Absolute kVp calibration using characteristic x-ray yields.

A spectrometer with a high-resolution room-temperature silicon detector was used to obtain spectra including characteristic x-ray peaks produced after fluoroscopic beams were incident on W, Pb, and Th absorbers. Characteristic x-ray yield points were obtained from spectra taken at several generator kVp settings which produced x rays with energy above the K-shell absorption edge for each element. A line drawn through the yield points when projected to zero yield served to locate the console setting corresponding to the actual K-absorption edge energy for each absorber. The technique is useful for precision measurement of generator kVp and absolute calibration of indirect kVp measuring devices under operational conditions.