Question

Which of the following are correct with regard to attenuation of X-ray photons? 

a. The Compton effect refers to the interaction of X-ray photons with free electrons 

b. Attenuation is the difference between the incident beam and the attenuated beam 

c. Photoelectric absorption refers to the interaction of X-ray photons with loosely bound electrons 

d. An increase in atomic number increases the linear attenuation coefficient (LAC) 

e. Elastic scatter results in no loss of energy

Answer 1

a. True. The Compton effect is the interaction of X-ray photons with loosely bound or free electrons. 

b. True.

c. False. Photoelectric absorption is the interaction of X-ray photons with an inner shell or ‘bound’ electron. 

d. True. An increase in atomic number results in a higher probability that a photon will interact with an electron (photoelectric effect) as it passes through the material. 

e. True. This also known as coherent scatter and occurs when the photon does not have enough energy to overcome the binding energy of an electron shell and hence ‘bounces’ off without the loss of energy.