Design of a Microcontroller Based and X-Ray Waveform Independent kVp-Meter

The kVp setting is one of the major factors affecting the image quality in X-ray imaging and should be annually measured and calibrated if necessary. In this work, a kVp-meter is designed around the ATmega16 (Atmel) microcontroller, based on the physical principle that the linear attenuation coefficient of materials, namely copper has a smooth dependence on the energy level of the X-ray photons. Based on the logarithm of the ratio of the radiation intensities through 0.5mm and 1mm thick copper filters, a look-up table is generated in the range 60-120kVp. Logarithmic operation increased the precision at higher kVp values. Since sampling is performed over the exposure period in a continuous manner, the measurement is not affected by the X-ray waveform. A prototype unit was built and the performance was tested in terms of accuracy, precision and reliability.