the University Hospitals Birmingham NHS Foundation Trust and the University Hospitals Coventry and Warwickshire NHS Trust, the iThemba Laboratories (Cape Town, South Africa).
A few facts and figures.
- Each year over 320 thousand people are diagnosed with cancer in the UK
- More than 1 in 3 people in the UK will develop some form of cancer during their lifetime.
- The main cancer treatments are surgery, radiotherapy, chemotherapy; with 40% of patients receive radiotherapy as part of their treatment.
- Around 120,000 cancer patients in the UK, and millions worldwide, benefit from radiotherapy every year.
- Radiotherapy helps cure more people than cancer drugs and is generally the lowest cost treatment option.
- Wordwide there are over 40 operational proton therapy centres with many more planned.
- UK Department of Health confirmed in December 2011 that proton therapy will be made available for patients in the UK through two new treatment centres, in London and Manchester. Patients will be able to have treatment here from 2017.
PRaVDA will be the world’s first silicon-based detector system that will allow the in-situ monitoring of the incident dose, in terms of its fluence, energy and distribution both prior and during treatment; and provide quality images during treatment as well as realise interactive proton computerised tomography (CT) – the ultimate aspiration for radiotherapy.
This three-year adventurous project brings together the UK’s leading detector and instrumentation scientists together with medical physicists and oncologists in close partnership with industry and other stakeholders. PRaVDA has use of the UK’s only research proton facility for extensive testing, and guaranteed access to other cyclotrons at key PT treatment centres; together with unique skills in designing novel detectors that lie at the heart of PRaVDA.
How Radiotherapy works
Damaging the DNA within cancer cells will stop them growing or they may even die .– radiotherapy deposits high levels of energy in the cancerous cells to cause their DNA to become damaged. When the cells die the body breaks them down and gets rid of the waste chemicals. Normal cells in the radiotherapy region may also be damaged but they can usually repair themselves.
Most external radiotherapy uses high-energy x-ray or gamma beams (photons) with energies between a few 100 keV and tens of MeV. The energy deposited in tissue as an x-ray or gamma beam passes through falls off approximately exponentially from the surface. To ensure the maximum energy is deposited at the tumour site, the beam is rotated and shaped; so that over the entire treatment session the majority of the photon energy is deposited at the tumour site.
For general information on radiotherapy visit cancerhelp.cancerresearchuk.org/about-cancer/treatment/radiotherapy
Proton therapy uses beams of protons – these are the elementary particles in the atomic nucleus that carry a positive electrical charge. They release some energy as they slow down passing through the tissue. However, there is a peak of energy released towards the end of their journey and this can be manipulated to be at the target – the cancer. This peak is called the Bragg Peak as protons release most of their energy when they stop rather than when they are travelling through the tissue.
Proton therapy can increase the likelihood of killing cancer cells by giving a higher dose of radiation straight to the tumour, while reducing damage to healthy tissue between the charged particle radiation source and the tumour, and sets a finite range for tissue damage after the tumour has been reached. The dose curve below illustrates how dose and depth penetration may be manipulated, through modifying the proton's energy, so that the maximum dose at the Bragg Peak is localised at the tumour site.
The capabilities of proton therapy over conventional photon therapy are illustrated through the dose density distribution models for a nasopharyngeal (throat) tumour. The coloured regions show that some radiation dose is deposited other a large volume of the brain in the case of photons (x-rays), but much less for the better targeted protons.
Proton therapy is particularly beneficial for tumour sites near other critical structures or organs – for example, ocular tumors (uveal melanoma), skull base and paraspinal tumours (chondrosarcoma and chordoma). The other area of treatment is cancer occurring in young children, where the increased dose to surrounding healthy tissue can result in an additional long-term cancer risk.
Proton Therapy in the UK
People who have melanoma of the eye can have proton therapy at the NHS Clatterbridge Centre for Oncology, Wirral, Merseyside
Currently the NHS will pay for people to go abroad if it is considered that they will benefit from proton treatment for cancers in other parts of the body.
In December 2011, the UK Department of Health confirmed that proton therapy will be made available for patients in the UK. There will be two new treatment centres, in London and Manchester. Patients should be able to have treatment at these centres from 2017.