Deck 9: X-ray Interaction with Matter

Question 1

An outer-shell electron is ejected and the atom is ionized during _____________.

A) photoelectric interactions
B) Compton interactions
C) coherent scattering
D) pair production

Answer 1

Compton interactions

Question 2

Barium is a good contrast agent because of its __________________.

A) low atomic number
B) high atomic number
C) light color
D) low density

Answer 2

high atomic number

Question 3

Only at energies above 10 MeV can _______________ take place.

A) photodisintegration
B) pair production
C) Compton scatter
D) photoelectric absorption

Answer 3

photodisintegration

Question 4

K-shell binding energy increases with increasing ____________.

A) mass density
B) kVp
C) atomic number
D) mAs

Question 5

A negative contrast agent is _________.

A) air
B) iodine
C) barium
D) water

Question 6

The two primary forms of x-ray interaction in the diagnostic range are ________________.

A) Compton scattering and photoelectric absorption
B) Compton scattering and pair production
C) photoelectric absorption and coherent scattering
D) coherent scattering and Thompson scattering

Question 7

Compton scatter is directed at _____ angle from the incident beam.

A) a 180°
B) a 90°
C) a 0°
D) any

Question 8

Which has the greatest mass density?

A) Fat
B) Soft tissue
C) Bone
D) Air

Question 9

Differential absorption is dependent on (the) ________________.

A) kVp of the exposure
B) atomic number of the absorber
C) mass density of the absorber
D) All of the above

Question 10

When the mass density of the absorber is __________, it results in __________ Compton scatter.

A) decreased, increased
B) increased, increased
C) increased, decreased
D) decreased, decreased

Question 11

As kVp ___________, the probability of photoelectric absorption ______________.

A) increases, remains the same
B) increases, decreases
C) decreases, decreases
D) decreases, remains the same

Question 12

Which x-ray interaction involves the ejection of the K-shell electron?

A) Coherent scattering
B) Compton interaction
C) Pair production
D) Photoelectric absorption

Question 13

In ________________, there is complete absorption of the incident x-ray photon.

A) photoelectric interaction
B) Compton interaction
C) pair production
D) coherent scatter

Question 14

The scattered x-ray from a Compton interaction usually retains _____ of the energy of the incident photon.

A) none
B) little
C) most
D) all

Question 15

The use of contrast agents increases the amount of ________________.

A) differential absorption
B) Compton scatter
C) photoelectric absorption
D) All of the above

Question 16

Attenuation is caused by ______________.

A) absorption
B) scattering
C) transmission
D) Both A and B

Question 17

Differential absorption in diagnostic imaging is primarily caused by ____________.

A) photoelectric absorption
B) Compton scatter
C) pair production
D) All of the above

Question 18

Because of differential absorption, about _____% of the incident beam from the x-ray tube contributes to the finished image.

A) 0.5
B) 1.0
C) 50
D) 95

Question 19

An incident x-ray interacts with an atom without ionization during ______________.

A) photoelectric absorption
B) Compton scattering
C) coherent scattering
D) pair production

Question 20

___________ occurs only at the very high energies used in radiation therapy and in nuclear medicine P.E.T. imaging.

A) Coherent scatter
B) Compton scatter
C) Photoelectric absorption
D) Pair production

Question 21

X-rays transmitted without interaction contribute to ___________________.

A) photoelectric absorption
B) the radiographic image
C) the image fog
D) beam attenuation

Question 22

If 5% of an incident beam is transmitted through a body part, then 95% of that beam was ______________.

A) scattered
B) attenuated
C) absorbed
D) back-scattered

Question 23

High kVp techniques reduce ____________.

A) patient dose
B) differential absorption
C) image fog
D) All of the above

Question 24

At energies below 40 keV, the predominant x-ray interaction in soft tissue and bone is ______________.

A) coherent scatter
B) Compton scatter
C) photoelectric absorption
D) photodisintegration

Question 25

Compton interactions, photoelectric absorption, and transmitted x-rays all contribute to _________________.

A) image fog
B) differential absorption
C) patient dose
D) attenuation