Method and apparatus for measuring the applied kilovoltage of X-ray sources

摘要

An improved method and apparatus for accurately measuring the applied kilovoltage (KV) of an X-ray source over a wide dynamic operating range. A pair of radiation detectors are mounted beneath a rotatable disc having disposed thereon a plurality of metallic absorbers. To measure applied KV, two exposures are required. In the first exposure, called the "calibration" exposure, the detectors are filtered by two absorbers of equal thickness (t1) and the detected X-ray intensities are measured, processed, and stored in a digital memory. In the second X-ray exposure, referred to the "measure" exposure, the filter wheel is automatically advanced so that one detector is filtered by an absorber of thickness (t1) and the second detector is filtered by an absorber of thickness (t2). The detected X-rays are gain measured and the ratio of the signals calculated to determine the relative penetrating energy. The data from the second measurement is then modified in accordance with the data from the calibration exposure before applied KV is derived to correct for gain differences in the detectors and associated electronics as well as for any nonuniformities in the radiation striking the detectors. Offset errors and drifts in the electronics are also automatically compensated for.