A revolutionary machine that scans and kills cancer at the same time is to be tested on patients in the UK.
Experts say the MR-Linac machine to be installed at two centres in Surrey and Manchester could open up a new era in highly-personalised radiotherapy.
The machine combines magnetic resonance imaging (MRI) scanning and tumour-busting radiation treatment in one hi-tech package.
Two of only seven of the machines in the world are being delivered to the UK, initially for use in clinical trials.
Each device is understood to cost more than a £3 million CyberKnife - a cutting-edge form of radiotherapy that hits hard-to-reach tumours with high-dose targeted beams.
One of them will be commissioned at the Royal Marsden Hospital's site in Sutton, Surrey, early next year.
Professor Uwe Oelfke, from the Institute of Cancer Research and the Royal Marsden NHS Foundation Trust, said a major problem for radiotherapy was that patients' internal anatomy changed "from day to day or even from second to second".
Being able to view highly-detailed MRI images of a radiotherapy target site would allow far more accurate treatment with less damage to healthy tissue and fewer side effects.
"It's extremely important for the success of radiation therapies that we can see what we want to treat at the time of the treatment, not diagnostic images which are basically reflecting the anatomical state a few days or weeks before the treatment," said Prof Oelfke.
"With MRI you can constantly monitor the patient while the patient is being treated and adapt the dose precisely to the individual patient. This will allow a truly new practice of personalised radiation therapy."
The MR-Linac machine would also make real-time monitoring of a patient's response to treatment possible, marking a "step change", said Prof Oelfke.
An early trial at the Royal Marsden to demonstrate the machine's safety and effectiveness involving about two dozen patients is now in the planning stage.
Patients with tumours affecting different parts of the body will be recruited, including brain, head and neck, lung, oesophageal, pancreatic, breast, prostate, cervix and rectal cancers. They will be among the first in the world to use the machine.
Later studies will compare outcomes from patients given standard radiotherapy and those using the MR-Linac.
Professor Kevin Harrington, joint head of radiotherapy and imaging at the Institute of Cancer Research, London, said: "The UK will play a central role in the development of this new technology for the treatment of cancer."
A Government grant of £9.6 million funded the purchase and installation of the machine at a new facility at the Royal Marsden.
The award formed part of a £230 million investment package in UK science handed out by the Medical Research Council.