A woman who suffered a suspected heart attack was diagnosed with cancer after a doctor ordered extra scans.
The Reverend Rosie Bouch visited hospital last December after chest pains, and was cleared for signs of a heart attack.
However, her doctor ran more tests and found she had stage one lung cancer.
The technology used is now being mobilised to detect lung cancer in smokers before it develops, and could help beat cancer early.
Ms Bouch, 61, from Brislington, Bristol, is not a smoker and was at extremely low risk of developing lung cancer.
She only became aware she had cancer after additional tests were ordered by a doctor who, despite finding she was not at risk of a heart attack, was not convinced.
A spiritualist and ordained minister, Ms Bouch has praised the technology in helping her avoid the trials of cancer treatment.
Ms Bouch said: “Within six weeks of having that scan I was being operated on at the BRI.
“They told me all the way along the line how lucky I was because they had found it as early as they did.”
For people like Ms Bouch, or those who have ever smoked, the Somerset Wiltshire Avon and Gloucestershire Cancer Alliance (SWAG) have set up a mobile site for CT scans.
The unit will be carrying out the scans at community locations such as supermarkets and school car parks in Bristol, Bath, Bridgwater and central Gloucester.
The tests are aiming to pick up small lung tumours before symptoms begin, as lung cancers detected early are more treatable and have a better life expectancy.
Around 27,000 individuals across the West aged 55 to 74 will be invited to be assessed and get a lung scan which could pick up around 290 cancers.
To check eligibility for the programme, visit the SWAG website.