A quantitative evaluation of film and film/screen combinations for mammographic examination

A test phantom containing simulated micro-calcifications was constructed. This was imaged by seven systems suitable for use in mammography, firstly in scatter-free conditions and secondly with the addition of tissue-equivalent scattering material. The ability of the systems to resolve micro-particles of known size was assessed using the techniques of signal detection theory. The resultant receiver operating characteristic curves separated the systems into three major groups. Firstly, high resolution systems requiring high radiation dose techniques; secondly at the other extreme, a mediocre imaging system producing its results at low radiation levels; and thirdly a larger middle group producing intermediate resolution of fine particles at similar, acceptable dose levels. The ability to image small particles does not increase linearly with the radiation dose. Scatter did not affect all of the systems to the same extent.