Direct radiography trumps computed radiography for cancer detection

Digital direct radiography (DR) is more effective than computed radiography (CR) in detecting breast cancer, according to an online study published May 14 in the journal Radiology. Accordingly, the researchers suggest that women should be informed of the potential for lower cancer detection with CR.

For the study, researchers led by Anna M. Chiarelli, Ph.D., a senior scientist in Prevention and Cancer Control at Cancer Care Ontario in Toronto, relied on data from the Ontario Breast Screening Program. They identified three groups of women ages 50 to 74 screened between Jan. 1, 2008 and Dec. 31, 2009--403,688 women screened by film mammography, 220,520 by DR and 64,210 by CR.

They found that DR detected 4.9 cancers per 1,000 mammograms, which was just slightly better than film mammography's performance (4.8). But, DR significantly outperformed CR's detection rate of 3.4 cancers per 1,000.

"CR was 21 percent less effective than DR. This could result in about 10 fewer cancers detected per 10,000 women screened," Chiarelli said in an announcement. "There may be several technical reasons reported by others for the lower effectiveness of CR, including loss of spatial resolution, or sharpness, and increased image noise, or granularity."

In Ontario there was an immediate response to the study as the provincial government announced it was replacing the province's CR devices.

"I thought it was very important to take action to correct this," Ontario Health Minister Deb Matthews said Monday according an article in The Globe and Mail. She added that the study provides "very clear evidence on what we need to do. We are moving very quickly to replace the mammogram technology that isn't providing as high a quality as it could be."

According to The Globe and Mail, of the 316 mammography machines used for screening in Ontario, 76--or a little less than 25 percent--are CR devices. They will be replaced with DR devices at a cost of $25 million.

To learn more:
- see the study abstract
- read the announcement from the RSNA
- see the article in The Globe and Mail