A teenage cancer patient who was accidentally given 17 overdoses of radiation during treatment has died, almost a year after the mistake was discovered.

Lisa Norris, 16, was diagnosed with a brain tumour in October last year and was admitted to the Beatson Oncology Centre in Glasgow, Scotland's largest cancer hospital, which has administered more than 29,000 radiation treatments in the past 20 years.

After undergoing a series of 17 radiotherapy sessions at the hospital the schoolgirl was told in January that the tumour had disappeared. Within days, however, consultants from the hospital were forced to break the news that each time she underwent treatment she had been given 65 per cent more radiation than she should have been.

The doctors warned her, and her parents, Ken and Liz, that the overdose could prove fatal or at least leave her paralysed and suffering brain damage.

"We don't know what's in the future because I could be brain-damaged, I could be paralysed," said Lisa shortly after being informed of the errors.

"Later in the future, in 10 to 15 years, I could not be here. It's just time that will tell if anything is going to happen."

Lisa, from Girvan in Ayrshire, who underwent extensive oxygen treatment to try to combat the mistake, suffered discomfort from the radiation as her body turned red, broke out in weeping sores and affected her internal organs.

Her cancer returned in the summer and in September Lisa was taken to Glasgow's Southern General Hospital for a two-hour operation to remove fluid from her brain. Although she was reportedly back on her feet within a week, the cancer spread to her spine and started to take hold in other parts of her body. She died at home on Wednesday, surrounded by her family.

A post-mortem examination will be performed to determine whether the cancer or the radiation overdose was ultimately responsible for her death.

Her parents are certain, however, that the radiation overdose, which the hospital said was caused by human error, was to blame. "We remain convinced it was the overdoses that did this, not the cancer," Ken Norris told the Daily Record. "We knew things weren't looking good but we never ever expected Lisa to pass away so soon. We had hoped to see Christmas".

An investigation into the overdose at the Beatson centre, which is run by NHS Greater Glasgow and Clyde, has been launched by the Scottish Executive and a spokeswoman said yesterday that although the findings were in the "final stages of preparation" she was unable to indicate when they would be issued. Since the discovery of errors in Lisa's case health officials have disclosed 46 incidents where the planned treatment of patients was different from what had actually taken place over the past 20 years - including 14 cases where patients were given overdoses.

Sir John Arbuthnott, the chairman of NHS Greater Glasgow and Clyde, said staff were "extremely upset" to hear of Lisa's death.

Her funeral is expected to take place next week.