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- Bujila, Robert, et al.
(author)
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A validation of SpekPy: A software toolkit for modelling X-ray tube spectra
- 2020
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In: Physica medica (Testo stampato). - : Elsevier BV. - 1120-1797 .- 1724-191X. ; 75, s. 44-54
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Journal article (peer-reviewed)abstract
- Purpose: To validate the SpekPy software toolkit that has been developed to estimate the spectra emitted fromtungsten anode X-ray tubes. The model underlying the toolkit introduces improvements upon a well-knownsemi-empirical model of X-ray emission.Materials and methods: Using the same theoretical framework as the widely-used SpekCalc software, new electronpenetration data was simulated using the Monte Carlo (MC) method, alternative bremsstrahlung crosssectionswere applied, L-line characteristic emissions were included, and improvements to numerical methodsimplemented. The SpekPy toolkit was developed with the Python programming language. The toolkit was validatedagainst other popular X-ray spectrum models (50 to 120 kVp), X-ray spectra estimated with MC (30 to150 kVp) as well as reference half value layers (HVL) associated with numerous radiation qualities from standardlaboratories (20 to 300 kVp).Results: The toolkit can be used to estimate X-ray spectra that agree with other popular X-ray spectrum modelsfor typical configurations in diagnostic radiology as well as with MC spectra over a wider range of conditions.The improvements over SpekCalc are most evident at lower incident electron energies for lightly and moderatelyfiltered radiation qualities. Using the toolkit, estimations of the HVL over a large range of standard radiationqualities closely match reference values.Conclusions: A toolkit to estimate X-ray spectra has been developed and extensively validated for central-axisspectra. This toolkit can provide those working in Medical Physics and beyond with a powerful and user-friendlyway of estimating spectra from X-ray tubes.
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- Bujila, R., et al.
(author)
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Characterization of Beam Shaping Filters and Photon Spectra From HVL Profiles in CT
- 2016
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Conference paper (other academic/artistic)abstract
- Purpose: Advanced dosimetry in CT (e.g., the Monte Carlo method) requires an accurate characterization of the shaped filter and radiation quality used during a scan. The purpose of this work was to develop a method where half value layer (HVL) profiles along shaped filters could be made. From the HVL profiles, the beam shaping properties and effective photon spectrum for a particular scan can be inferred.Methods: A measurement rig was developed to allow determinations of the HVL under a scatter-free narrow-beam geometry and constant focal spot to ionization chamber distance, for different fan angles. For each fan angle, the HVL is obtained by fitting the transmission of radiation through different thicknesses of an Al absorber (type 1100) using an appropriate model. The effective Al thickness of shaped filters and effective photon spectra are estimated using a model of photon emission from a Tungsten anode. This method is used to obtain the effective photon spectra and effective Al thickness of shaped filters for a CT scanner recently introduced to the market.Results: This study resulted in a set of effective photon spectra (central ray) for each kVp along with effective Al thicknesses of the different shaped filters. The effective photon spectra and effective Al thicknesses of shaped filters were used to obtain numerically approximated HVL profiles and compared to measured HVL profiles (mean absolute percentage error = 0.02). The central axis HVL found in the vendor’s technical documentation were compared to approximated HVL values (mean absolute percentage error = 0.03).Conclusion: This work has resulted in a unique method of measuring HVL profiles along shaped filters in CT. Further, the effective photon spectra and the effective Al thicknesses of shaped filters that were obtained can be incorporated into Monte Carlo simulations.
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- Enberg, Rikard, et al.
(author)
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Diffractive vector mesons at large momentum transfer from the BFKL equation
- 2002
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Conference paper (peer-reviewed)abstract
- Diffractive vector meson photoproduction accompanied by proton dissociation is studied for large momentum transfer. The process is described by the non-forward BFKL equation, for which an analytical solution is found for all conformal spins, giving the scattering amplitude. Results are compared to HERA data on \rho production.
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- Esposito, M, et al.
(author)
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PRaVDA: The first solid-state system for proton computed tomography
- 2018
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In: Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB). - : Elsevier BV. - 1724-191X. ; 55, s. 149-154
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Journal article (other academic/artistic)
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