Extra patient movement during mammographic imaging :
an experimental study

Ma, WK; Brettle, D; Howard, D; Kelly, J; Millington, S; Hogg, P

Abstract

Objectives: To determine if movement external to the patient occurring during mammography may be a source of image blur. Methods: Four mammography machines with seven flexible and nine fixed paddles were evaluated. In the first stage, movement at the paddle was measured mechanically using two calibrated linear potentiometers. A deformable breast phantom was used to mimic a female breast. For each paddle, the movement in millimeters and change in compression force in Newton was recorded at 0.5 and 1 second intervals respectively for 40 seconds with the phantom in an initially compressed state under a load of 80N. In the second stage, clinical audit on 28 females was conducted on one mammography machine with the 18x24cm and 24x29cm flexible paddles. Results: Movement at the paddle followed an exponential decay with a settling period of approximately 40 seconds. The compression force readings for both fixed and flexible paddles decreased exponentially with time while fixed paddles have a larger drop in compression force than flexible paddles. There is a linear relationship between movement at the paddle and change in compression force. Conclusions: Movement measured at the paddle during an exposure can be represented by a second order system. The amount of extra-patient movement during the actual exposure can be estimated using the linear relationship between movement at the paddle and the change in compression force. Advances in knowledge: This research provides a possible explanation to mammography image blurring caused by extra patient movement and proposes a theoretical model to analyze the movement.

Citation

an experimental study. British Journal of Radiology, 87(1044), https://doi.org/10.1259/bjr.20140241

• Journal Article Type: Article
• Acceptance Date: Oct 24, 2014
• Online Publication Date: Nov 14, 2014
• Publication Date: Nov 14, 2014
• Deposit Date: Nov 7, 2014
• Publicly Available Date: Apr 5, 2016
• Journal: British Journal of Radiology
• Print ISSN: 0007-1285
• Electronic ISSN: 1748-880X
• Publisher: British Institute of Radiology
• Peer Reviewed: Peer Reviewed
• Volume: 87
• Issue: 1044
• DOI: https://doi.org/10.1259/bjr.20140241
• Publisher URL: http://dx.doi.org/10.1259/bjr.20140241
• Related Public URLs: http://www.birpublications.org/toc/bjr/current