Some cancer patients want to know why Ontario's health plan doesn't routinely cover a high-techscanthat's apparently better at detecting certain cancers and is widely used in other provinces and countries.

The positron emission tomography or PET scan is accessible to patients in a number of provinces, including Quebec, British Columbia and Manitoba.

But in Ontario, Canada's most populous province, the $2,800 scan is only available in clinical trials.

"I'm a big fan of PET scans," says Howard Steinberg, a 41-year-old colon cancer survivor who says a PET scan saved him from unnecessary treatment.

A computed tomography or CT scan, which uses a series of X-rays, falsely determined his cancer had returned in his liver, he said.

He was preparing to endure lengthy, aggressive treatment when he decided to seek out a PET scan at a private health clinic in Mississauga.

"[The scan] informed me that there was no cancer spread to anywhere in my body," he said.

For a PET scan, a low-dose radioactive sugar is injected into the patient. Cancerous tissue absorbs more of the sugar, which is picked up by the scanner and appears brighter in the images.

The scan is said to detect changes in the biochemical processes in the body that suggest disease beforethey become noticeable in other tests like CT scans.

Clinical trials have beenunderway since 2002 in Ontario,and last year, more than 1,200 patients were tested using one of the province's nine PET imaging machines.

But Ontario is not yet convinced of the machine's merit.

"PET scan is a promising health technology. However, there is a dearth of high-quality evidence to show that it improves patient outcome," said Ministry of Health and Long Term Care spokesman A.G. Klei.

The province must follow procedure, he said, adding that future use of the machines depends on the results of field evaluations.

In the meantime, if a physician determines a patient could benefit from a PET scan, the option is there, he said.

He couldn't, however, provide an estimate of how long the waiting time might be.

A number of patients have decided to pay out of their own pocket at private health clinics where they can receive an appointment for a scan within a week of calling.

"We're already living in a two-tier system. They just don't want us to know that," said David Olinoski, who offers the scans at a private health care clinic in Mississauga.