X-ray:characterisation of a spectra

[Elena_v]

Hello,
I've simulated the output of a x-ray tube using a software (spekcalc). In my simulation the energy range is 17-170 keV, the air thickness is 1m and there is 1.5 mm of Al. The mA value is 1 (default value).
After the estimation I obtained a characteristic spectra: in y there is the numper of photons [keV cm^2 mAs^-1 @ 1 meter] while in x there are the energy range (17-170 keV). The mean energy = 61 keV, bremsstrahlung = 273 μGy/mAs @1 meter and characteristic energy = 26 μGy/mAs @1 meter.

I know how to estimate the mean energy using the spectra data, but I don't know how the bremsst and the characteristic energy is estimated. Any help?

Moreover, I'd like to know the values at 1.5m of air, so I wanted to use the inverse square law(I1/I2=D1^2/D2^2, where I1 and I2 are the intensity values at D1 and D2 respectively)..can I apply this to bremmst and characteristic energy?

Thanks!

 

[Valerie Park]

The estimation of the bremsstrahlung and characteristic energy values are based on the data that you have obtained from the simulation. You can use the mean energy value to estimate the bremsstrahlung and characteristic energy values. The formula for estimating the bremsstrahlung is:Bremsstrahlung = (mean energy x numper of photons [keV cm^2 mAs^-1 @ 1 meter]) / 1000 The formula for estimating the characteristic energy is: Characteristic energy = (mean energy x numper of photons [keV cm^2 mAs^-1 @ 1 meter]) / 10000 To calculate the values at 1.5m of air, you can use the inverse square law. The formula for this will be:I1/I2 = (D1/D2)^2Where I1 and I2 are the intensity values at D1 and D2 respectively. So, you can use this formula to calculate the bremsstrahlung and characteristic energy values at 1.5m of air.