This work describes the development of a system designed to measure important operational parameters of mammography equipment, as kVp, tube current, exposure time, dose and half-value layer (HVL) in any field location. This system is based on a device with a Si semiconductor sensor, placed under the X-ray tube (over the unit table, for example), which detects the X-ray photons, yielding an electric current proportional to the beam intensity. This signal is driven to a digitizer card coupled to a notebook where a software provides the signal reading and treatment. The kVp measurement is based on the ratio of two signals, one filtered and other non-filtered (reference) from the same sensor. This kind of signal is obtained by detecting the sensor output during the X-ray exposure with a circular shaped aluminum wedge rotating over it. With a single exposure, the software allows to determine the actual parameters by this signal analysis. In addition, HVL in any field location can be determined by a previous developed computer simulation procedure. Calibration curves are stored so that the software compares the actual reading from the sensor X-ray exposures with the stored data to determine how accurate the tube under investigation is working. Development tests with a Trex Medical Contour 2000 unit have shown that the system response is in agreement with calibrated devices used for checking the parameters. An advantage of this system is the possibility of storing a lot of information requested for quality assurance programs.