x ray plate 15 that holds the film cassette not shown as well as serving as a compression surface against which the compression paddle 14 can compress tissue e g a breast to be imaged as depicted in fig2 a typically the x ray plate 15 in certain configurations known as a u201c bucky u201d is stationary and includes an opening 16 into which an x ray cassette 17 is placed prior to imaging the x ray plate has two patient contact surfaces a front face 18 and a functional surface 19 the x ray plate 15 may optionally include radiopaque markers 19 a at the perimeter of the functional surface 19 to allow various marking schemes to be utilized during a procedure fig2 b illustrates a more detailed configuration of compression paddle 14 including a front patient contact surface 20 and a functional patient contact surface 21 paddle 14 is typically constructed of a clear radiolucent plastic material and is designed to be removably attached by an interchange assembly 22 to the movable working arm of the mammography machine not shown these paddles are configured in various geometries as depicted in fig3 a 3c to accommodate various patient anatomies and specific needs of mammographers such as coned compression paddles 3 a spot compression paddles 3 b and the axillary paddle shown as fig3 c all configured to attach to the mammography unit through standard interchange assembly 22 as shown earlier similarly the x ray cassette holder may be adapted by various ancillary modules such as the spot compression fitting 41 shown in fig4 a and a magnification fitting 42 shown in fig4 b the entire compression system compression paddle and x ray plate can further be modified to accommodate a stereotactic biopsy procedure as illustrated in fig5 in.