A woman with heart disease is angry that a scan she is due to have to help doctors diagnose her condition has been cancelled because of faulty equipment.

Sheila Cummings, 68, of Blenheim Way, Horspath, Oxford, has been told it will take six weeks before replacement apparatus is installed at the John Radcliffe Hospital, Headington, so she can have a myocardial perfusion scan.

The Oxford Radcliffe Hospitals NHS Trust, which oversees the JR, admitted that about 15 patients would be affected by the broken gamma camera, which is being replaced by state-of-the-art technology costing £280,000.

Retired hairdresser Mrs Cummings has suspected unstable angina, which causes constriction in the chest due to a narrowing of the arteries.

She has already been admitted to the JR casualty department five times with breathlessness and chest pains, and in November doctors said she needed a myocardial perfusion scan, to help them finally diagnose her condition.

During the technique, used in the department of nuclear cardiology, radioactive material is injected into a patient and generates pictures of the heart muscle through the special camera, allowing doctors to visualise blood flow to the organ.

Grandmother-of-five Mrs Cummings said: "I'm so angry. I had an appointment to go this week, and then on the day they phoned at 8.15am to say it had been cancelled because the camera was broken.

"I was just beside myself. It was jolly late to be telling people that their appointments were cancelled. I can't believe they don't have a second machine. It's unbelievable for a hospital the size of the JR."

An ORH spokesman admitted some patients would have to wait longer for their scans while a replacement camera was installed, but said they did not need to worry about their heart problems. She said: "We'd like to reassure patients that they will continue to have their symptoms treated as normal, and should their condition change or become urgent alternative procedures are available."

"We are unable to discuss individual cases publicly, but we are sorry to hear that Ms Cummings has concerns and would ask her to contact us directly so we can discuss these with her."