Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2021 Jul;48(7):3630-3637.
doi: 10.1002/mp.14945. Epub 2021 Jun 10.

Technical Note: SpekPy v2.0-a software toolkit for modeling x-ray tube spectra

Gavin Poludniowski  1   2 , Artur Omar  1   3 , Robert Bujila  1   4 , Pedro Andreo  1   3
Affiliations

Technical Note: SpekPy v2.0-a software toolkit for modeling x-ray tube spectra

Gavin Poludniowski et al. Med Phys. 2021 Jul.

Abstract

Purpose: SpekPy is a free toolkit for modeling x-ray tube spectra with the Python programming language. In this article, the advances in version 2.0 (v2) of the software are described, including additional target materials and more accurate modeling of the heel effect. Use of the toolkit is also demonstrated.

Methods: The predictions of SpekPy are illustrated in comparison to experimentally determined spectra: three radiation quality reference (RQR) series tungsten spectra and one mammography spectrum with a molybdenum target. The capability of the software to correctly model changes in tube output with tube potential is also assessed, using the example of a GE RevolutionTM CT scanner (GE Healthcare, Waukesha, WI, USA) and specifications in the system's Technical Reference Manual. Furthermore, we note that there are several physics models available in SpekPy. These are compared on and off the central axis, to illustrate the differences.

Results: SpekPy agrees closely with the experimental spectra over a wide range of tube potentials, both visually and in terms of first and second half-value layers (HVLs) (within 2% here). The CT scanner spectrum output (normalized to 120 kV tube potential) agreed within 4% over the range of 70 to 140 kV. The default physics model (casim) is adequate in most situations. The advanced option (kqp) should be used if high accuracy is desired for modeling the anode heel effect, as it fully includes the effects of bremsstrahlung anisotropy.

Conclusions: SpekPy v2 can reliably predict on- and off-axis spectra for tungsten and molybdenum targets. SpekPy's open-source MIT license allows users the freedom to incorporate this powerful toolkit into their own projects.

Keywords: X-ray imaging; X-ray spectra; X-ray tube modeling; software.

PubMed Disclaimer

References

REFERENCES

    1. Kramers HA. On the theory of x-ray absorption and of the continuous x-ray spectrum. Philos Mag. 1923;46:836-871.
    1. Cranley K, Gilmore BJ, Fogarty GWA, Deponds L. Catalogue of diagnostic x-ray spectra and other data. IPEM Report No. 78. York, UK: IPEM; 1997.
    1. Poludniowski G, Landry G, DeBlois F, Evans PM, Verhaegen F. SpekCalc: a program to calculate photon spectra from tungsten anode x-ray tubes. Phys Med Biol. 2009;54:N433-N438.
    1. Hernandez AM, Boone JM. Tungsten anode spectral model using interpolating cubic splines: unfiltered x-ray spectra from 20 kV to 640 kV. Med Phys. 2014;41:042101.
    1. Punnoose J, Xu J, Sisniega A, Zbijewski W, Siewerdsen JH. Technical Note: spektr 3.0-A computational tool for x-ray spectrum modeling and analysis. Med Phys. 2016;43:4711.