link to lecture transcript - UT-H GSBS Medical Physics Class Site

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We find that dE/dθ is the incident photon energy, hν, times α sin θ, divided by the quantity [1 + α(1 – cos θ)] 2 . We combine this quantity with dσ/dθ to obtain an expression for dσ/dE, the distribution of energies of Compton electrons. 22
This figure is a plot taken from Johns & Cunningham. For each value of incident photon energy, we have a different curve for dσ/dE. Note first, that for each photon energy, there is a maximum energy of the Compton electron. What is this maximum electron energy? Recall that the maximum energy imparted to the Compton electron occurs when the photon is scattered 180°, or backscattered. We determined this quantity in the previous lecture to be equal to the energy of the incident photon multiplied by the ratio 2α divided by 1 + 2α. For example, for a 1 MeV photon, the energy of the scattered photon is 204 keV, so the maximum energy of the Compton electron is 796 keV. For a 500 keV photon, we can calculate the maximum electron energy to be a bit less than 350 keV. 23
Page 1 and 2: Today, we continue our talk about C
Page 3 and 4: We previously derived an equation f
Page 5 and 6: So σ 0 is the classical cross sect
Page 7 and 8: Let’s look at this graph. Notice
Page 9 and 10: What about the dependence of the Co
Page 11 and 12: The energy transferred to the elect
Page 13 and 14: If we plot the energy transfer coef
Page 15 and 16: The energy transfer coefficient has
Page 17 and 18: What about the scatter coefficient?
Page 19 and 20: Using this equation we can now plot
Page 21: This probability is represented by
Page 25 and 26: We can always calculate what the ma
Page 27 and 28: Remember dσ/dE is relatively const
Page 29 and 30: Now we also look at the graph and s
Page 31 and 32: First, let’s recall that the atte
Page 33 and 34: What we now want to find out is how
Page 35 and 36: So far, our approximations have bee
Page 37 and 38: These values were tabulated by Hubb
Page 39 and 40: So what is the effect of binding en
Page 41 and 42: At higher energies there is no diff
Page 43 and 44: Note that this graph is for very lo
Page 45: The fraction of energy transferred

link to lecture transcript - UT-H GSBS Medical Physics Class Site

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