Edinburgh-based Blackford Analysis won the backing from a group of investors that includes the Archangels and TRI Cap angel sydicates. The group provided the same amount in 2012.
Blackford Analysis has developed software that greatly reduces the amount of time it takes to read imaging data and says its software could help doctors cut the amount of time taken to compare multiple images by about 20 per cent.
The company expects its software to be included in imaging systems sold by companies in the USA, which should generate about £3 million to £4 million in revenue over four years.
"The last couple of years have been very exciting for Blackford Analysis and we are delighted to have secured this new investment to help us achieve our growth objectives," said founder and chief executive Dr Ben Panter.
The company will use the funding to develop products that will help it expand beyond its core radiology market in hospitals.
A spin-out from Edinburgh University, Blackford built the software from technology developed in the university's school of physics and astronomy to determine the age of stars. The technology was used to speed up the processing of the massive amounts of data collected by observatory telescopes.
Edinburgh University's Old College Capital and the state-funded Scottish Investment Bank supported the latest funding round and the one completed in 2012.
Blackford Analysis won seed funding from US-based angel investors in 2010.