Objective: To evaluate the intermethod agreement in the measurement of compression force as well as variations in the testing of different mammography systems. Materials and Methods: Ten compression force measurements were performed for each proposed method on each mammography apparatus (Mammomat 3000-Siemens, Mammo Diagnostic UC-Philips and Alpha ST-GE), with an evaluation of the differences among the mammographic equipments as far as the application of such measurement methods is concerned, as well as the differences among the applied methods. Results: Significant differences were observed among the results for the different systems and methods, and the values measured with the aid of a bathroom-scale-type dynamometer resulted in compression force underestimation. Each compression system presented different responses for the proposed methods. Conclusion: Differences were observed among compression systems and among proposed methods. Thus the choice of the way the compression test is performed is critical for the acceptance of the mammography equipment, the technical lead being the most competent to define the most appropriate and realistic testing method. It is suggested that the compression force measurement should be performed with an extension dynamometer, rather than with a compression dynamometer, in cases where the mammography compression system functioning is not known.

Keywords: Mammography; Compression force; Quality control.