Elizabeth Ngan MD,MSc, Presenter: Nothing to Disclose

Barbara Campbell MD,FRCPC, Abstract Co-Author: Nothing to Disclose

Gavin Low MBChB, MRCS, FRCR, Abstract Co-Author: Nothing to Disclose

To assess the need for spot compression views and the impact on average glandular dose (radiation dose to the breast tissue) with combined Breast Tomosynthesis and Digital Mammography in comparison to Digital Mammography alone.

Since May 2009 at the Cross Cancer Institute in Edmonton, Canada, over 5000 mammograms have been performed using combined Digital Mammography and Digital Breast Tomosynthesis. The patient population consists primarily of patients with a past medical history of breast cancer as well as patients who are presenting for diagnostic work-up of a specific clinical or imaging finding. The average glandular dose, number of tomosynthesis images and number of patients requiring spot compression views were calculated for three groups of consecutive patients: immediately prior to, immediately after and 20 months after the implementation Breast Tomosynthesis (BT). A chi-square test was used to determine the statistical significance of changes in the rate of spot compression views. Preliminary data on 301 patients has been analyzed with plans to review at least 600 patients.

Preliminary data shows an 8.2% relative reduction in the rate at which spot compression views were obtained after implementation of Breast Tomosynthesis, which is not statistically significant. No further reduction in the spot compression rate was observed in the group of patients imaged 20 months after BT implementation in comparison to the group imaged immediately after implementation of BT. However, the average glandular dose more than doubled (mean increase of 4.5 mGy / breast with an average breast thickness of 59 mm) after BT implementation. On average, an additional 128 tomosynthesis images/breast were reviewed.

The rate at which spot compression views were obtained after implementing Breast Tomosynthesis decreased but not by a statistically significant amount.

The implementation of Breast Tomosynthesis in combination with conventional Digital Mammography did not result in a statistically significant decrease in the number of spot compression views obtained.

Ngan, E, Campbell, B, Low, G, The Utilization of Spot Compression Views and Average Glandular Dose in a Combined Digital Breast Tomosynthesis and Digital Mammography Clinical Practice.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11013915.html