A method to investigate image blurring due to mammography machine compression paddle movement

Abstract Background Compression paddles can move during mammography exposures. Speculation suggests that this movement can cause image blurring. No research has been published to demonstrate whether such movement could cause image blurring. Aim Develop a method to determine whether paddle movement can cause image blurring Method A Hologic Selenia Dimensions mammography machine calibrated to give compression force in Newtons (N) with 24 × 30 cm fixed and flexible paddles was used. Eleven metal ball-bearings with 1.50 mm diameter were inserted onto the surface of a deformable breast phantom. The ball-bearings were placed at various points, from nipple to chest wall. The phantom was compressed using the foot pedal then hand wound to 80 N and also 150 N respectively to represent low and high compression forces used in clinical mammography. Under these conditions, images were created by exposing the phantom/ball-bearings. Image blurring was determined by measuring the change in ball-bearing diameter (distortion) using computer software. Results Ball-bearing diameters increased, illustrating the effect of compression paddle motion on the images. The change in ball-bearing diameter is the highest around the nipple region for both fixed (1.688 ± 0.013 mm at 80 N, 1.694 ± 0.005 mm at 150 N) and flexible (1.714 ± 0.003 mm at 80 N, 1.661 ± 0.005 mm at 150 N) paddles. Conclusion The increase in ball-bearing diameter suggests that image blurring due to paddle movement can be identified on images of ball-bearings adhered to the surface of a deformable breast phantom. Increase in diameter could be used as an indicator of movement severity.