Nowadays betatrons are widespread and used in many branches of technics and engineering. They can be applied to build systems of material inspection. Screening systems with betatrons are cheaper than detectors with He-3 and allow quickly inspect wide objects, such as cars. To construct efficient and effective systems betatron must be well configured. Measurements of electronic beam are taken place mostly during injection or after ejection. Deep analysis of measuring methods was made. Calorimetric, acoustic, collector and emission methods can not be applied because of their nontrasparency. Radiation methods are not effective enough because of their low sensibility. Ionization method was considered to be the most efficient. It is transparent and can be applied to measure not only current, but coordinates of electronic beam gravity center. The residual gas is ionized by the circulated electronic beam. The number of appeared secondary electrons grows proportionally with current. Signal electrodes are placed over and under beam direct in vacuum camera, the difference of potential is about 2 kV. Because of the electric field electrons move along the lines of magnetic field to collector and than through resistors go to the ground. Voltage on resistors goes in direct proportion with beam current. The principal idea and scheme of measurement tool is created. Applied to betatrons, it can help increase the efficiency of inspecting complexes.