A recent study conducted by scientists at Cancer Care Ontario in Toronto, Canada, indicates that direct DR is more effective than CR in breast cancer detection. Both techniques have been used and there was no evidence that one technique should be more favored due to higher effectiveness or accuracy than the other.
DR or digital radiography is an online system that comprises x-ray sensors that allow radiologists or technicians to read images real time as they are produced digitally and automatically shown on computer screens where they can be saved, modified or deleted. CR or computed radiography uses a cassette-based removable detector and an external reading device, which are both used to create and show the image digitally.
DR has been used progressively Cancer Care Ontario since 2006, and only recently has the study shown that direct DR would have better results than CR in detecting breast cancer. Nonetheless, although DR is more widely used than screen-film mammography (SFM), their detection rates are somehow equivalent, but this statement has been proven true only for women aged 50-74.
The study was primarily conducted on the results of tests screening for breast cancer in women ages 50-74. The researchers used data from the Ontario Breast Screening Program and studied the detection rates for women ages 50-74 who were screened with DR, CR and SFM between 2008 and 2009. And the results were compared with those of a 12-month follow-up with SFM results as a reference. The study included a large sample size and comparison of concurrent cohorts, which adds to the validity and reliability of the study results. While some of the shortcomings of this study include nonrandomized design, lack of data on radiologists and the fact that the findings are specific to a certain age group of women, 50-74, and so can’t be generalized to symptomatic women or those of different age groups.
The lead author, Dr. Anna M. Chiarelli, PhD, senior scientist in Prevention and Cancer Control at Cancer Care Ontario, announced the study results in a news release stating that CR was 21% less effective than DR, meaning that 10 fewer cancers would be detected per 10,000 women screened. DR and SFM showed similar cancer detection rates, while CR showed a lower rate than both. As for recall rates, using SFM as a reference, DR rates were higher and CR were lower. Dr. Chiarelli also stated that there may be several technical reasons reported by others behind the lower CR rates which include loss of spatial resolution, or sharpness, and increased image noise, or granularity.
In conclusion, the study shows that although DR and SFM have equivalent effectiveness in detecting breast cancer among women ages 50-74, CR has shown a noticeable decrease in detection rate. Thus, screening programs should monitor the performance of CR separately and report their findings to the medical community. Also, women being screened should be informed of the lower cancer detection rates in order to make an informed decision regarding their screening choice with their physicians.