A hospital trust has been fined £45,000 after it lost a radioactive substance and took nearly three months to notice.
The missing rod was never found
The Royal Free Hospital in Hampstead, north-west London, mislaid a caesium 137 rod after it was used to treat a cancer patient in March 2001.
On Friday, the hospital trust pleaded guilty to seven offences under the Radioactive Substances Act and health and safety at work legislation.
It was ordered to pay the fine and £45,619 legal costs.
The rod, which was never found, was the size of a pen tip and used to burn away malignant cancer cells.
It was thought to have been returned to a locked store, but instead it was thrown out with the clinical waste.
A spokesman for the Royal Free Hampstead NHS Trust said it had since reviewed its procedures for handling such substances.
He added: "The source would have to be in close contact with a person's body for many hours to pose any risk."
The case, at City of London Magistrates' Court, was brought by the Health and Safety Executive and the Environment Agency.
They said there were "serious deficiencies" in the trust's handling and storage of the substance and weaknesses in staff training and procedures.
Environment Agency officer Adrian Bush said the case highlighted the trust's failure to protect its own staff.
He added: "Those entrusted with radioactive material have a great responsibility to manage and dispose of such potentially harmful substances appropriately."