The report discovered that up to 63% of 111 English hospital trusts have at least one scanner that is a decade old, the point where the technology ideally should be scrapped and replaced with upgraded machines.
The survey found that in one trust, the MRI scanner was 23 years old.
“It's scandalous, frankly. It's a major problem," Dr Giles Maskell, president of the Royal College of Radiologists, told Sky News.
The report by, published in late 2015, called for the NHS to draw up a plan for replacing radiotherapy scanners and technology when they reach their 10-year lifespan date.
“Patients who are being treated on older linear accelerators are not getting the precision of treatment that they would otherwise," said Dr Maskill.
“The effect is there is more radiation to normal tissue around the tumour and not precisely to the tumour itself. It becomes critical if the tumour is near vital organs."
A spokesperson for NHS England responded: “We are working with others across the health system to take this forward as quickly as possible. A range of options for the funding of the linear accelerator replacement programme are being considered.
“These options include the outright purchasing of new equipment, and looking at the potential benefits of leasing. The relevant hospitals will be able to replace and upgrade their equipment in the most cost effective way."