Tesco has been criticised for offering vouchers for health scans through its Clubcard loyalty scheme.
The Society of Radiographers said the promotion for CT scans - which use X-rays to help detect tumours and other illnesses - did not make risks from radiation exposure clear and was "inappropriate" for the retailer.
Society chief executive Richard Evans also said they would prompt "unnecessary anxiety" for people who uncovered apparent abnormalities only to find out they are harmless.
He told the BBC: "I wouldn't want to underplay the sense of relief if something positive and dangerous is found and dealt with in good time.
"However, for every one of those there'll be an untold number who are taking up a GP appointment slot for no real reason, who are suffering unnecessary anxiety."
Tesco said the firm it uses to provide the scan service - Lifescan - employed qualified staff and explained any risks to customers.
Lifescan's medical director, Dr John Giles added that low doses of radiation were involved - with the dosage from a heart, lung and colon scan being equivalent to living in Cornwall for a year.
"There's no evidence of any harmful effect from that kind of exposure, otherwise I suppose we'd have to have health warnings up on the signs driving into Cornwall," he told the broadcaster.
But the Society of Radiographers said more information about the scans needed to be provided at the Clubcard stage.Reuse content