A new study has found one kind of mammogram is less effective at detecting breast cancer than others.

The Cancer Care Ontario study found digital direct radiography and screen film mammograms are better than digital computed radiography mammograms or C-R, at pinpointing breast tumours.

C-R technology is used nationally and internationally, and currently accounts for 20 per cent of all mammography machines in Ontario.

The province now says it will phase out all C-R devices.