A painting thought to be worth about £1m is to be sold by a Birmingham hospital to pay for a new treatment.
The portrait of Dr John Ash was painted in 1788 by renowned artist Sir Joshua Reynolds.
It is being sold by the Queen Elizabeth Hospital Birmingham Charity to help pay for a Cyberknife.
The Cyberknife is a type of radiotherapy which uses robots to target radiation at maximum dose to hard-to-reach cancer tumours.
The £3m device is so accurate that it even takes account of the patient's breathing movements.
The charity's chief executive, Mike Hammond, said the sale of the painting would allow them to buy the machine in December - a year earlier than anticipated.
Birmingham Museum and Art Gallery is trying to purchase the portrait for £900,000 which it said was of fundamental importance to the city.
It has raised £150,000 with donations from the Art Fund, but is pinning its hopes on the Heritage Lottery Fund which is due to make a decision on 7 June.
'Painted for Birmingham'
The painting, which has been on loan to the gallery since 1994, is also used in the school curriculum as a teaching aid.
Chris Rice, the head of heritage services at the museum said: "For the people of Birmingham, we have to get this.
"It was painted for Birmingham. It has always been in Birmingham. Its links to Birmingham's history are fundamental to the city."
Dr John Ashton founded Birmingham's first hospital, the General Hospital. The painting shows the hospital and its plans, and originally hung in the boardroom.
It is a huge full-length portrait and is noted to be one of the first major paintings of a bourgeois gentleman rather than an aristocrat.
When the General Hospital closed, its assets passed to the Queen Elizabeth Hospital, Birmingham.
One of the highest prices ever paid in Britain for a painting was £10.3m for Reynolds's Portrait of Omai in 2001.