A backlog in analysing X-ray films has left patients at risk, hospital bosses have admitted.
The North West London Hospital NHS Trust acknowledged there was a possibility of patients' potentially life-threatening conditions being missed due to unreported X-ray films.
In a report released last week the trust said it was considering buying in extra radiologist time over the next five months to clear a backlog of 30,000 films.
The organisation, which runs Northwick Park Hospital, in Watford Road, and Central Middlesex Hospital, in Acton Lane, Wembley, performs 310,000 X-ray examinations each year.
A spokeswoman said: "The risk identified in our register relates to a backlog in the number of X-rays being 'formally reported' by radiologists.
"This does not mean that those X-rays were not reviewed or acted upon. All our X-rays are reviewed by the radiographer performing the test, and the doctor who requested it.
"This allows a diagnosis to be made and treatment of the patient's condition to be managed appropriately."
The formal reporting process involves a radiologist double-checking X-rays for any abnormalities unrelated to the patient's condition. Sometimes a condition no-one suspected will be picked up this way.
The trust said fewer than 0.2 per cent of X-rays normally require follow-up investigation, meaning up to 60 of the patients' films could have something serious on them that neither the doctor ordering the scan or the patient are aware of.
In order to tackle the problem the Trust has put film streaming systems in place to prioritise film types and who has viewed them.
Councillor Barry Macleod-Cullinane (Con), portfolio holder for adult services, said: "It is a concern that systems aren't working together the right way.
"We are hoping the concerns will be put right so that we do not have issues of misdiagnosis, but this is the point of having risk registers - so we can identify things that need to be resolved."