Ministers said the number of radiographers had increased

A parliamentary answer from Health Minister Malcolm Chisholm showed that the number of unfilled positions had risen from 26.7 in 2000 to 137 this year.

The Scottish National Party has claimed that the shortage could delay vital cancer care.

But Mr Chisholm said there had actually been an increase in the total number of radiographers.

The figures include therapy radiographers, who work with cancer patients, and diagnostic radiographers.

It is essential that we have enough qualified radiographers to deal with the number of patients who are suffering from the disease Christine Grahame Scottish National Party MSP

Greater Glasgow saw the greatest rise in unfilled posts, increasing from five in 2000 to 65.7 this year.

SNP MSP Christine Grahame described the figures as an "outrage".

"Cancer is one of our biggest killers in Scotland, so it is essential that we have enough qualified radiographers to deal with the number of patients who are suffering from the disease," she said.

"Although we must work towards reducing the number of people getting cancer in the first place, it is of little use to those who are suffering from the disease now if there is a massive shortage of qualified radiologists to treat them."

She said the Scottish Executive's drive to cut cancer deaths would fail unless the posts were filled.

I do not believe that patients are suffering because of a shortage of radiographers here in Glasgow Professor Alan Rodger Beatson Oncology Centre

However, Mr Chisholm said the figure was "meaningless" on its own.

"The health service generally has been expanded, so we have about 300 or 400 extra radiographers since 1999," he said.

"But the recruitment has not quite kept up with that and that is why there has been an increase in vacancies."

The Beatson Oncology Centre in Glasgow has recruited 10 radiographers since June - but still has 17 vacancies.

Medical director Professor Alan Rodger said: "I do not believe that patients are suffering because of a shortage of radiographers here in Glasgow.