A study recently published in Radiology showing that mammography using digital direct radiography (DR) is more effective at detecting breast cancer than mammography using computed radiography (CR) had an immediate impact on healthcare in the province of Ontario, where the research was conducted.
On May 14, the day after the Radiology study was published online, Deb Matthews, minister of health and long-term care for Ontario, announced that based on the results of the study, the province would be phasing out CR mammography devices and replacing them with DR mammography devices over the coming months. The Radiology study was based on data from the Ontario Breast Screening Program (OBSP).
Researchers are understandably excited about the outcome of their study. “In the OBSP, we strive for excellence and we want to provide women coming to this program with the best technology possible,” said the study’s lead author, Anna M. Chiarelli, Ph.D., senior scientist in Prevention and Cancer Control at Cancer Care Ontario in Toronto. “Until this study was conducted, there was really no clinical evidence suggesting there was this difference. We’re very confident in our data, so the government decided to take these measures in Ontario.”
In the study, Dr. Chiarelli and colleagues identified three groups of women 50 to 74 years of age who were screened in the OBSP betweenJanuary 1, 2008 and December 31, 2009. Slightly more than 400,000 women were screened with screen-film mammography, 220,520 were screened with DR and about 64,210 with CR mammography. All were followed for 12 months after screening.
DR mammography was able to detect 4.9 cancers per 1,000 mammograms (comparable to screen film mammography’s 4.8 cancers per 1,000 mammograms) compared to just 3.4 cancers per 1,000 mammograms detected by CR mammography.
The difference lies with the technical process that computed radiography uses to acquire an image, according to researchers. CR uses a cassette that houses the imaging plate that records the image. That cassette is then placed in a reader to create a digital image. DR technology, on the other hand, produces an image directly.
“With CR mammography, information is lost in processing,” said Derek Muradali, M.D., co-author of the study and head of the Division of Breast Imaging at the University of Toronto. “The images tend to lower resolution compared to DR mammography.” he said.
Despite Ontario’s decision to replace CR mammography with DR mammography, Drs. Chiarelli and Muradali said that women who underwent CR mammography still have a very small chance of having developed an undetected cancer.
“The 21 percent difference in the cancer detection rate would amount to about 10 fewer cancers detected for every 10,000 women screened,” Dr. Chiarelli said. “We feel that’s probably a pretty small number, as long as women continue to get their regular screening with the newer technology.” q
The Refresher Course, “Current Issues in Breast Cancer Screening,” will be held from 2 to 3:30 p.m., Sunday, Dec. 1, at RSNA 2013. Registration for this and other sessions is underway at RSNA.org/Annual_Meeting.aspx.
Access the Radiology study, “Digital Compared with Screen-Film Mammography: Performance Measures in Concurrent Cohorts within an Organized Breast Screening Program,” at Radiology.rsna.org/content/early/2013/04/29/radiol.13122567.
The newest volume of Radiology Select, Volume 4: Breast Cancer Screening, is now available to RSNA members and non-members for purchase.
The fourth in the continuing series of selected Radiology articles focusing on a specific subspecialty topic, Radiology Select, Volume 4, features 34 articles that cover:
The edition is available in print, online and tablet formats.
The online self-assessment module (SAM) edition includes five SAM tests with an opportunity to earn 15 SAM credits and 15 CME credits. This material can be applied towards the American Board of Radiology (ABR) self-assessment requirement.To purchase and for information on Radiology Select, visit RSNA.org/RadiologySelect.
Click to view a video introduction by Radiology Select Editor Deborah Levine, M.D.
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