information derived from breast self - examination is recorded using a system that includes a plurality of transparent overlays . each overlay has a plurality of images depicting front and side views of right and left female breasts , with each image having a coordinate system . a writing board has a surface with a number of pegs extending therefrom . when an overlay is placed against the writing board surface the pegs extend through holes in the overlay . the pegs and holes provide a mechanism that registers the images on multiple overlays applied against the surface . an overlay is used to record information about the position and size of masses detected in a breast . each overlay represents the condition of the breast at a different point in time .