Knowing the kVp and mAs for an x-ray machine, I need to model it as a source in my Monte Carlo input model. I know how to use these inputs to calculate the average energy of the spectrum, but hope someone can help me determine a) how I can calculate the exact spectrum (which parameters would I even use for this?) and b) how to model this in MCNP5?
I have a attached a screenshot of the guide I am using. This function seems ideal but the explanation is too brief for me to understand what inputs it takes.
There is various way to define an X ray spectrum. There is a small program that name is SpecCalc. Mostly, i obtain the spectrum data from this code. Afterwards, i define in SDEF command considering the spectral distribution source.
I have used the Win x-ray for these purposes: http://montecarlomodeling.mcgill.ca/software/winxray/winxray.html
Dear Mr. Erik,
The first thing you have to consider to do this is the geometry (dimensions), the material composition of your target and the energy of your primary electron source. These parameters have a strong influence on resulting photon spectrum. Concerning the Monte Carlo package, I did not work before with MCNP, but view the simplicity of the model (a simple electron source and a basic target) I think it should be easy to implement.
The X-ray spectrum is certainly not Maxwellian.
For (apparently) similar simulations I used the IPEM catalog of X-ray spectra produced in 1979 , which was upgraded in
Catalogue of Diagnostic X-Ray Spectra and Other Data
- Journal of Radiological Protection 18(1)
This reference is on Research Gate (you might request the CD-ROM from the authors).
From the catalog you get the intensity of the spectrum at the various energies, depending on kV, anode composition, anode angle ... . I used it in MCNP to describe the X-ray source as a set of monoenergetic sources, one per 1-keV channel, with the intensity renormalised to get the sum =1 .
Dear Eirk
Actually the KV and mA are the parameters affecting the beam quality of X-rays.
kV affecting the energy of X-rays where the max. energy in keV is the same KVp applied and according to the beam characteristics (narrow or wide beam) you can suggest the resolution of the beam then the spectra is known.
mA affecting the out put dose of x-ray i.e. the number of photons and you may get a factor between the mA and the number of x-ray photons (Intensity if X -rays)
The spectrum will depend on your target geometry, and if you have water cooling in the beam, even on that. The best would be that you first model the incident beam and the target, ensuring correct geometry, and then use the output spectrum of the first model as the input to your photon model.
There is various way to define an X ray spectrum. There is a small program that name is SpecCalc. Mostly, i obtain the spectrum data from this code. Afterwards, i define in SDEF command considering the spectral distribution source.
Also there is an old program, the SRS78, which simulates the source (anode angle, anode material, high voltage riple, inherent filtation) and gives detailed information fot the produced spectrum. As it is mentioned the SDEF card is the appropriate card to input the spectrum into the MCNP
I was able to produce x ray spectrum by using penepma, a Monte Carlo code for simulation of x-ray emission spectra using Penelope. It somehow easy to handel
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