Ch.12

Question 1

The total subject contrast created between two tissues within the patient is dependent upon the differential absorption resulting from:
a. all interactions combined
b. Compton interactions only
c. photoelectric interactions only
d. Thompson interactions only
e. Rayleigh interactions only

Answer 1

a. all interactions combined

Question 2

Of the following, the most likely initial interaction of diagnostic-energy x-rays in high Z-number materials such as bone and contrast agents is:
a. photoelectric interaction
b. Compton interaction
c. characteristic interaction
d. Thompson interaction
e. bremsstrahlung

Answer 2

a.photoelectric interaction

Question 3

A photon with much more energy than the binding energy of the tissue through which it passes will most likely interact by:
a. the photoelectric effect
b. unmodified scattering
c. Compton scattering
d. the characteristic interaction
e. bremsstrahlung

Answer 3

c.Compton scattering

Question 4

Which type of interaction is responsible for making a radiographic image possible?
a. Compton
b. Rayleigh
c. photoelectric
d. unmodified scattering
e. characteristic

Answer 4

c. photoelectric

Question 5

Lead is commonly used as shielding against x-rays because of its very high atomic number. This high Z number makes it most likely that x-rays passing through lead will interact by:
a. photoelectric interaction
b. Compton interaction
c. bremsstrahlung interaction
d. characteristic interaction
e. Thompson interaction

Answer 5

a. photoelectric interaction

Question 6

Gaseous contrast agents, such as air, work to produce high contrast primarily because of their:
a. viscosity
b. density
c. volume
d. atomic mass
e. atomic number

Answer 6

b. density
(low)

Question 7

To increase the proportion of photoelectric interactions (compared to Compton) occurring within the patient, one should:
a. increase mAs
b. decrease mAs
c. increase kVp
d. introduce barium into the anatomy
e. increase field size

Answer 7

d. introduce barium into the anatomy

Question 8

he intensity of the entire x-ray beam is doubled, such that twice as many photons pass into the patient. The ratio between the number of photoelectric interactions and the number of Compton interactions taking place will:
a. double
b. increase
c. decrease
d. remain equal
e. be cut to ½

Answer 8

d. remain equal

Question 9

Which of the following is not a reason why higher kVp levels result in reduced image contrast:

a. photoelectric interactions are lost

b. scattered photons have higher penetrating power

c. a higher percentage of scattered photons are directed forward toward the image receptor

d. Compton interactions increase in number

Answer 9

d. Compton interactions increase in number

Question 10

The reduction in the original number and energy of x-ray photons as they interact with atoms within the patient is called:
a. absorption
b. diffusion
c. attenuation
d. scattering
e. filtration

Answer 10

c. attenuation

Question 11

Which of the following is least effective in producing subject contrast?
a. tissue density
b. tissue thickness
c. tissue atomic number
d. these all have an equal effect

Answer 11

d. these all have an equal effect

Question 12

Subject contrast within the remnant beam of x-rays is directly proportional to:
a. the Compton/photoelectric ratio
b. the photoelectric/Compton ratio
c. the Thompson/Compton ratio
d. the penetration ratio

Answer 12

b. the photoelectric/Compton ratio

Question 13

Bone shows up with high contrast on a radiograph primarily because of its:
a. thickness
b. density
c. atomic number
d. hardness
e. viscosity

Answer 13

c. atomic number

Question 14

Which of the following is directly proportional to the number of interactions taking place within a particular tissue in the patient?
a. atomic number of the tissue
b. thickness of the part
c. density of the tissue
d. fat content of the tissue

Answer 14

c. density of the tissue