SU‐GG‐I‐132: A Scatter Removal Method for Digital Breast Tomosynthesis

Abstract

Purpose: To develop a scatter removal method for digital breast tomosynthesis based on physical measurements. Method and Materials: A Hologic prototype digital beast tomosynthesis system was used to generate projection images. A CIRS anthropomorphic breast phantom was first imaged at a low mAs with an array of beam stops between the x‐ray source and the breast. For each projection image, local minima, which were near the centers of the beam‐stop shadows, were located using a Matlab program. The pixel values at these local minima were then interpolated and a scatter image was generated. The breast phantom was then imaged again at a higher mAs without the beam‐stop array. The total mAs of two exposures was kept the same as the mAs recommended by Hologic for a breast with the same thickness. The scatter‐free projections were obtained by subtracting the scaled scatter images from the corresponding projections acquired in the second exposure. 3D breast was reconstructed from the scatter‐free projections. Results: For a 6 cm breast, the scatter‐to‐primary ratio could be as high as 0.4 even though there was an air gap between the breast and the detector. The scatter‐free projection images shown higher image contrast. Conclusion: Contrast‐to‐noise ratio may be increased and artifacts due to scatter may be reduced when 3D breast is reconstructed from scatter‐free projections. The overall effect of scatter subtraction on the image quality needs further investigation.