Screen-film systems are used in mammography even now. Therefore, it is important to measure their physical
properties such as modulation transfer function (MTF) or noise power spectrum (NPS). The MTF and NPS of
screen-film systems are mostly measured by using a microdensitometer. However, since microdensitometers are not
commonly used in general hospitals, it is difficult to carry out these measurements regularly. In the past, Ichikawa et al.
have measured and evaluated the physical properties of medical liquid crystal displays by using a high-performance
digital camera. By this method, the physical properties of screen-film systems can be measured easily without using a
microdensitometer. Therefore, we have proposed a simple method for measuring the MTF and NPS of screen-film
systems by using a high-performance digital camera. The proposed method is based on the edge method (for evaluating
MTF) and the one-dimensional fast Fourier transform (FFT) method (for evaluating NPS), respectively. As a result, the
MTF and NPS evaluated by using the high-performance digital camera approximately corresponded with those evaluated
by using a microdensitometer. It is possible to substitute the calculation of MTF and NPS by using a high-performance
digital camera for that by using a microdensitometer. Further, this method also simplifies the evaluation of the physical
properties of screen-film systems.