Implementation of MTSVD method for X-ray spectrum unfolding from compton spectrometry in diagnostic radiology range using MCNPX Monte Carlo code

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Abstract

Determination of X-ray spectrum at various nuclear radiology centers is important in terms of device quality control. Due to the pile-up effect and dead time, this won't be possible by simple methods, and by placing the detector in front of the X-ray beams. Therefore, to obtain the X-ray spectrum, one can use indirect methods like spectroscopy Compton photons scattered at 90° angle. The primary spectrum is related to the Compton spectrum matrix by the response matrix in an equation system. As the coefficients matrix of this equation is ill-conditioned, MTSVD regularization mathematical method was used in this study for spectrum unfolding the X-ray spectra. Finally, the accuracy of the spectrometry was obtained by comparing the unfolded spectra with the IPEM78 theory spectrum. To compare the closeness of the unfolded spectra with the theory, the root-mean-square deviation was obtained, and the percentage error was used for comparison of the half value layer. According to the results obtained in this study, the indirect Compton method can unfold the X-ray spectrum by a good accuracy, i.e., less than 5%, and the relative error for obtaining the HVL, was found to be 2%.

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Journal of Radiation Safety and Measurement
Volume 9, Issue 6 - Serial Number 35
December 2020
Pages 19-26

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