Two radiation oncology centres have been officially opened at Beaumont and St James's hospitals in Dublin.
The centres cost around €60m and became operational last year.
According to the National Cancer Control Programme, the centres will ultimately increase radiation oncology treatment capacity in the east of the country by 50%.
For some patients it will eliminate the need to travel abroad for services that are now available in Ireland for the first time.
The two centres offer RapidArc intensity modulated radiotherapy, allowing more precise delivery of the radiotherapy dose to the target area.
This is particularly useful where a high dose of radiation is needed to treat a tumour that is close to normal organs.
The system reduces treatment times by up to 80% for head and neck cancer.
Over 4,000 patients a year will be treated at the two centres and the cancer service at St Luke's in Rathgar.
Experts say that there will be a 100% growth in the number of cancers detected over the next ten years.
The new centres were opened by Minister for Health James Reilly.
Minister Reilly has said that the future of St Luke's Hospital as a cancer care centre is secure.
He said cancer care would continue at St Luke's for as long as he could see into the future.