Mr Thomson said neither the committee, nor the public, had a timeline for when the problem would be fixed, and how it would happen.
''These are procedures that across the ditch [in Australia] would happen overnight,'' he said.
He emphasised his comments were not to be taken as criticism of staff, who were working hard.
What was clear was that southern patients had to get used to travelling to other hospitals for scans, and that meant Dunedin people, as well as those in places such as Central Otago, he said.
A report to the meeting, in Dunedin, shows patients are waiting 40 weeks for a CT scan at Dunedin Hospital, and 35 weeks for routine MRI, and there is a large unscheduled waiting list for the procedures.
The board has been trying to address the problem for about the past two years, and last month launched a new ''programme for change'' to tackle it.
Patient services executive director Lexie O'Shea said the Dunedin Hospital radiology situation was not new, and there was no quick fix. The review would take 12 months, although she expected to see improvements sooner. As yet, the board still did not understand the problems preventing timely scans, and it was important to determine those first.
Earlier this week, Oamaru Hospital general manager Robert Gonzales told the Otago Daily Times the hospital's CT scanner was working at about 35% capacity, and could scan patients from outside Waitaki if the board required.
The hospital has just signed an agreement with the health board to scan more Oamaru area patients, from this month.
The health board's elective surgery discharges are 3% below its plan for the six months to the end of December, the committee heard.
