New technology allows more intense radiation to attack cancerous tumours without damaging surrounding tissue.
The system targets tumours
The technique, trialled at the Christie Hospital, Manchester, combines scanning with radiotherapy, giving a 3-D picture of the tumour during treatment.
Doctors can target tumours directly and safely increase radiation doses.
A £1m centre launched in Sussex on Monday will push forward development of the Synergy linear accelerator.
The system is said to be the first of its kind to provide real-time pictures while radiotherapy treatment is being given.
This allows better targetting of cancer cells, changes to intensity of radiation during treatment and the ability to complete the procedure more quickly.
The current process usually involves taking a scan prior to the treatment to identify the exact location of the tumour.
After surgery, radiotherapy is the best treatment method for cancer and accounts for 40% of all patients who are cured of the disease.
Ionizing radiation - similar to x-rays - can penetrate tissue and alter the part of the cell which regulates its growth and reproduction.
Healthy cells can recover from this damage, while cancer cells cannot.
Professor Chris Moore, consultant physicist at the Christie Hospital, said: "For the first time the system lets us see what we want to hit with our treatment by
giving us a continuous set of detailed three-dimensional X-ray images of the patient when they are lying down on the treatment couch.
"This means we can even move towards better cure rates by safely increasing the doses we deliver in radiotherapy."
More cancer centres in the UK are expected to be using the system later in the year.
It has been developed by researchers in Canada, the US and the Netherlands and the centre in Sussex is intended to further develop the equipment for worldwide use.
Out of date
The Royal College of Radiologists has complained that radiotherapy equipment in the UK is out of date. It found that a third of machines were at least 10 years old.
Professor Ann Barrett, dean of the faculty of oncology at the college, said: "The advantage of having an online imaging system is that it can instantaneously correct for any movement and ensure you are still treating what you intend to treat."
However, she said further evaluation of the system was needed to make sure additional radiation doses were suitable for patients.
There have already been advances in recent years to make the targettting of radiation beams more accurate, including the use of ultrasound, she said.