link to lecture transcript - UT-H GSBS Medical Physics Class Site
link to lecture transcript - UT-H GSBS Medical Physics Class Site
link to lecture transcript - UT-H GSBS Medical Physics Class Site
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This figure is a plot taken from Johns & Cunningham. For each value of incident<br />
pho<strong>to</strong>n energy, we have a different curve for dσ/dE.<br />
Note first, that for each pho<strong>to</strong>n energy, there is a maximum energy of the Comp<strong>to</strong>n<br />
electron. What is this maximum electron energy? Recall that the maximum energy<br />
imparted <strong>to</strong> the Comp<strong>to</strong>n electron occurs when the pho<strong>to</strong>n is scattered 180°, or<br />
backscattered. We determined this quantity in the previous <strong>lecture</strong> <strong>to</strong> be equal <strong>to</strong> the<br />
energy of the incident pho<strong>to</strong>n multiplied by the ratio 2α divided by 1 + 2α. For<br />
example, for a 1 MeV pho<strong>to</strong>n, the energy of the scattered pho<strong>to</strong>n is 204 keV, so the<br />
maximum energy of the Comp<strong>to</strong>n electron is 796 keV. For a 500 keV pho<strong>to</strong>n, we<br />
can calculate the maximum electron energy <strong>to</strong> be a bit less than 350 keV.<br />
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