The calibration and characterization of a research x-ray unit

The proper characterization of an X-ray unit is necessary for the utilization of the source as a dosimetry calibration standard. Upon calibration, the X-ray unit can be used for X-ray calibrations of survey, diagnostic, and reference-class, instruments and for X-ray irradiations of personnel dosimeters. It was the goal of this research to provide the Radiation Calibration Laboratory at Oak Ridge National Laboratory with a characterized research X-ray unit that could be used in reference dosimetry. The energy spectra were characterized by performing half value layer measurements and by performing a spectral analysis. Two spectral reconstruction techniques were investigated and compared. One involved using a previously determined detector response matrix and a backstripping technique. The other reconstruction technique was developed for this research using neural computing. A neural network was designed and trained to reconstruct measured X-ray spectra from data collected with a high- purity germanium spectroscopy system. Five X-ray beams were successfully characterized and found to replicate the ANSI N13.11 and the National Institute of Standards Technology X-ray beam codes. As a result, these prepared X-ray beams have been used for reference dosimetry. It has been shown that a neural network can be used as a spectral reconstruction technique, which contributes less error to the lower energy portion of the spectrum than other techniques