Method and apparatus for the measurement of x-ray sources

Abstract

An X-ray measurement device (20) is disclosed which utilizes a pair of detector units (29, 30) which receive X-rays through filters (40, 41) of differing attenuation of X-rays. The detector units preferably include two pairs of photodiode detectors arranged symmetrically in four quadrants with the diodes in each detector unit in diagonally opposite quadrants, thereby minimizing the effects of changes in orientation of the device with respect to the axis of the X-ray beam. The outputs of the detector units are passed to variable gain amplifiers (42, 43) the gains of which are automatically adjusted to bring the output voltages within a desired range, and the outputs of the amplifiers are integrated by integrators (49, 50). After a selected period of time, the integration is stopped and the output voltages of the integrators (49, 50) are held and passed to an analog-to-digital converter (57) which determines the ratio of the output signals from the integrators and provides a multi-bit output signal on a bus (58) to the address lines (59) of a preprogrammed memory (60). The data location addressed by the output signal from the conventer may contain data which corresponds to the kVp value of an X-ray machine at the calculated ratio, and the output data from the memory is provided to a display unit (63) to provide a visual display in decimal form of the measured kVp value.