Comedian Ken Dodd helping to raise money for the appeal

It is the third "linear accelerator," which provides high-energy radiation treatment for patients at the unit's cancer centre.

The equipment was supported by a �900,000 donation from the Ron Smith Cancer Appeal.

More than 6,000 people have benefited from the centre's two other machines.

Margaret Smith started the appeal in memory of her husband, who died of cancer in 1990 and it has so far raised �2.5m.

"It was my husband's idea from the beginning that we had to have a cancer centre for north Wales and with the help of so many people that came about," said Mrs Smith.

"This has all been made possible from the rank and file of people in north Wales."

Comedian Ken Dodd is among people who have supported fund-raising events, the last time in March.

"I've known Ken for quite a number of years now and he's happy to help and although he has a very busy schedule, every few years he does something for us - and it raised a lot of money."

The hospital says the third machine will enable more patients to be treated

Conwy MP Betty Williams, who helped Mrs Smith start the charity, was at a ceremony to mark the installation of the machine at the North Wales Cancer Treatment Centre.

Most of the patients treated would have had to travel to the North of England for their treatments before the centre's opening at Glan Clwyd four years ago.

The third machine will enable an uninterrupted service, when the other two machines face maintenance.

Radiotherapy manager Nest Bowl said: "The provision of a local service has made life easier for patients, and the third linear accelerator means that many more patients can be treated."

The appeal's next target is to raise �700,000 for a new scanner for the hospital.