Semi-analytic off-axis X-ray source model. (23rd October 2017)

• Record Type: Journal Article
• Authors: Shamshad, M.; Anjomrouz, M.; Smithies, D.J.; Largeau, A.; Lu, G.; Atharifard, A.; Broeke, L. Vanden; Aamir, R.; Panta, R.K.; Walsh, M.F.; Goulter, B.P.; Healy, J.L.; Bheesette, S.; Bell, S.T.; Bateman, C.J.; Butler, A.P.H.; Butler, P.H.
• Is Part Of: Journal of instrumentation. Volume 12:Number 10(2017:Oct.)
• Page Start: P10013
• Page End: P10013
• Publication Date: 2017-10-23
• Subjects: Scientific apparatus and instruments -- Periodicals; 502.84
• DOI: 10.1088/1748-0221/12/10/P10013
• Languages: English
• ISSNs: 1748-0221

Abstract

Abstract: Spectral computed tomography (CT) systems are employed with energy-resolving photon counting detectors. Incorporation of a spectrally accurate x-ray beam model in image reconstruction helps to improve material identification and quantification by these systems. Using an inaccurate x-ray model in spectral reconstruction can lead to severe image artifacts, one of the extreme cases of this is the well-known beam-hardening artifacts. An often overlooked spectral feature of x-ray beams in spectral reconstruction models is the angular dependence of the spectrum with reference to the central beam axis. To address these factors, we have developed a parameterized semi-analytical x-ray source model in the diagnostic imaging range (30-120 kVp) by applying regression techniques to data obtained from Monte Carlo simulations (EGSnrc). This x-ray beam model is generalized to describe the off-axis spectral information within\pm17^o ±17 o along\theta θ (vertical direction), \pm5^o ±5 o along\phi ϕ (horizontal direction) of the central axis, and can be parameterized for specific x-ray tube models. Comparisons of our model with those generated by SpekCalc, TOPAS, and IPEM78 at central axis show good agreement (within 2% % ). We have evaluated the model with experimental data collected with a small animal spectral scanner.