AN expert group will have less than two months to report back to the Government on alternatives for the long-awaited national children's hospital.
Health Minister Dr James Reilly said the team must examine why planners rejected the Mater site and consider different options.
He maintained that the Government was still committed to the project and that all options were on the table, including building on a greenfield site.
"We are asking them to give us their best advice on what's the best way forward," said Dr Reilly.
"We are very cognisant of the fact that this is a hospital that will serve us for 100 years or more and while we want to build it as quickly as possible we don't want to rush it either."
An Bord Pleanala refused permission for the 650 million euro facility in the controversial north Dublin site, warning the 16-storey glass building was not sustainable and would overwhelm the Georgian district.
Coombe Hospital in south Dublin and a group of farmers in south Dublin have since offered separate sites for the facility.
Businessman and former Health Service Executive chairman Dr Frank Dolphin will spearhead the review team, with members who have architectural and clinical expertise to be appointed next week.
They will have 56 days to make recommendations on how plans for the 400-bed Children's Hospital of Ireland can progress with minimal delay.
The terms of reference include examining government policy on the delivery of health services, the cost and value-for-money considerations of the different options, the likely timelines associated with the different options and the implementation risks associated with the different options.
Dr Reilly admitted it would be challenging for the new hospital to be built on a greenfield site within the lifetime of the Government but said advantages include better access and being able to build 24 hours a day.
However, he said he believes co-location with an adult hospital site or tri-location with a maternity hospital was important.
"I've made it very clear from the outset that my most important objective is to build the hospital as quickly as possible," he added.
"There's advantages and disadvantages (to each option) and I think this expert group will take a long hard look at that.
"I don't think it would be right for my to prejudge anything that will come out of it."
Alternative locations include downsizing the Mater site, co-location at Tallaght Hospital or Connolly Hospital in Blanchardstown, a new standalone paediatric centre at Newlands Cross or redeveloping Crumlin.
Meanwhile the Medical and Research Foundation at Crumlin children's hospital yesterday launched an appeal for 8 million euro to help renovate the hospital's cancer ward and build a cardiac facility.