Abstract: A method of measuring radiation for a radiation measurement device with at least two Geiger-Muller counter tubes of different sensitivity. A high voltage supply is in connection with each of the Geiger-Muller counter tubes and pulse shaping devices are connected to the Geiger-Muller tubes to generate output signals based on the intensity of radiation. A high-speed counter is coupled to the pulse shaping devices A microprocessor includes program storage and random access memory and is capable of switching between the Geiger-Muller tubes based on the radiation intensity. Information generated by the high-speed counter and the microprocessor is visually displayed. At least one Geiger-Muller counter tube generates pulses wherein an actual integration interval is determined by a measurement algorithm. Stable and accurate readings are made at low radiation intensity while providing quick response to significant changes in radiation intensity.