Dr Hans Raetz, of the Queenstown Medical Centre, said he expected the Wakatipu Heath Reference Panel, now being formed, would make the case for a scanner in the resort's hospital.
The case would back up the National Health Board (NHB) panel's recommendation to the Southern District Health Board (DHB) early last month.
"The argument that Dunstan Hospital is bringing forward is that Dunstan has 250 referrals a year for CT scanning and Queenstown has only got 170," Dr Raetz said.
"Of the 250, you'd probably have to take at least 100 out because they are acute referrals from the Wanaka ski fields.
"If you have got a trauma centre in Queenstown and you truly have only one health board, which is still not happening, then clearly from Cardrona you wouldn't send somebody to Dunstan, you would send them to Queenstown.
"Even travel time and flying time is equidistant, so if you take these 100 referrals out of the Dunstan argument, you're left with a 150. Queenstown has already got 170 plus the 100 who would definitely come to Queenstown anyway, then you've got 270 to 150."
Dr Raetz said Queenstown was also the home of international ski teams and snow sports. A financially sustainable CT scanner would need private business and there was plenty of work being sent to CT scanners in Dunedin or Christchurch.
International ski team members may not need a scan, but they want a scan for peace of mind and will pay out of their own pocket, he said.
The Lakes District Hospital "was supposed to become the secondary, almost non-existent, site [but] is now becoming the main site.
"Dunstan will lose in this in more ways than one and I think Dunstan will remain doing exactly what it's doing now.
"The moment we get the CT scanner to Queenstown, this is going to be the new hospital for the Central-Queenstown area.
"If you get the public volume and a little bit of private volume you can make them stand up within a year or two and that thing will make a profit.
"I've seen the numbers and it does support it all the way through. It doesn't support two CT scanners in the region and that is the problem.
"The moment the DHB decides their volume will go to Queenstown, that's it for Dunstan."
Russell McGeorge, of Wanaka, the chairman of the company which runs Dunstan Hospital, said he would not comment on anything until he had seen it "and I suspect I wouldn't comment anyway because we're not into making it competitive".
The DHB noted "further information" had been provided to the NHB panel regarding its CT scanner in Lakes District Hospital recommendation, during the board's latest monthly meeting, in Dunedin, early this month.
DHB planning and funding general manager Robert Mackway Jones said the further information contained the total number of scans performed at Southland Base Hospital and Dunedin Hospital for patients from the Lakes catchment and Dunstan catchment, broken down into broad categories of in-patient, out-patient and emergency.
"Of these scans only a portion are likely to be able to be undertaken locally," he said.
The panel was to provide its thoughts to the board for the November meeting. The requested financial analysis was provided by the NHB, although DHB management had yet to finalise a view on it.
