Radiation Lab Simulator

Beam Penetrability Lab

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The fraction of x-ray photons which penetrate an absorber depends upon their energy. The higher the photon energy the fewer photons are absorbed and thus the more photons that penetrate a given absorber.

An x-ray beam contains a spectrum of energies ranging from 0 keV to the X keV where X is the kilovoltage set on the x-ray generator. Any change in the x-ray spectrum will affect the penetratbiltiy of the beam. While kVp affects the beam spectrum and thus benetrability, mA and exposure time do not.

Lab

• Make a pair of exposures at a set x-ray technique (kVp, mA, and exposure time), the first exposure with no absorber in the beam and the second exposure with an absorber between the x-ray tube and dosimeter.and calculate the fraction of beam that penetrates the absorber.
• Make additional exposure pairs changing either kVp, mA, or exposure time. Each exposure of the pair should be done at the same technique, one without and one with an absorber in the beam. Calculate the fraction of beam that penetrates the absorber for each pair.
• Note the change in the fraction penetration as you change each technique factor.

This lab simulation allows you to set up exposure factors, make a simulated exposure, and measure the output. There are two ways you may perform this lab.

1. Free selection of exposure factors
   
   OR
   
   
2. Make series of exposures changing a single parameter (note how output (mR) and normalized output (mR/mAs) varies with that parameter)

kVp	50 60 70 80 90 100 110 120
mA	10 25 50 100 200 300 400
Exposure time (ms)	50 100 200 300 400
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