Cancer patients could be taught to hold their breath for six minutes to boost the success of radiotherapy, scientists claim.
Keeping the chest and abdomen still helps radiation beams be more precisely delivered to tumours, while avoiding healthy surrounding tissue.
However, every breath can cause this area of the body to move by up to 1.5inches (4cm), limiting the accuracy of the treatment.
University of Birmingham scientists gave 30 volunteers oxygen-enriched air, while removing carbon dioxide from their lungs via a mechanical ventilator.
This made it safe for them to hold their breath for up to six minutes at a time, which they practiced over several days under the supervision of the experts.
The innovative technique may allow cancer patients to stay as still as possible during radiotherapy, the researchers said. But critics say it is 'unlikely to provide any additional benefit'.
Scientists have developed a technique that could enable cancer patients to hold their breath during radiotherapy. This may enable beams to be delivered more precisely to tumours (stock)
It is already being trialed at hospitals in Newcastle, Belgium and the Netherlands.
'Radiotherapy is still a key treatment for tackling cancer,' said study author Dr Mike Parkes.
'But success depends at least in part on patients being able to remain as still as possible while the treatment is ongoing.
'This is a particular challenge for patients being treated for cancers in the chest and abdomen.
'These regions can move up to 4cm each time a breath is taken, limiting the accuracy of the radiotherapy.'
Radiotherapy is often a go-to cancer treatment. It usually involves a series of beams being directed to a tumour at different angles.
'Short breath holds' are already used during the treatment, the scientists wrote in the journal Radiotherapy and Oncology.
The team set out to investigate the 'feasibility and safety of multiple prolonged breath-holds in a single session'.
Safety concerns included a rise in blood pressure, as well as patients simply finding it too difficult.
In the study, 30 volunteers, aged 20-to-25, breathed in 60 per cent oxygen to boost the level of the gas in their lungs. The air we breathe is around 21 per cent oxygen.
Their blood carbon dioxide was removed via a mechanical ventilator, worn as a face mask.
This enabled them to hold their breath safely for much longer than normal, the researchers claim.
In learning to hold their breath, the volunteers were taught how best to inflate and deflate their chest.
When we hold our breath, our diaphragm contracts. This is thought to cause the accumulation of substances that stimulate receptors to 'tell' the brain to breathe, the researchers wrote.
Radiotherapy is a cancer treatment in which radiation is used to destroy tumour cells.
It is most commonly delivered as beams of radiation which are targeted at a tumour and are so powerful that the energy destroys the flesh