Health bosses have offered an explanation as to why a potentially life-saving £500,000 piece of kit has been sitting unused for a year.

The radiotherapy machine, which can be used during surgery to treat tumours, was bought for the breast cancer unit based at St Margaret’s Hospital in Epping a year ago.

Medics are frustrated that not a single patient has yet benefitted from the targeted radiotherapy it can provide, and blame the health authorities in charge of giving its use the go-ahead.

Trials of the treatment in the US have shown benefits to patients in terms of treating tumours and reducing the side-effects of conventional radiotherapy.

But Marc Davis, director of development at Princess Alexandra Hospital in Harlow, where the treatment would take place, said essential safety checks had to be done before the machine was used.

He added: “The hospital is in the process of trying to produce new technology which is very cutting-edge.

“The new piece of equipment carries health and safety issues.

“For example, the operating theatres need to be checked out by physicists to make sure they are suitable for the type of radiation associated with it.

“Staff have been trained and a whole raft of things has been put in place.”