The determination of the x-ray beam quality from a continuous (90 - 200 kV) high voltage generator using a pn junction

The ionisation measured in the depletion zone of a pn junction is a function of two parameters usually accepted as defining x-ray quality: the HT applied to the tube and the additional filtration. Inserting screens of different atomic number between the tube and the junction permits the relationships between the flux of secondary electrons and the beam characteristics to be studied. A double nomogram has been constructed to give, without ambiguity, x-ray quality (for continuous voltage generators) for applied voltages from 90 to 200 keV and for filters of 0-6 mm of aluminium and 0-3 mm of copper. (author)