Francesca Proulx MD, FRCPC, Presenter: Nothing to Disclose

Shambhavi Venkataraman MD, Abstract Co-Author: Nothing to Disclose

Richard Earnest Sharpe MD, MBA, Abstract Co-Author: Nothing to Disclose

Alexander Brook PhD, Abstract Co-Author: Spouse, Research Grant, Guerbet SA

Vandana Mukesh Dialani MD, Abstract Co-Author: Nothing to Disclose

Valerie J. Fein-Zachary MD, Abstract Co-Author: Research Consultant, Siemens AG

Priscilla Jennings Slanetz MD, MPH, Abstract Co-Author: Nothing to Disclose

Tejas S. Mehta MD, MPH, Abstract Co-Author: Nothing to Disclose

To evaluate the effects of compression thickness (thickness), breast tissue density (density), and age on mean glandular dose (MGD) received from screening 3D Digital Breast Tomosynthesis (DBT). 

This IRB approved retrospective study included all screening DBT exams performed at our institution from 1/1/2014 to 1/31/2014. Our DBT protocol included 2D and 3D acquisitions. Patient age, density as determined by interpreting radiologist; compression thickness (mm) and total MGD (TMGD, mGy) for the 2 standard (craniocaudal and mediolateral oblique) views per breast were recorded. TMGD was independently compared to thickness, density, and age using univariate and multivariate regression. Subgroup analysis for low vs high density (fatty and scattered vs heterogeneous and extremely dense) was performed.

There were 200 DBT exams with mean age of 56 ±10.0 years (range 35-78). 110 exams were low density [33 fatty (16.5%), 77 scattered (38.5%)] and 90 were high density [67 heterogeneous (33.5%), 23 extremely dense (11.5%)]. The average TMGD was 14.95 mGy and average thickness was 57.3 mm. When correlated with radiation dose, there was a positive correlation with thickness (r=+0.92), but weak correlation with density (r=+0.20) and age (r=0.21). Thickness is a significant determinant of total radiation dose (R2=0.87) and with density (R2=0.04) and patient age (R2=0.04) to a lesser extent. Using the multivariate model, we found that all three variables were statistically significant and increased the ability to predict patient total radiation dose (R2=0.90). For low density, the average TMGD was 15.3 mGy and average thickness was 61.2 mm. For high density, the average TMGD was 14.23 mGy and average thickness was 52.6 mm. Thickness showed a stronger correlation with radiation dose for patients with less dense than more dense breasts (less: r=+0.97, R2=0.96; more: r=+0.91, R2=0.85; p<0.0001), indicating that TMGD increases more quickly with an increase in thickness for patients with low density breasts than for patients with high density breasts

Radiation dose received by patients undergoing screening DBT significantly correlates with patient’s breast thickness, and less so with breast density and age.

For patients undergoing screening DBT, breast thickness should be considered as an important contributor to overall radiation dose in addition to breast density and patient age.

Proulx, F, Venkataraman, S, Sharpe, R, Brook, A, Dialani, V, Fein-Zachary, V, Slanetz, P, Mehta, T, Radiation Dose during Screening Digital Breast Tomosynthesis: Does Patient Age, Compression Thickness or Breast Tissue Density Matter? .  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14008022.html